Vincent Herbreteau

Christophe Revillion

Etienne Trimaille

1 QGIS for health applications Chapter 7

GeoHealth and QuickOSM, two QGIS plugins for health applications

Background of the use of GIS for health and the development of dedicated plugins in QGIS

Maps and spatial analyses are increasingly used in the field of health to illustrate the spatial and temporal organization of data and to provide a geographical perspective on health data. Geographic Information Systems (GIS), and geomatics tools in general, are thus used by health organizations (local or international) to inform on the distribution of diseases, by managers to monitor and control epidemics, and by doctors and researchers to understand disease distributions. Scientific publications in the field of health also show the widespread use of spatial maps and analyses. Major organizations such as the World Health Organization, ministries of health in many countries, and research organizations have set up GIS laboratories with geomaticians or health geographers to conduct these tasks. However, many organizations do not have in-house expertise and still wish to conduct such analyses. More and more people in the field of health are thus being trained in geomatics, but implementation remains difficult due to the complexity of the tools and the often sporadic use.

The goal of the GeoHealth plugin, developed for QGIS software, is therefore to provide a simple and intuitive interface so that non-specialist users (i.e. nongeomaticians) who rarely use GIS softwares can meet the main need to map disease cases. In addition, difficulties in accessing spatial data also limit their use. This concerns the identification of relevant data, access rights, their import and potential pre-processing. A solution is proposed here through the use of OpenStreetMap (OSM), a worldwide free and participatory geographic database. OSM is directly accessible from QGIS through the QuickOSM plugin, which allows simple and specific object queries (for example, download vector files of roads, houses or the location of pharmacies in a given area, but as this data exist in OSM). By using the addresses contained in OSM, institutions can geolocate patients and place them on a map. Spatial analyses can also be carried out to assess the impact of landscape features on disease occurrence.

One of the main criticisms of using OpenStreetMap data is its representativeness. As this database is built by participatory contributions, the data are indeed heterogeneous. In turn, an advantage of OSM is that it can be used as a mapping tool to record data to meet a specific need. Thus, in an area without reference data, it is entirely possible to map by photo-interpretation of satellite images or to integrate field data, which will then be imported via QuickOSM.

Finally, the issue of data confidentiality must be addressed, as it is fundamental to the use of data from a health care system. In order to respect anonymity, health data are often aggregated by administrative unit, leading to a loss of knowledge of the local spatial organization of the data. The GeoHealth plugin then proposes a method of approximating point locations, known as blurring ("Blur" function in the extension), with a user-defined accuracy (for example, the indication of locations to within 1 km). To anonymize the location of the patient's place of residence, a quality control of the blurring can be carried out in the plugin, by counting the number of houses in the blurred areas. This method can be easily applied to point epidemiological data in order to preserve the ability of detecting clusters and analyzing the surrounding environment.

Methodology applied

The first need, in terms of mapping applied to health issues, is the production of distribution maps of disease cases. These cases are usually represented by a rate: the ratio of the number of cases to the population on a given administrative scale (country, district, village, etc.). In epidemiology, we refer to the incidence of a disease (or morbidity rate) as the number of new cases of disease that occur over a given period of time in a given population. We also refer to the prevalence of a disease as the number of cases among a population at a given time or over a given period of time (cases that could have been diagnosed before that time) [PIC 01]. A variation of the representation of these incidence maps could be a density map where the number of cases is represented in relation to the surface area of each spatial unit.

The GeoHealth plugin was originally designed to provide an intuitive interface for importing an epidemiological data table and map its incidence, prevalence or density. It allows importing data in various formats and then defining the parameters of the calculation of incidence and symbology in a single window. The plugin also proposes a novel method for anonymizing the location of data (blurring as defined above). The interface has three main tabs: Import, Analysis and Export (figure 7.1), and, for each function, a side menu to guide the user through a sequential process.

Importing data

The data to be mapped is usually in the form of a table. A common example is a table from a registry of patients who have been diagnosed with a disease in a year as recorded by health facilities (hospitals, clinics, etc.) and then synthesized by health managers (ministries of health, health agencies for disease surveillance and control). It can also be a table resulting from health surveys within the framework of active surveillance (research for a disease in a population, search for pathogens in an animal population, search for infectious agents or pollutants in the environment).

Although importing tables is easy in QGIS, occasional users may have difficulties to find the right function. Thus, it is difficult to remember that you can import an Excel file (.xls format) via the "Add a vector layer" button. The interface therefore directly proposes different types of files that can be imported: Shapefile, Raster, Table XLS/DBF, Table CSV, XY to map. This last function (XY to map) corresponds to the QGIS dialog box "Add a delimited text layer" which allows to map a table in csv format that includes latitudes and longitude columns.

QGIS features:

-Data import: Plugins > GeoHealth > Import.

Case geolocation

Geolocation is a crucial step that aims to locate epidemiological data on a map by giving them a spatial reference. There are three possible cases:

-the data table contains for each case the reference (name or identifier of the administrative unit. It can then be associated with a vector layer of the corresponding administrative units; -the data table contains geographic coordinates (latitude and longitude). It is then possible to import the table via the button "XY to map" and indicate the corresponding columns and the projection; -the data table contains postal addresses for each row. These addresses must then be geocoded using national or international address databases (for instance, using Google web services or Nominatim, a search engine for OpenStreetMap data: https://nominatim.openstreetmap.org/).

QGIS features:

-Creating a map from a table containing the latitude and longitude columns: Plugins > GeoHealth > Import > XY to map.

-Geocoding a file containing addresses: Plugins > GeoCoding > GeoCoding.

After importing data, the second tab "Analyse" of the GeoHealth plugin proposes "Blur", "Incidence" and "Density" tools.

Data anonymization ("blurring")

Individual data such as epidemiological data could only be used in accordance with anonymity and, where appropriate, in agreement with the data protection authorities. Aggregation of individual data on an administrative scale is often sufficient to ensure anonymity and allow data dissemination. However, such aggregation leads to a loss of knowledge of the surrounding environment of each case. The GeoHealth plugin therefore offers an alternative method for blurring point data, implemented in the "Blur" tool. This tool has been designed for healthcare professionals to provide a simple method for blurring data prior to its dissemination for mapping and analysis.

The implemented blurring method consists of three steps (figure 7.2):

-create a buffer zone of a user-defined radius r around the cases locations; -randomly draw a new point in each buffer zone; -create a second buffer zone of the same radius r which will be the blurred zone. These new circular areas are the ones that must guarantee anonymity of the data in order to be transmitted. They necessarily include the initial point that cannot be retrieved (following the random draw). Any point in these blurred areas is at a maximum distance of 2 times the radius (2r), which indicates the resolution of the blurring. However, anonymity could not be effective if, for example, there is a single house in one blurred area. The blurring tool therefore proposes a test ("Stats" tab of the Blur tool window) to check the number of objects (here, the houses) in each blurred zone. This test is based on the use of a vector layer of buildings. It provides descriptive statistics including the minimum number of houses in all blurred areas. This test is proposed so that the user can assess the quality of the blurring and decide if the data can be disseminated. If this number is not satisfactory, the user can blur the data again by increasing the radius size.

QGIS features:

-Blurring point data: Plugins > GeoHealth > Analyse > Blur.

Creating an incidence or density map

The Incidence and Density tools in the Analysis menu are very similar in their design and objectives: specify the calculation settings (choice of layers and columns, indication of the ratio, name of the column to be created, name of the output file), choose the method of discretization and symbology of the map and display descriptive statistics. Two tabs are proposed according to the type of data input: a polygon layer containing the number of cases (generally per administrative unit) or a point layer of case location. The tool performs the calculation directly and adds the result to a new column of the attribute table, avoiding the user from switching to the edition mode to calculate new fields. The choice of symbology in the tool allows a fast display of the result, but does not prevent the user from fine-tuning the graphical representation.

QGIS features:

-Creating an incidence map: Plugins > GeoHealth > Analyse > Incidence.

-Creating a density map: Plugins > GeoHealth > Analyse > Density.

Importing data from the OpenStreetMap database

In a context of massive data availability and a willingness to release some of them, spatial data are becoming increasingly accessible. Among the outstanding projects, the OpenStreetMap Geographic Database (OSM) is a must-have resource for spatial health analysis. This global and open database, initiated in 2004, is enriched in a participative approach by the photo-interpretation of satellite images made available free of charge, by the integration of free datasets and also by field observations via dedicated applications on mobile devices (smartphones and tablets). A common way to contribute to OSM is to connect to its website (www.openstreetmap.org/), get identified (since each contribution is nominative) and then to draw objects (buildings, roads, points of interest, etc.) by photo-interpretation. In this case, the images made available to OSM will be used. By default, the OSM website displays Bing images that have been released for this purpose. Mapbox and DigitalGlobe companies also provide very high spatial resolution images for improving OSM database. They chose images in places, where high-resolution images were missing and where active contributors are registered in order to have, in turn, better mapping. Such images are also regularly provided when mapping is needed for humanitarian actions. Depending on the country, other accesses are provided. Finally, it is entirely possible to use one's own source of very high spatial resolution images (from drones or from satellites, such as Pleiades or Spot 6-7), acquired as part of a project, for example. Only project members will then use the image but the contributions to OSM will be accessible to all. Some organizations, such as Humanitarian OpenStreetMap Team (HOT: hotosm.org) and the NGO CartONG (cartong.org) were created to provide mapping support for humanitarian interventions. They coordinate the mapping tasks by getting people involved around the world through the Internet. Thus, in January 2010, a few hours after the heavy earthquake that hit Haiti (magnitude 7.0), the OSM community get mobilized. High spatial resolution satellite images showing the extent of the damage were provided within 48 hours and more than 600 people mapped the area in the first few months. OSM is regularly used for disease control projects. In 2016 and 2017, HOT and DigitalGlobe partnered to support the Clinton Health Access Initiative's malaria program by making satellite imagery available to accelerate mapping of houses and roads in endemic areas with little available geographic data. Another initiative based on the OSM project is the HealthSites website (https://healthsites.io/) which aims at creating a global database of health facilities. The dedicated interface helps to complete this data.

The OSM database is especially interesting for spatial analysis since it can be easily queried and directly imported in QGIS. This import is implemented in the QuickOSM plugin by indicating the object categories to be imported (based on OSM keys/values, e.g."Building/yes" for buildings), the spatial extent and the type of data (lines, nodes, relationships). This import produces a vector file that can be directly saved and analyzed in QGIS. This query-based import of OSM data directly through the QuickOSM plugin in QGIS is a real advantage for the use of OSM. Indeed, other methods of importing OSM are generally done on the whole dataset over a given range (country or region). These queries allow a lighter and faster download, and easier use since only useful data is acquired.

In addition to using the data available in the OSM database, a user can also build their own data in the OSM database to import and then use them in QGIS. It could be:

-on a small study area with no data: a few days of work will be enough to map a small area (i.e. a few villages),;

-on a large study area: it will then be necessary to involve many people by organising a mapping party and to coordinate this work as it can be done on HOT; -by adding vectorial data. For example, a health administration can integrate data on health facilities into OSM. It is also possible to integrate free vector datasets and remotely-sensed information.

Given this potential, its daily enrichment and its integration into the QGIS software via the QuickOSM extension, the OSM database offers multiple possibilities for spatial analysis in different fields, including health.

QGIS features:

-Importing OpenStreetMap data: Plugins > QuickOSM.

Environmental analyses

For studies related to health, QGIS is mainly used for mapping data. However, spatial analyses are increasingly required to understand the spatial heterogeneity of data (distribution and cluster analyses) or the effect of environmental factors on health status. The GeoHealth plugin does not yet offer tools for these advanced uses, which will have to be done with other QGIS tools and plugins. There are many applications and some of them can be described here as examples:

-Distance calculations. For a long time, these calculations were limited to direct distances between points. This can be done very quickly in QGIS with the tool "Distance Matrix" which allows calculating distances between points of the same vector layer or between those of two vector layers. For example, this tool can be used to calculate the distance between a localization layer for patients and a localization layer for healthcare facilities. It is then possible to calculate for each patient the minimum distance to a structure. To refine this calculation, it is preferable to use a road network and calculate the theoretical travel time or the shortest distance via roads. The "Road graph plugin" allows such calculation (this plugin is integrated in QGIS but must be checked beforehand in the plugin manager). For this purpose, one can download the road network of a study area using QuickOSM (key/value = highway/yes) and check if the completeness of the network is sufficient for the travel time or distance calculation.

-Proximity to landscape elements. The objective of the study could be to test whether proximity to a landscape element is linked to a larger number of cases (for instance, for a case-control study). These landscape elements could be suspected places of risk (e.g. wetlands and rivers for mosquito-borne diseases) or pollution emission sites. Some of these elements could be recovered from OSM. To test the effect of proximity to watercourses, it would first be necessary to import watercourses via QuickOSM (key/value = waterway/yes) and then create buffer zones around them for the distance to be tested. QGIS proposes two tools: "Fixed distance buffer " where the user will indicate the distance and "Variable distance buffer " where this distance can vary depending on a layer variable (for instance, this distance could vary depending on the category of the watercourses). An intersection between these buffer zones and the location of cases can then be performed to statistically compare whether the proportion of cases relative to controls is greater in the buffer zones. Nevertheless, a spatial correlation could be shown, but this is not necessarily a causal factor (the cause may be related to factors other than proximity to watercourses, this proximity would only be an indicator).

QGIS features:

-Distances between points: Vector > Analysis Tools > Distance matrix.

-Travelling time: Vector > Road Graph > Settings… -Buffer zones: Vector > Geoprocessing Tools > Fixed distance buffer or ou Variable distance buffer.

Export

Exporting data is easy in QGIS by saving a layer of data and selecting the appropriate format. Casual users who perform spatial analyses in QGIS before running statistical analyses in other software usually need to save the attribute tables only. For this purpose, the GeoHealth plugin offers this export function of the attribute table in a CSV format.

QGIS features:

-Export attribute table: Plugins > GeoHealth > Export > Attribute table. Input data (on the left side of the diagram) usually include epidemiological or observational data to be mapped and spatially analyzed. In the frame of this process, input data also include the data sources used to enrich OpenStreetMap (mainly satellite images). The central part of the diagram synthesizes the analyses conducted in QGIS with three plugins (GeoHealth, GeoCoding and QuickOSM). The outputs (on the right-hand side) of such analysis obviously include maps and, more often than not, data tables that can be statistically analyzed or used for dissemination of knowledge. This tutorial targets a wide audience, from beginners to experienced users of GIS softwares. It presents a series of exercises applied to Reunion Island, a French overseas province in the south-western Indian Ocean. This tutorial was realized with QGIS 2.18 and requires the installation of two plugins: GeoHealth and QuickOSM. They should be installed via the "Plugins Dialog" that can be launched from the Plugins menu (Manage and Install Plugins…). After installation, the GeoHealth plugin is accessible from the Plugin menu and the QuickOSM plugin via the Vector menu or its shortcut in the toolbars. They can also be directly used via the Processing Toolbox.

Installation of GeoHealth and QuickOSM plugins

Datasets

Sample data are available on the GitHub of the GeoHealth plugin to conduct this exercise: https://github.com/Gustry/GeoHealth/blob/master/sample_data/geohealth_sample_d ata_en.zip It contains:

-a point vector file (shapefile) representing fictional cases of two diseases on Reunion Island; -a table of addresses (in csv format) for testing geocoding (paragraph 7.3.4.1).

The other necessary data will be downloaded from the OpenStreetMap database using the QuickOSM plugin, when necessary.

Producing an incidence map with GeoHealth plugin

Objective: realize an incidence map using point data and administrative borders

Approach

Handling in QGIS 1. Importatio n of shapefiles

•

Open GeoHealth in menu: Plugin/GeoHealth.

• Select Import.

• Select Shapefile, and browse to the point shapefile called « fictional cases ». Once loaded, select Open. The file is displayed in QGIS.

2. Download of administrat ive units with QuickOSM plugin

• Click on the QuickOSM shortcut in the toolbar.

• Go to "My queries", where you will find several predefined queries, and click on Administrative boundary > Municipalities ( 8) extent.

• You must then select bbox (=bounding box) and the fictional cases layer will be proposed directly if it is already opened in QGIS. If other layers are proposed, choose fictional cases from the drop-down menu. Run the query.

• Such map should be visible:

In order to calculate the incidence, it is necessary to have the population size per district in the attribute table of the layer "Municipalities" downloaded from OSM. It is therefore necessary to check the existence of such column by right-clicking on the "Municipalities" layer in the layers panel and clicking on "Open Attribute Table ".

Incidence calculation with GeoHealth plugin

Using these two vector files (fictional cases and administrative boundaries), it is now possible to calculate the incidence of the fictional disease per district with the GeoHealth plugin:

• Go to the Analyse tab > Incidence.

• Then in the tab "Case and aggregation layers".

If only the two layers (fictional cases and municipalities) are opened in the QGIS project, they are directly proposed in the settings. Otherwise, select them from the drop-down menus. For the "Population field" select the population column (from the administrative boundary layer).

For the other settings, it is possible to:

• choose the denominator (a value of 100,000 inhabitants is given by default); • change the name of the column that will indicate the incidence (referred to by default as "incidence"); • choose the location and name of the new layer to be recorded or leave as a temporary file by default; • choose the symbology (colors, graduation mode and number of classes).

Results

Here is the result, with the default settings: Objective: geocode addresses (associate geographic coordinates to postal addresses in order to map them).

The GeoCoding plugin allows to geocode addresses directly in QGIS by querying either Google web services or Nominatim. This plugin requires an internet connection. Addresses (number, street, postal code, city) must be written one by one (it is not possible to geocode an address table at a time).

The exercise is based on the use of the pharmacy.csv file, which contains the addresses of drugstores in Saint-Pierre district in Reunion Island. This table is an extract of the SIRENE database (https://www.sirene.fr), a French open database of companies.

Approach

Handling in QGIS GeoCoding plugin is then accessible from the Plugin menu.

Geocoding of addresses

It is necessary to select first the database used for geocoding: Google or Nominatim.

• Go to Plugin / GeoCoding / Settings • Select Google as the Geocoder engine and validate Then the table containing addresses (pharmacy.csv) could be opened separately and each address could be copied one by one to the GeoCoding plugin. This table could also be opened in QGIS:

•

Go to Layer / Add Layer / Add Delimited Text Layer… • Select the pharmacy.csv file.

•

Indicate the CSV format.

• Select also the option "No geometry (attribute only table)".

•

Validate with OK.

Each address of the geo_address column should be copied and pasted in the GeoCoding plugin:

• Go to Plugin / GeoCoding / GeoCoding • Paste each address one by one (copied from the pharmacy.csv file) and validate with OK

• A file GeoCoding Plugin Results is created and each address is added to this file as it is geocoded.

•

This file could be saved as a shapefile: right click on the file name in the layers panel, browse to your folder and give a name to this new shapefile.

Tableau 7.2. Geocoding addresses with GeoCoding plugin

Blurring

Objective: "Blurring" of the location of point data to anonymize them (see subsection 7.2.3).

The GeoHealth plugin proposes a spatial anonymization method via its "blur" tool.

Approach

Handling in QGIS 1. Importation of shapefiles

•

Open GeoHealth in menu: Plugin/GeoHealth.

• Select Import.

• Select Shapefile, and browse to the point shapefile called « fictional cases ». Once loaded, select Open. The file is displayed in QGIS.

2. Verificatio n of the projection and eventual reprojectio n of data Since the blurring function involves the calculation of buffer zones, it must be verified beforehand that the layer to be blurred is in a projected coordinate system, in meters:

• Double-click on the fictional case layer in the Layers Panel to open the "Layer Properties" window.

•

Go to the "General" tab.

•

Verify the coordinate reference system (CRS).

In this exercise, the layer of fictional cases is in projection WGS84 (CRS 4326) and the coordinates are therefore in geographical degrees. This layer must be re-projected, in meters:

• Right-click on the layer and select "Save As...".

•

Enter a new name for the layer you want to create and choose the folder to save it.

•

Select the new CRS. In this exercise, for Reunion Island, it is WGS84/UTM zone 40S (EPSG: 32740).

Blurring •

Open the "Blur" tool: Analysis tab > Blur.

•

Select in the list "Point layer" the point layer to be blurred (which is in a projected CRS in meters).

•

Choose a blur radius (in meters).

•

If necessary, specify a name and location for the output file (e.g. "blurred_cases.shp").

•

In the "Advanced" section, it is possible to choose to enrich the attribute table with columns indicating the blur radius, X (longitude) and Y (latitude) coordinates of the centroid of the blurred area.

•

Click OK to start the calculation.

This query may take some time. You can get the error message "OverpassAPI execution time reached". In this case, it is possible to increase the execution time by editing the query: click on "Show query", and in the first line of the code, increase the value of the timeout from 25 by default, to 100 for example.

Then the query must be restarted.

Here is the result after downloading the OSM buildings:

Once the query is realized, the building layer must be projected in the same projection system as the blurred areas:

• Right-click on the layer name and select "Save as".

•

Select the new CRS (WGS84/UTM zone 40S (EPSG: 32740)).

•

Save the layer under a new name.

•

Confirm by clicking OK.

Blurring quality assessment

The calculation of the number of buildings in the blurred zones is also done in the tab "Blur":

• Go to the Stats tab.

•

Indicate the fuzzy layer and the statistical layer (here, the buildings layer).

•

Click on OK.

This calculation provides descriptive statistics of the number of buildings per blurred area and a graph of the number of buildings, in ascending order. It is thus possible to evaluate the quality of the blurring and, if it is not satisfactory, to re-launch it. The table and graph can be easily saved.

Tableau 7.3. "Blurring" of point data with GeoHealth plugin

Example of spatial analyzes for health studies

Objective: realize simple and useful spatial analyses useful for health studies:

-the calculation of a distance matrix: we will use the locations of doctors, downloaded from OSM; -the calculation of the shortest route, based on the OSM road network.

With the QuickOSM plugin, it is possible to specifically query objects of the OSM database. Here we will develop some examples of spatial analysis using this data.

Approach

Handling in QGIS This exercise requires the following data: fictional cases, doctors, the road network and the districts of Reunion Island.

Calculation of the distance matrix

A dedicated QGIS function allows to directly calculating distances between two point layers. In this example, we will calculate the distances between the locations of fictional cases (fictional_cases.shp previously used) and doctors.

As for blurring, we need a projection (CRS) in meters.

• Go to: Menu Vector / Analysis Tools / Distance Matrix

•

Choose the two layers of points (example: n patients and m doctors).

• Choose the type of matrix:

o Linear distance matrix where all combinations will be in line (n*m lines)

o standard distance matrix (with n rows and m columns).

• Specify the name and location of the output distance matrix to be saved. This matrix will be in .csv format.

The .csv file can be opened in Excel by importing: File/Import/, etc.

Calculation of the shortest path

QGIS integrates the Road graph plugin to calculate the shortest paths and travel times between points.

• Go to the Plugins Dialog and activate the Road graph plugin

• This one appears in QGIS as a panel with the name "Shortest path" (If this panel is not visible, go to the View/Panels menu and select "Shortest path").

• Open the OSM route file projected in WGS84 UTM 40S: highway_UTM.shp.

Define the plugin settings:

• Go to: Vector / Road Graph / Settings.

• Indicate the road network layer on which the paths will be calculated.

• It is possible to indicate the direction of roads for one-way roads and a speed field to calculate theoretical travel times.

access the editing interface and enter information. This editor provides several sources of satellite images that are used as a background image to help mapping.

Approach

Handling in QGIS 1. Registration • Go to the OSM website: https://www.openstreetmap.org.

• Click on "Register".

• Fill in the requested information and confirm the registration.

• Validate the registration by clicking on the link sent by email.

Open the ID editor

• Log on to OpenStreetMap (https://www.openstreetmap.org).

• Zoom in to the area to be edited.

• Click on the small arrow next to Edit. Then click Change with ID.

Switching the satellite images

In the editing interface, a satellite image is proposed as a background. By default, Bing images are visible. You can click "Background Settings" to select another background such as satellite images provided by MapBox and DigitalGlobe. It could be necessary to switch from one source to another to select the background that best corresponds to the mapping needs.

Contribution to OSM

OSM proposes three types of geometries: point, line and polygon.

• Switch to OSM edit mode and find an area where some buildings

are not yet mapped.

• Click on "Point" to add a point of interest.

• Left click on the map background to create this point.

•

For example, to add a doctor, go to the left and write "doctor" in the search window.

• Select the first choice. It is possible to fill in the other fields proposed according to the available information (e.g. address, name, etc.).

• Click on save.

• Indicate in the "Change group comment" field the nature of the edition and information on the geographical location (municipality, region, country, etc.).

To add linear information (e.g. a foot path):

• Click on "Line".

• Make a first left click to start editing and click on each change of direction.

• To end the line, double left click on the last point.

• Then add the keys and values of this line in the left-hand side of the interface, searching for "foot path".

• Save the changes by filling in the comment field as before.

Note: when adding a new route, it should be connected to the existing network as in the screenshot.

It is possible to modify the geometry of every element and to complete associated information by adding fields (keys). By rightclicking on the element, a toolbar appears: it allows to move the element, to change its direction, to make it straight or to delete it.

Figure 7 . 1 .

 71 Figure 7.1. GeoHealth plugin home window

Figure 7 . 2 .

 72 Figure 7.2. Blurring process of point data implemented in the "Blur" tool

Figure 7 .

 7 Figure7.3 summarizes a typical process of spatial analyzes for health studies. Input data (on the left side of the diagram) usually include epidemiological or observational data to be mapped and spatially analyzed. In the frame of this process, input data also include the data sources used to enrich OpenStreetMap (mainly satellite images). The central part of the diagram synthesizes the analyses conducted in QGIS with three plugins (GeoHealth, GeoCoding and QuickOSM). The outputs (on the right-hand side) of such analysis obviously include maps and, more often than not, data tables that can be statistically analyzed or used for dissemination of knowledge.

Figure 7 . 3 .

 73 Figure 7.3. Typical example of the use of QGIS software for mapping and spatial analysis of health data

Figure 7 . 4 .

 74 Figure 7.4. Access to the QGIS Plugins Dialog Window

Figure 7 . 5 .

 75 Figure 7.5. QGIS Plugins Dialog Window

Tableau 7. 1 .

 1 Creation of an incidence map with GeoHealth plugin 7.3.4. « Blurring » of point data with GeoHealth and QuickOSM plugins 7.3.4.1. Geocoding

Here is the result of the blurring with the default settings (500 meters radius): 4. Importatio n of the buildings of the study area with QuickOSM plugin

Once the point data is blurred, the blur tool proposes to calculate statistics to help assessing the quality of the blurring: here, it calculates the number of houses contained in each of the blurred buffer zones (see subsection 7.2.3).

A vector layer of buildings is necessary. It can be obtained by downloading the OpenStreetMap buildings using the QuickOSM plugin.

To reduce the calculation time, this exercise will only concern Saint-Pierre district.

In "Quick query", indicate:

• Key/Value = building/yes.

•

In = "Saint-Pierre".

•

Launch the query.

Start the routing calculation:

• In the "Shortest path" panel, select the starting and finishing points on screen or indicate their coordinates.

•

Click on Calculate.

•

The route is then displayed on the map.

Paths can be exported as vector files.

Tableau 7.4. Calculation of a distance matrix and the shortest path

Contribution to the OpenStreetMap database using satellite images

The objective of this section is to show how to contribute to the OSM database with the online editor "ID". Every contributor needs first to register in order to Default view of the Bing image in Edit mode

View of the DigitalGlobe image in Edit mode

It is also possible to specify an address manually for an image available on a server and accessible through a WMS (Web Map Service).

•

Click on the "Background Settings" and select "Custom";

To add a polygon (for example, a new building):

• Click on "Polygon".

•

Left click on a corner of the building to start editing and then click on each corner.

•

End with a double click on the last point.

•

Fill in the information on the left side of the interface by searching "building". The first proposal corresponds to a building without any other attribute (building = yes).

Once this building is completed, it is possible to right-click on the entity to access a toolbar of rapid edition, which allows to make it circular, to move it, to make it orthogonal, to duplicate it, to rotate it or to delete it.

For a building, it is recommended to give it an orthogonal shape.

When the object is finished, save the changes.

Note: the addition of roads and buildings, as shown here, are visible on the OSM map quickly.

Tableau 7.5. Online contribution to OpenStreetMap

In the OSM ID editor, some of the usual keyboard shortcuts also work: copy (ctrl + c), cut (ctrl + x) and paste (ctrl + v) shortcuts make it possible to duplicate or delete entities quickly. The shortcut (ctrl + z) is also used to cancel the last action.

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Zhaohui Huo

Antoine Bonnefont

Yiming Liang

Rana Farha

Michel Goldmann

Eric Saint-Aman

Hualong Xu

Christophe Bucher

Laurent Ruhlmann

Photovoltaic properties of supramolecular assemblies obtained by incorporation of Preysler's type polyoxometalate in a polycationic copolymer of porphyrin

est destinée au dépôt

Photovoltaic properties of supramolecular assemblies

obtained by incorporation of Preysler's type polyoxometalate in a polycationic copolymer of porphyrin

Introduction

Polyoxometalates (POMs) are a structurally diverse family of anionic metal -oxygen cluster anions constituted of metal elements in their highest oxidation states finding applications in analytical chemistry, medicine, homogeneous and heterogeneous catalysis, electronic, and materials science. [START_REF] Long | Polyoxometalates: building blocks for functional nanoscale systems[END_REF] Owing to their robustness and large number of metallic centers, POMs can undergo multi-electron photoredox reversible processes without structural alteration. 2 It is furthermore possible to use various type of structure (Lindqvist, Keggin, Dawson, Sandwich types...) and to change the type of heteroatom (V V , Nb V , Mo VI , W VI , …) involved in their structure to adjust the redox potentials. Preyssler-type POMs, K12.5Na1. 5[NaP5W30O110], have already been incorporated in photochromic [START_REF] Jiang | A novel photochromic multilayer based on preyssler's cluster[END_REF] and thermochromic [START_REF] Jiang | The first example of multilayer films with thermochromic properties[END_REF] composite films showing good reversibility in the coloration/decoloration process and stability. Preyssler-type POMs are furthermore far less investigated than the most common Dawson, Lindqvist or Anderson structures, especially in the context of photovoltaic.

The great heat stability and processability of POM-containing polymers make them indeed perfectly suited to the development of functional photovoltaic devices. Peng et al. have reported the first example of polymer featuring a conjugated photoactive organic skeleton [START_REF] Kang | Molecular and polymeric hybrids based on covalently linked polyoxometalates and transition-metal complexes[END_REF] and hexamolybdate type polyoxometalate (POM) clusters inserted into the main-chain or as side-chain pendant groups. [START_REF] Al | Towards Main-Chain-Polyoxometalate-Containing Hybrid Polymers: A Highly Efficient Approach to Bifunctionalized Organoimido Derivatives of Hexamolybdates[END_REF][7] These hybrid polymers exhibit intense visible absorption whose fluorescence is quenched by the integrated POMs. Such polymers have been used as key components within single-layer photovoltaic devices (indium tin oxide (ITO)/polymer/Ca configuration) featuring a power conversion efficiency (PCE) of 0.15%. 6b More recently, Peng et al. have reported a different type of organic-inorganic hybrid conjugated copolymer exhibiting different loadings of hexamolybdate type POMs covalently embedded in the main chain with imide-functionalized naphthodithiophene and 3,30-didodecyloxy bithiophene units presenting PCEs up to 0.31%. 7b The photovoltaic performance of this two hybrid materials are already very encouraging even if further improvements are obviously needed for applications. Several other covalently-linked POM-polymer hybrids have been described but their photovoltaic properties have not been reported. [START_REF] Wu | Covalently-linked polyoxometalate-polymer hybrids: optimizing synthesis, appealing structures and prospective applications[END_REF] The low photovoltaic efficiency reported in the articles mentioned above may be explained by the fact that POMs can be excited by light mainly under UV irradiations (O→M ligand-to-metal charge-transfer absorption band). This means that only a small fraction of the incoming light can be converted into electrical energy, which severely limits the applications of such materials for the construction of the photoelectric devices and may explain the small power conversion efficiency (PCE) reported by Peng et al. [START_REF] Al | Towards Main-Chain-Polyoxometalate-Containing Hybrid Polymers: A Highly Efficient Approach to Bifunctionalized Organoimido Derivatives of Hexamolybdates[END_REF][7] To address this issue, POMs can be associated via covalent, coordination or non-covalent bonding to porphyrin chromophore known to absorb visible light. 9-11 The introduction of POM-porphyrin hybrids into polymeric and surface supported materials is indeed a very promising approach toward functional devices with efficient photocatalytic or photovoltaic properties.

In line with this strategy, we have previously reported a straightforward and efficient electropolymerization procedure leading to mixed porphyrin-POM copolymer films, involving either Anderson, Dawson or Linqvist 12 type of POMs, with remarkable photocatalytic properties under visible light illumination.

A similar electropolymerization procedure was also implemented with dipyridyl ligands such as the 4,4'-bipyridine, but without polyoxometalate, to provide access to a series of cationic porphyrin-and viologen-based copolymers. In this case, the associated POM-porphyrin films could be prepared by exchanging the PF6 -counter ions with Keggin type polyanion [SiW12O40] 4-. This doping process was found to induce drastic modifications of the morphology evidenced by AFM. [START_REF] Hao | Supramolecular assemblies obtained by large counteranion incorporation in a well-oriented polycationic copolymer[END_REF] Such porphyrin-POM electrostatic assemblies could potentially be involved in photoinduced electron transfers between the porphyrin antenna (donor of electron) to the viologen spacers as well as the POM (acceptors of electron). These materials are thus promising for the development of photoelectric devices where the type of POMs can be modulated easily. In the first example published, [START_REF] Hao | Supramolecular assemblies obtained by large counteranion incorporation in a well-oriented polycationic copolymer[END_REF] only the fabrication of the electrostatic supramolecular structure was described, and the photocurrent generation as well as the photocatalytic behavior, under irradiation was not studied.

In the present paper, we have further exploited this strategy to incorporate a Preyssler-type POM ([NaP5W30O110] 14-; P5W30) into two kinds of electropolymerized poly-ZnOEP films, involving either simple rigid viologen (-py + -py + -) or more flexible bis-viologen, -py + -py + -(CH2)3-py + -py + -) spacers introduced between the zinc-β-octaethylporphyrin (ZnOEP) units. XPS analyses and UV-visible absorption measurements have been carried out before and after incorporation of P5W30. It was expected that this species could potentially behave in the polymer as an electron relay between the excited ZnOEP (donor) and the viologen (or bis-viologen) acceptors which could retard the charge recombination. We have systematically investigated photocurrent generation with poly-ZnOEP and of poly-ZnOEP/P5W30 under visible-light illumination in the presence of I3 -/I -used as redox mediator in acetonitrile as well as in aqueous medium.

Experimental

Materials. All solvents were of reagent grade quality and used without further purification. The zincβ-octaethylporphyrin (ZnOEP) and ligand 4,4'-bipyridine (4,4'-bpy) was purchased from Sigma-Aldrich and used without further purification. The 1,1''- (1,3-propanediyl) Electrochemistry and photoelectrochemistry. Voltammetric and electrochemical impedance measurements have been performed with a standard three-electrode system using a PARSTAT 2273 potentiostat. Glassy carbon or single-side coated indium-tin-oxide (ITO, SOLEMS, 25-35 /cm -2 ) electrodes, with a surface of about 1 cm 2 has been used as working electrode. A platinum wire has been used as auxiliary electrode. The reference electrode was a saturated calomel electrode (SCE). It was electrically connected to the solution by a junction bridge filled with the electrolyte.

Photoelectrochemical responses for films were obtained by on-off light illumination of a 300 W Xe arc lamp (with λ > 385 nm long pass filter) in acetonitrile containing 5 mmol.L -1 of I2 and 0.5 mol.L -1

of NaI with two-electrode system. In solution I2 reacts with I -to give I3 -. I3 -and I -anions act as reversible redox mediator and also as electrolyte in order to improve the conductivity and thus increase the current magnitude.

UV-visible Spectroscopic Measurements. UV-vis absorption spectra of the copolymers deposited on ITO or in DMF solution have been recorded on an Agilent 8453 spectrophotometer.

X-ray Photoelectron Spectroscopy (XPS).

XPS experiments were carried out on a RBD upgraded PHI-5000C ESCA system (Perkin-Elmer) with MgKR radiation (h =1253.6 eV) or Al KR radiation (h = 1486.6 eV). In general, the X-ray anode was run at 250 W and the high voltage was kept at 14.0 kV with a detection angle at 54°. The pass energy was fixed at 23. 5, 46.95, or 93.90 eV to ensure sufficient resolution and sensitivity. The base pressure of the analyzer chamber was about 5×10 -8 Pa. The sample was directly pressed to a self-supported disk (10 x 10 mm) and mounted on a sample holder then transferred into the analyzer chamber. The whole spectra (0-1100 eV) and the narrow spectra of all the elements with higher resolution were both recorded by using RBD 147 interface (RBD Enterprises, U.S.A.) through the Auger Scan 3.21 software. Binding energies were calibrated by using the containment carbon (C1s = 284.6 eV). The data analysis was implemented by using the RBD Auger Scan 3.21 software provided by RBD Enterprises or XPS Peak4.1 provided by Raymund W.M. Kwok (The Chinese University of Hongkong, China).

Synthesis of the poly-ZnOEP films. Electropolymerizations have been carried out under an argon atmosphere using a 0.1 mol.L -1 solution of NBu4PF6 in CH3CN/1,2-C2H4Cl2 (1/4) containing 2.5 × 10 -4 mol.L -1 of ZnOEP and 2.5 × 10 -4 mol.L -1 of 4,4'-bipyridine or bpy + -CH2-CH2-CH2-+ bpy•2PF6 -.

Electropolymerization is carried out at a fixed potential +1.90 V versus SCE at various deposition time.

However, iterative scan between -0.90 V and 2.00 V vs. SCE or -1.30 V and +2.00 V vs. SCE, in the case of 4,4'-bipyridine or bpy + -CH2-CH2-CH2-+ bpy•2PF6 -respectively, leads also to the formation of the co-polymer with viologen or bis-viologen spacers (Fig. S1 in ESI).

After electropolymerization, the modified working electrodes were systematically washed in CH3CN in order to remove traces of the monomers and of the excess of the NBu4PF6 salt present on the deposited films.

Synthesis of the hybrid films poly-ZnOEP/P5W30.

Poly-ZnOEP/P5W30 films have been prepared in two steps. First, the poly-ZnOEP polymers have been obtained using the protocol described below using a 0.1 mol.L -1 solution of NBu4PF6 in CH3CN/1,2-C2H4Cl2 (1/4) containing 2.5 × 10 -4 mol.L -1 of ZnOEP and 2.5×10 -4 mol.L -1 of 4,4'-bpy (poly-ZnOEP1) or bpy + -CH2-CH2-CH2-+ bpy•2PF6 -(poly-ZnOEP2) under an argon atmosphere (Scheme 1). In this case, electropolymerization was carried out in a potentiostatic regime at a fixed potential of +1.90 V versus SCE using various time of deposition (between 5 s and 180 s). After completion of the polymerization, the ITO electrodes were systematically washed with acetonitrile to remove traces of the monomers and of the salt present in the film. Second, after drying, P5W30 was incorporated by metathesis, which involved exchanging the PF6 -counter anions by immersion of the modified electrodes in 0.1 mmol.L -1 aqueous K12.5Na1.

Electrochemical quartz crystal measurement (EQCM/QCM).

A QCA-922 (SEIKO EG&G instrument) system combined with Versa STAT 3 was used for carrying out simultaneous electrochemical quartz crystal (EQCM) and cyclic voltammetric measurements. The electrochemical cell was assembled in a glove box using an ITO AT-cut quartz crystal resonator (mirror finished; resonant frequency, 9.08 MHz ± 50 kHz; A=0.2 cm 2 ; SEIKO EG&G., LTD) as working electrode, a platinum wire as counter electrode, and an Ag/AgCl wire as a quasi-reference electrode. The solution used here is the same as the one used for electropolymerization of the copolymers on larger ITO electrodes. Iterative scans were conducted at a scan rate of 100 mV s -1 at room temperature with simultaneous recording of the quartz resonance frequency. The change of the quartz resonance frequency (Δf) was converted into the mass change (Δm) on the ITO-coated quartz during iterative cycling by applying Sauerbrey's equation (Eq. 1): Δf = -2f0 2 .Δm/A(μ⋅ρ) 1/2 (Equation 1)

where f0 is the resonant frequency of the fundamental mode, ρ is density of the crystal (2.684 g.cm -3 ),

A is working area (0.2 cm 2 ) of the ITO quartz crystal resonator, μ is shear modulus of quartz (2.947×10 11 .m -1 .s -2 ). The Sauerbrey's equation (Eq. 1) can be used to calculate the mass of deposit Δm since our deposition yields a rigid and evenly distributed mass on the surface of the resonator, and the relative frequency variation is less than 2 % of its absolute value.

Results and Discussion

Fabrication and characterization of poly-ZnOEP films with viologen or bis-viologen spacers

Electropolymerization of poly-ZnOEP films with viologen or bis-viologen spacers monitored by EQCM

The reactivity of oxidized porphyrins can be advantageously exploited to generate a wide range of poly-porphyrin materials as long as a bifunctional nucleophile such as a 4,4'-bipyridine is used. [START_REF] Al. Ruhlmann | A Polycationic Zinc-5,15dichlorooctaethylporphyrinate-viologen Wire[END_REF] Electropolymerization is carried out at a sufficiently high positive potential to produce doubly oxidized porphyrins (dication) which are readily reacting with the viologen-containing spacers to produce the targeted copolymers. Mono-substituted porphyrins can be obtained from the mono oxidized radical cations but electropolymerization requires the formation of porphyrin dications, most probably due to kinetic issues (porphyrin dications react more rapidly with pyridyl groups than the radical cation). The previously reported E(ECN mesoECB)nE process has been proposed to explain the electropolymerization process where CN meso relates to the nucleophilic attack at the meso position of the porphyrin to form an isoporphyrin intermediate. 16b, [START_REF] Schaming | Easy methods for the electropolymerization of porphyrins based on the oxidation of the macrocycles[END_REF] This latter is then oxidized (electrochemical step) and the hydrogen atom initially located on the meso-carbon is released (chemical step CB). The corresponding global reaction is written in Eq. 2 assuming that only the bisubtitution on the ZnOEP porphyrin occurs at two of the four meso positions (cis or trans bisubstitution: substitution on the carbons C5 and C10 or C5 and C15 respectively, Scheme 1):

(Equation 2)

The copolymer can thus only be obtained after generation of the porphyrin dications by iterative scans (Fig. S1, ESI) or by potentiostatic electrolysis at +1.90 V vs. SCE (Fig. 1). Previous studies have shown that scanning the electrode potential between -0.9 V and +2.0 V or between -1.3 V and +2.0 V vs.

SCE for bpy or bpy + -CH2-CH2-CH2-+ bpy•2PF6 -respectively, allows to reduce the protons released by the electropolymerization. H + accumulates in solution when scanning is limited to the positive potential window or when polymerization is achieved in an electrolysis regime at an applied potential of +1.9 V vs. SCE. Even in these cases, we found that H + does not affect the coating process. We have also demonstrated, mainly by UV-vis absorption spectroscopy, that the metal ion remains in the porphyrin ring during electropolymerization. In support of this assertion, we found that the UV-visible absorption spectra of mother solutions, containing ZnOEP and the nucleophilic spacer (4,4'-bpy or bpy + -CH2-CH2-CH2-+ bpy 2PF6 -), shows no evidence of demetallation of the starting ZnOEP even after deposition of several films or that the spectroscopic signature of ZnOEP is retained in films produced from the iterative method.

Electropolymerizations could thus be carried out under an argon atmosphere by iterative scans performed in 0.1 mol L -1 solutions of tetrabutylammonium hexafluorophosphate in CH3CN / 1,2-C2H4Cl2 (1 : 4) containing ZnOEP (0.25 mmol.L -1 ) and a pyridine-based nucleophile such as bpy or bpy + -CH2-CH2-CH2-+ bpy 2PF6 -(0.25 mmol.L -1 ). The evolution of the CV curves recorded during the electropolymerization of ZnOEP with 4,4'-bipy and bpy + -CH2-CH2-CH2-+ bpy 2PF6 -is shown in the ESI section (Fig. S1).

Deposition of poly-ZnOEP1 and poly-ZnOEP2 onto the electrode surface can also be achieved in a potentiostatic regime upon setting the electrode potential at +1.90 V vs. SCE. The associated mass change (Δm) was calculated from the quartz resonance frequency (Δf) recorded at an ITO AT-cut quartz crystal resonator of an Electrochemical Quartz Crystal Microbalance (EQCM). Deposition of the polymer on the quartz resonator during electrolysis is revealed by a large decrease of the quartz resonance frequency (Δf) over time. The associated changes in mass at the working electrode could be quantified from the changes in the quartz resonance frequency (Δf) using Sauerbrey's equation. [START_REF] Bruckenstein | Experimental aspects of use of the quartz crystal microbalance in solution[END_REF] Calculations performed after 180 seconds of electrolysis led to loadings of 7.9 and 5.7 µg.cm -2 for poly-ZnOEP1 and poly-ZnOEP2, respectively. The calculated surface coverage  in mole of repeat unit for the polymer were 7.571× 10 -9 mol.cm -2 for poly-ZnOEP1 (repeat unit: -(ZnOEP-py + -py + )-2PF6 -) and 4.68 × 10 -9 mol.cm -2 poly-ZnOEP2 (repeat unit: -(ZnOEP-py + -py + -CH2-CH2-CH2-py +py + )-4PF6 -). It shows that in the same conditions, poly-ZnOEP2 is less deposited.

UV-visible spectroscopy

The UV-visible absorption spectra of the ZnOEP monomer in solution and of the copolymers deposited on ITO are shown for comparison in Figure 2. These data are also collected in Table 1. This superposition reveals that the Soret band, attributed to the main porphyrin-based -* electronic transition, is much broader and more red-shifted for the two copolymers poly-ZnOEP1 and poly-ZnOEP2 (onto ITO electrode) than for the ZnOEP (Table 1). Such modifications can be interpreted upon considering the existence of intra-and intermolecular exciton-coupling between the porphyrin units within the polymer. 19 These changes can also be explained by a greater deformation of the macrocycles within the copolymer. Furthermore, the red-shift of the Soret band can also be attributed to the electron-withdrawing effects of the viologen substituents on the porphyrin rings. The films produced by electropolymerization were found to be fully soluble in DMF. Analysis of the resulting solutions by UV-Vis absorption spectroscopy revealed a much sharper Soret band than that recorded on the solid film, the latter effect being clearly more pronounced for poly-ZnOEP2 (Fig. 2B) than for poly-ZnOEP1 (Fig. 2A). Such difference has been attributed to the existence of weaker exciton-coupling between porphyrins in poly-ZnOEP2, likely due to the larger flexibility of the polymer.

Similar optical spectra were obtained using films obtained using applied potential of 1.9 V vs. SCE (Fig. 3). We have also examined the effect of various experimental parameters used for electropolymerization on the properties of the ITO coated polymers. Different modified electrodes have been grown at +1.90

V vs. SCE upon varying the deposition time (Fig. 3). Plotting the absorbance of the Soret band recorded for poly-ZnOEP1 and poly-ZnOEP2 as a function of deposition time (inset of

Cyclic voltammetric investigations of the copolymeric films

Electroactive polymers deposited on ITO surfaces have been characterized by electrochemical methods. After deposition of the polymers at fixed potential (+1.90 V vs. SCE), the modified electrodes were removed from the electrochemical cell, washed with CH3CN and used as working electrode in a clean electrolytic solution containing only the solvent and the supporting electrolyte (Fig. 4). A detailed discussion on the redox behaviour of poly-ZnOEP1 can be found in a previous report. [START_REF] Al. Ruhlmann | A Polycationic Zinc-5,15dichlorooctaethylporphyrinate-viologen Wire[END_REF] In the present study involving deposition at an applied potential of +1.9 V vs. SCE, the investigation has been conducted in a 1,2-C2H4Cl2/CH3CN (4/1) solution (same mixing solvent used for the electropolymerization). The reduction peaks centered at ca. 0.04 V (peak I), -0.24 V (peak II) and -0.55 V (peak III) corresponds to the first (V 2+ →V +• , peak I) and second reduction (V +• →V 0 , peaks II and III) of the viologens spacers ( The splitting of the wave attributed to the reduction of the viologen units (peaks II and III) most probably arises from the specific copolymer's structure and from communication/interaction processes occurring between neighboring redox active fragments (viologen radical cations, V +• ) in the chain or between chains giving intra-or intermolecular interactions.

The poly-ZnOEP2 film was also studied in the electrolyte used for electropolymerization (1,2-C2H4Cl2/CH3CN (4/1) solution (Fig 4B and Fig. S2B). [START_REF] Huo | Alternating electro-copolymerization of zinc--octaethylporphyrin with a flexible bipyridinium[END_REF] The first well defined, bell-shaped, reduction wave observed at -0.12 V vs. SCE (peak I) is attributed to the formation of viologen radical cations in the polymer (V 2+ →V +• ). The second viologen-centered electron transfer (V +• →V 0 ) is then observed as two successive waves at -0.52 V and -0.66 V vs. SCE (peaks II and III).

The wave splitting is not observed for the first electron transfer leading to the formation of the bisradical V + • -(CH2)3-V + • (peak I) but only on the following redox processes yielding V + • -(CH2)3-V 0 and V 0 -(CH2)3-V 0 in the copolymer poly-ZnOEP2 (peaks II and III respectively) as already observed in the case of poly-ZnOEP1. It should also be mentioned that similar behaviors have been observed when investigating poly-ZnOEP1 and poly-ZnOEP2 films (Fig. 4 and Table 2) in CH3CN (0.1 mol.L - 1 TBAPF6).

Film Morphology (Atomic Force Microscopy)

The morphology of poly-ZnOEP1 and poly-ZnOEP2 obtained in potentiostatic regime at Eapp = 1.9

V vs. SCE during 180 seconds has been scrutinized by AFM (Fig. S3). Both copolymers appear on the surface as tightly packed coils with an average diameter of ca. 80-100 nm. The rms surface roughness of the two films are estimated at 2.4 nm for poly-ZnOEP1 and 2.9 nm for poly-ZnOEP2 (calculated from an area of 25.0 µm 2 ), which are is in agreement with the morphology already depicted for our previous copolymers.

Thickness measurement of polymeric films

The thickness of these films (Fig. 5) have been estimated upon scratching the film with a metallic tip and comparing the height on each side of the scratch (Fig. 5BC). The thickness measured by AFM was found to increase with the deposition time to reach an upper limit value. This trend is reminiscent of the data recorded by UV-Vis absorption spectroscopy. For deposited time of 180 seconds; the thickness of both deposited copolymeric film gave about 31 nm and 25 nm for poly-ZnOEP1 and poly-ZnOEP2, respectively.

X-ray photoelectron spectra (XPS)

XPS analyses have been carried out to determine the elemental composition of the two films. This type of characterization has been already used to determine the elemental composition of various porphyrins based films. XPS is not has proved very efficient to reveal the presence of given elements and their oxidation state within the films. The presence of C, N, O, Zn, Na, P, and F enables to confirm the presence of poly-ZnOEP1/P5W30 (red line, Fig. 6). In poly-ZnOEP1 film, the Zn 2p3/2 (1022.8 eV)

is assigned to the zinc atom in ZnOEP. Two different signals attributed to nitrogen atoms with different chemical states are observed at 402.6 eV, attributed to the ammonium counteractions, and at 399.7 eV due to the viologen spacers and the nitrogen atoms present in the porphyrin as well the terminal pyridine (quite small quantity) respectively (Fig. 6C, black curve and Fig. S5).

The P 2p3/2 (136.6 eV, Fig. 6E, black curve) and F 1s (686.8 eV, Fig. 6I black curve) is ascribed to counter ion PF6 -. While O 1s signal (532.9 eV) comes from H2O on the copolymer surface (Fig. 6D, black curve). Similar behavior has been obtained for poly-ZnOEP2 film (Fig. S4 and Fig. S6).

Fabrication and characterization of two poly-ZnOEP-Preyssler type-POM composite films

Fabrication the poly-ZnOEP-Preyssler type-POM composite films

Poly-ZnOEP/P5W30 films have been prepared in two steps. The poly-ZnOEP copolymers have been showing strong interactions between the two subunits. It can be explained by the close contact as well as the overlapping of orbitals between porphyrin and POMs. 11

QCM to monitor [NaP5W30O110] 14-/PF6 -exchange

The kinetics of incorporation of [NaP5W30O110] 14-into poly-ZnOEP1 and poly-ZnOEP2 was estimated by in-situ QCM measurements using QCM electrodes covered with either poly-ZnOEP1 or poly-ZnOEP2 films in contact with the K12.5Na1.5[NaP5W30O110] aqueous solution. The frequency change was measured as a function of the soaking time. The frequency response associated to the insertion of [NaP5W30O110] 14-within a poly-ZnOEP1 film (obtained at applied potential: +1.9 V vs. SCE during 180 s) is depicted in Figure 8. The mass change due to the [NaP5W30O110] 14-/PF6 -exchange in the film during the one, two and three hours soaking in the K12.5Na1.5[NaP5W30O110] aqueous solution could be estimated after rinsing the film with ultrapure water to remove weakly adsorbed species.

Three parameters could be evaluated from this plot: Δf1, Δf2 and Δf3 which corresponded to the variation of frequency induced by [NaP5W30O110] 14-/PF6 -exchange in the film during the one, two and three hours soaking in the K12.5Na1. 5[NaP5W30O110] aqueous solution in the case of poly-ZnOEP1 film.

A decrease of the frequency value corresponds to an increase of the mass at the sensing area. The mass changes after one hour, two hours, and three hours of soaking of poly-ZnOEP1 film have been estimated to be 0.618 µg cm -2 , 0.912 µg cm -2 and 1.101 µg cm -2 , respectively. However, after two hours (2 successive soaking cycles of 60 minutes), we observed the decrease of the frequency also during the rinsing using water showing that one part of the mass change probably came also from H2O which adsorbed also on the surface of poly-ZnOEP1/P5W30 hybrid film. This variation of the frequency allows us to calculate the mass of water which is adsorbed. For poly-ZnOEP1/P5W30 hybrid film the mass change due to the [NaP5W30O110] 14-incorporated on the surface of poly-ZnOEP1 film calculated (Fig. 8) were 0.618 µg cm -2 , 0.912 µg cm -2 and 0.990 µg cm -2 after the soaking time of one hour, two hours, and three hours, respectively. The quantity of adsorbed water can also be calculated from the frequency response of QCM sensor when rinsing with water (fH 2 O) and is estimated to be 0.111 µg cm -2 after 3 hours (3 successive soaking cycles of 60 minutes).

The frequency response of an ITO AT-cut quartz crystal resonator modified with poly-ZnOEP2

(deposited at applied potential of +1.9 V during 180 s) recorded during the exchange of PF6 -by

[NaP5W30O110] 14-is shown in the ESI section (Fig. S7). The incorporation of [NaP5W30O110] 14-is found to proceed faster in poly-ZnOEP2 than in poly-ZnOEP1, most probably due to the larger charge density of poly-ZnOEP2. The effect of water adsorption was also found to be larger for poly-ZnOEP2

than for poly-ZnOEP1.

In the case of poly-ZnOEP1, because the copolymer present two time lower charges in comparison of poly-ZnOEP2 (-py + -py + -2PF6 -for poly-ZnOEP1 vs. -py + -py + -(CH2)3-py + -py + -4PF6 -for poly-ZnOEP2). The maximum of adsorption of of P5W30 need more time, around 3 hours (Fig. 7B).

The molar ratio between [ZnOEP] and [P5W30] in the poly-ZnOEP1/P5W30 and poly-ZnOEP2/P5W30 films has been calculated from the EQCM and QCM data. The molar ratio

[ZnOEP]/[P5W30] could be estimated after one hour to be 37.5 for poly-ZnOEP1/P5W30 and 32.9 for poly-ZnOEP2/P5W30. These values are then found to decrease with time to reach 21.1 and 20.8 after three hours (Table S1). These results confirm the partial exchange of PF6 -by [NaP5W30O110] 14-as well as hydration of the film. aqueous solution; see Figure 8).

Cyclic Voltammetric investigations of the hybrid films poly-ZnOEP/P5W30.

The effect of the counteranions (PF6 -or [NaP5W30O110] 14-) on the electrochemical signature of poly-ZnOEP was assessed upon dipping for 1 hour the ITO electrodes coated with either poly-ZnOEP1 or poly-ZnOEP2 in an aqueous solution of K12.5Na1.5[NaP5W30O110] (10 -4 mol.L -1 ) followed by washing with water (10 mL). The corresponding electrochemical data are collected in Table 2.

One key finding is that the CV of poly-ZnOEP1/P5W30 (Fig. S8A and Fig. S9A) and poly-ZnOEP2/P5W30 (Fig. S8B and Fig. S9B) recorded in acetonitrile (0.1 mol.L -1 TBAPF6) are similar to those recorded in the same conditions for poly-ZnOEP1 and poly-ZnOEP2, which supports the conclusion that the exchange of PF6 -by [NaP5W30O110] 14-only occurs at the surface.

Another interesting point is that the reduction of P5W30 in solution, TBA14[NaP5W30O110] shows three successive reduction processes in acetonitrile system (Fig. S10). Thus, the reduction processes associated to [NaP5W30O110] 14-were not detected in the case of poly-ZnOEP1/P5W30 or poly-ZnOEP2/P5W30. This behavior may also be explained by the kinetic of the electron transfer through the film between the P5W30 and the porphyrin subunits which might be drastically slowed down. Such behavior has been already reported, even in solution, with various POMs-porphyrin systems. 11b,e,13,21

To understand the photocurrent generation, it is also of interest to look at the current potential curves obtained in acetonitrile using Na + I -as electrolyte instead of 0.1 mol.L -1 TBAPF6 (Fig. 9).

We found that the presence of I -in the electrolyte leads to a significant cathodic shift of the waves corresponding to the reduction of the viologen units, which reflects the importance of the ion-pairing effects in organic media.

Note however, that in the anodic region, the oxidation current of I -is masking the oxidation peak of porphyrin because of the large excess of I -(0.5 mol.L -1 ) present in solution. In addition, the oxidation potential of the porphyrin unit remains nearly unchanged using various type of electrolyte. Thus, measurement of the first oxidation potential of ZnOEP subunit of poly-ZnOEP1/P5W30 (Fig. 9A, Fig. S11A and Fig. S12A) and poly-ZnOEP2/P5W30 are carried out in acetonitrile containing 0.1 mol.L -1 TBAPF6 (Fig. S11B, Fig. S12B and Fig. S13).

The current potential curves of poly-ZnOEP1/P5W30 were also measured in aqueous solution containing NaI (0.1 mol.L -1 ). As in acetonitrile, three reduction waves due to the reduction of the viologen spacers were observed at slightly higher potential than in acetonitrile (Fig. 9B and Table 2).

X-ray photoelectron spectra (XPS) of poly-

Film Morphology (Atomic Force Microscopy)

similar topographic images with rms surface roughness ranging from 2.2 nm for poly-ZnOEP1/P5W30

to 2.0 nm for poly-ZnOEP2/P5W30 (Fig. 10). The deposited copolymers appear on the surface as tightly packed coils with an average diameter of ca. 70-100 nm.

Photoelectrochemical properties

The photoelectrochemical properties of the poly-ZnOEP1 and poly-ZnOEP2 hybrids films (e.g. the photocurrent generation and the photovoltage under open circuit conditions) have been investigated

both in acetonitrile and in aqueous solutions containing I3 -5 mmol L -1 and I -0.5 mol L -1 as redox mediators. Sodium iodide also acts as a supporting electrolyte ensuring a good conductivity of the medium.

Influence of the solvent

Figure 11 shows the photocurrent response of poly-ZnOEP1 and poly-ZnOEP2 hybrid films obtained in acetonitrile and in aqueous solutions. In the absence of POM, the poly-ZnOEP1 and poly-ZnOEP2

films were found to exhibit a positive photocurrent involving the oxidation of I -in acetonitrile (Figures 11A and11C). The photocurrent response was moreover found to be prompt, steady and reproducible even after four hours off on-off cycles involving irradiation with a Xenon lamp.

Light Irradiation was also found to induce a cathodic shift of the open circuit potential values measured for poly-ZnOEP1 and poly-ZnOEP2 on ITO electrodes (Table S3). The energy diagram corresponding to the photooxidation of I -will be discussed in more details later in Figure 14 A. Briefly, after absorption of a photon, an electron transfer occurs from the excited ZnOEP to the viologen spacer and then to the ITO.

The oxidized ZnOEP can then in turn be reduced by I -, while I3 -is reduced at the platinum counter electrode.

Interestingly, the signs of the photocurrent at 0.0V bias potential and of the photovoltage are inverted when the same modified electrodes are used (poly-ZnOEP1 and poly-ZnOEP2), in aqueous solution (Fig. 11B and Table S3). This reveals an inversion of the electron transfer direction under illumination in aqueous solution according to the energy level diagrams displayed in Figure 14B. The origin of this inversion is still unclear at the present stage, it might be tentatively attributed to the influence of the solvent on the electron transfer kinetics between the poly-ZnOEP and the ITO electrode (see the EIS results below).

Influence of the type of spacer

In the absence of POM, the best photoelectrochemical performances have been obtained with poly-ZnOEP2 featuring a bis-viologen spacer. In acetonitrile, the photocurrent measured at 0.0V bias potential vs. the Pt counter electrode and the photovoltage measured under open circuit conditions have been found to be significantly better for poly-ZnOEP2 (ca. 16 µA.cm -2 and -73 mV) than for poly-ZnOEP1 of (ca. 9 µA.cm -2 and -20 mV) (Table S3). This suggests that the presence of a bis-viologen spacer is beneficial for the charge separation in the polymer film. The positive role of the bis-viologen spacer is also confirmed by measurements carried out in aqueous solution, where a photocurrent as high as -80 µA.cm -2 could be obtained with poly-ZnOEP2 (compared to ca. -6 µA.cm -2 for the polypolymer).

Optimization of the soaking time in K12.5Na1.5[NaP5W30O110] solution

The influence of the POM on the photoelectrochemical properties of the poly-ZnOEP1 and poly-ZnOEP2 hybrids films has been studied both in acetonitrile and in water. solution for fixed durations. In these conditions, K12.5Na1. 5[NaP5W30O110] is not expected to be excited.

The photoelectrochemical properties have been initially investigated in acetonitrile. We found that the magnitude of the photocurrent response of the poly-ZnOEP1/P5W30 and poly-ZnOEP2/P5W30 films is significantly increased in the presence of the polyoxometalate P5W30. At 0.00 V bias potential, the photocurrent was found to be 3. Similar experiments carried out in water led to less clear-cut conclusions. The magnitude of the photocurrent of poly-ZnOEP1/P5W30 was enhanced by a factor of two after soaking for 60 minutes in P5W30 solution (Fig. 11B, Fig. 12 and Fig. S15A), but a significant decrease of the poly-ZnOEP2/P5W30 photocurrent by a factor four could be observed (Fig. S14B and Fig. S15B). This decrease can be tentatively attributed to a modification of the structure of the polymer film in the presence of the POM, resulting in a less efficient charge transfer between the ITO electrode and the film.

Electrochemical impedance spectroscopic analysis

Electrochemical impedance spectroscopy (EIS) has been widely used to investigate the kinetics of electronic or ionic processes in dye-sensitized solar cells. 23 By analyzing the current response to a small amplitude potential perturbation from the steady state, the charge transfer resistance Rct associated to the electron transfer at the electrode/electrolyte interface as well as the parameters of the charge transport in the porous electrode and of the recombination reaction can be extracted. In the present work, EIS measurements have been carried out in aqueous and in acetonitrile solutions containing I3 -(5 mmol.L -1 ) and I -(0.5 mol.L -1 ) in order to get further insights into the rate and efficiency of the electron transfer processes. The experimental data could be fitted within good approximation using the equivalent circuit displayed in Figure 13C. The Nyquist plots obtained for poly-ZnOEP1/P5W30 with and without illumination at a bias potential of 0.0 V in acetonitrile and in water are displayed in Figure 13 and the curve fitting data obtained with poly-ZnOEP1/P5W30 are summarized in the Table 3. Two semicircles are observed in the Nyquist plot of poly-ZnOEP1/P5W30 in acetonitrile. The first low resistance (from 300 to 430 Ω) and high frequency arc is attributed to the charge transfer processes at the ITO/poly-ZnOEP1/P5W30 interface modeled by the parallel combination of the charge transfer resistance RITO film and capacitance CITO/Film. The second semicircle with higher resistance (from 780 to 1440 Ω) at lower frequency is mainly assigned to the charge transfer process between poly-ZnOEP1/P5W30 and the I3 -/I -species in the electrolyte; it results from the coupling of the chemical capacitance of the polymer film Cfilm in parallel with the charge transfer resistance of the film to the redox species in the electrolyte Rct film. In contrast, the Nyquist diagrams obtained in aqueous solution (Figure 13B) feature only one semi-circle with a much higher value of the charge transfer resistances (from 19 to 130 kΩ) than the ones measured in acetonitrile and that can be assigned to the electron transfer at the ITO/poly-ZnOEP1/P5W30 interface. The origin of the huge increase of RITO/Film in aqueous solution might be tentatively attributed to a modification of the structure of the polymer film induced by the solvent. Also, it should be noticed that the much larger value of RITO/Film compared to Rct film (Table 3) might be one of the reasons for the inversion of the direction of the electron transfer observed in aqueous solution. Obviously, the low frequency part of the impedance spectra obtained in aqueous solution without illumination cannot be fully reproduced by the fit using the equivalent circuit displayed in Figure 13C, revealing that the charge transfer in the electrochemical system is affected by another process below 0.1 Hz.

The values of Rct film and RITO/film reported in Table 3 happen to be significantly affected by the illumination, as revealed by the significant decrease of the diameter of the arcs observed under illumination. The drop in the charge transfer resistance value RITO film observed both in aqueous solution and in acetonitrile might be attributed to a local increase of the temperature due to the illumination which accelerates the electron transfer kinetic between the ITO and the copolymer. The different effect of light on the Rct film value in aqueous solution and in acetonitrile might arise from the local variation of the I3 -concentration induced by the photocurrent generation (the local I - concentration being approximately constant). In this case, the increase of the local concentration in I3 - by the anodic photocurrent in acetonitrile will tend to decrease the value of Rct film while in aqueous solution the consumption of I3 -in the vicinity of the electrode will rather provoke an increase of Rct film as observed in Table 3.

A detailed analysis of the impedance spectra provides further insights on the role of the POM in the photoelectrochemical system. Clearly, the incorporation of the POM results in a significant decrease of the RITO/Film in aqueous solution and in acetonitrile, revealing that the presence of the POM accelerates the electron transfer kinetics between the ITO and the film and thus contributes to the enhancement of the photocurrent generation. It should also be mentioned that the Rct film value calculated in acetonitrile decreases in the presence of the POM, suggesting that in this case the kinetics of the recombination reaction with the photogenerated I3 -might also be enhanced by the POM.

Finally, the Nyquist plots recorded for poly-ZnOEP2/P5W30 (Figure S16) exhibit only one semi-circle in aqueous solution and in acetonitrile, making the determination of the RITO film and Rct film values more difficult. Overall, similar trends can be observed with poly-ZnOEP1/P5W30 and poly-ZnOEP2/P5W30 in acetonitrile.

In aqueous solution, one remarkable feature is the strong decrease of the impedance semicircle diameter of the poly-ZnOEP2 film in the presence of light which is compatible with the large photocurrent values. In this particular case, the diameter of the impedance semicircle is increased when the POM is incorporated, revealing a decrease of the electron transfer kinetics. Under illumination the BIAS potential was 0.00 V vs. OCP. In the dark, the BIAS potential was the OCP of the same film under illumination vs. SCE.

Energy diagram of the electron transfer processes

The anodic photo-electric current measured with poly-ZnOEP1/P5W30 and poly-ZnOEP2/P5W30 film in acetonitrile involve the following processes: i) the band-gap excitation from HOMO to LUMO of the ZnOEP macrocycle under illumination, ii) electron transfer from the LUMO of ZnOEP to P5W30, while I -transfer one electron to the HOMO of ZnOEP, iii) the reduced P5W30 mediates the reduction of the viologen (or bis-viologen) dications, iv) viologen (or bis-viologen) cation radicals transfer the electron to ITO electrode (Fig. 14A).

The potential of the first oxidation of the ZnOEP (P) species in the film provides a direct measurement of the energy of the HOMO level. The potential of the excited porphyrin can be calculated by subtracting the excitation energy from the ground state oxidation potential of the porphyrin, which is correlated with the ability of the excited porphyrin to transfer electrons to P5W30.

E(P +• /P * ) = E(P +• /P) -ES0  S1 (Equation 4)

From the electron affinity, the Ec edges of ITO electrode surface are estimated to be ca.

Conclusion

In summary, two poly-ZnOEP/P5W30 films have been prepared through the incorporation of

[NaP5W30O110] 14-in poly-ZnOEP films involving either rigid/short viologen linkers or flexible/long bis-viologen linkers introduced between the ZnOEP macrocycles. We found that both poly-ZnOEP/P5W30 composite film electrodes feature higher response than the POM-free poly-ZnOEP electrodes in acetonitrile. This can be attributed to P5W30 acting as an intermediary between exited ZnOEP and spacers.

Interestingly, the direction of the electron transfer depends strongly of the solvent, the photocurrent being anodic in acetonitrile and cathodic in aqueous solution, using the same modified electrodes.

Impedance measurements also indicate that the presence of the P5W30 improve the electron transfer kinetics between the ITO surface and the film and thus contributes to the enhancement of the photocurrent generation.

Monitoring the thickness of the film is critical for the photocurrent-generation efficiency, probably due to the modification in conductivity of the deposited polymer.

Further developments must address in particular the improvement of the conductivity of the film. In situ measurement of the conductivity will be developed in order to have better understanding about this point. The overall conversion efficiency  of the sealed cell need also in the future to be determined. Improving the conductivity of the films will be also important. One possibility to improve the conductivity is the introduction of gold nanoparticles onto the surface. The change of the type of POM (size, charge, redox potential, etc.) will be also scrutinized.

Scheme 1 .

 1 Scheme 1. Structures of the investigated poly-ZnOEP polymers featuring viologen or bis-viologen spacers and a K12.5Na1.5[NaP5W30O110] Preyssler-type polyoxometalate.

Fig. 1 .

 1 Fig. 1. Fixed potential deposition (+1.90 V vs. SCE) and electrochemical quartz crystal microbalance measurements during the electropolymerization of 0.25 mmol.L -1 of A) 4,4'-bpy and B) bpy + -CH2-CH2-CH2-+ bpy 2PF6 -with 0.25 mmol.L -1 ZnOEP in CH3CN/1,2-C2H4Cl2 (1/4) in the presence of 0.1 mol L -1 TBAPF6. Working electrode: ITO (A = 0.2 cm 2 ) deposited on a 9.08 MHz AT-cut quartz crystal.

  19a

Fig. 2 .

 2 Fig. 2. UV-Vis normalized absorption spectrum of A) poly-ZnOEP1 (obtained after 25 iterative scans between -0.9 V and 2.0 V, v = 0.2 V.s -1 ) and of B) poly-ZnOEP2 (obtained after 25 iterative scans between -1.3 V and +2.0 V, v = 0.2 V.s -1 ) onto ITO electrode (red line) or in DMF solution (blue line) compared to ZnOEP (black line) in DMF.

  Figure 3) leads to comparable curves. A plot of the absorbance at λ = 433 nm and λ = 426 nm (Soret band of poly-ZnOEP1 and of poly-ZnOEP2 respectively) as a function of the deposition time (inset of Figure 3AB) shows a nearly linear increase of the absorbance of the film (i.e. the thickness) versus the time of deposition reaching one plateau for time upper than 120 seconds.

Fig. 3 .

 3 Fig. 3. UV-vis absorption spectra of A) poly-ZnOEP1 and B) poly-ZnOEP2 obtained after different deposition time under +1.90 V vs. SCE. Inset: a plot of the absorbance at λ = 433 nm and λ = 426 nm (Soret band of poly-ZnOEP1 and poly-ZnOEP2) as a function of the time of deposition.

Fig. 4 .

 4 Fig. 4. Cyclic voltammograms of A) poly-ZnOEP1 and B) poly-ZnOEP2 film obtained after applied potential of +1.90 V vs. SCE during 180 s. in CH3CN and 0.1 mol.L -1 TBAPF6. WE: ITO. S = 1 cm 2 . v = 0.1 V.s -1 . * reduction of the intermediate isoporphyrin.

a

  Potentials in V vs. SCE were obtained from cyclic voltammetry in 1,2-C2H4Cl2/CH3CN (4/1) containing 0.1 mol L -1 NBu4PF6. Scan rate = 20 mV s -1 . b Potentials in V vs. SCE were obtained from cyclic voltammetry in acetonitrile containing 0.1 mol L -1 NBu4PF6. Scan rate = 20 mV s -1 . c Potentials in V vs. SCE were obtained from cyclic voltammetry in acetonitrile containing 0.1 mol L -1 NaI. Scan rate = 20 mV.s -1 . d Potentials in V vs. SCE were obtained from cyclic voltammetry in H2O containing 0.1 mol L -1 NaI. Scan rate = 20 mV.s -1 . e Potentials in V vs. SCE were obtained from cyclic voltammetry in H2O containing 0.1 M NEt4PF6. Scan rate = 20 mV s -1 . f Working electrode: glass carbon electrode. g Working electrode: ITO, S=1 cm 2 . The given half-wave potentials are equal to E1/2 = (Epa + Epc)/2. Under bracket: △Ep = |Epa-Epc| in mV. h only the cathodic peak is detected.

Fig. 5 .

 5 Fig. 5. A) thickness measurement, B) tapping mode AFM topography maps recorded with poly-ZnOEP2 (deposition on +1.90 V vs. SCE, 180 seconds) and C) section analysis of the aggregate marked by a blue line.

Fig. 6 .

 6 Fig. 6. XPS of poly-ZnOEP1 films on ITO with and without P5W30. Global XPS spectra (A), C 1s (B), N 1s (C), O 1s (D), P 2p3 (E), Zn 2p3 (F), Na 1s (G), W 4f7 (H), F 1s (I).

  obtained in a 0.1 mol L -1 solution of TBAPF6in 1,2-C2H4Cl2/CH3CN (4/1) containing 2.5 × 10 -4mol.L -1 of ZnOEP and 2.5×10 -4 mol.L -1 of 4,4'-bpy (poly-ZnOEP1) or bpy + -CH2-CH2-CH2-+ bpy•2PF6 -(poly-ZnOEP2) under an argon atmosphere. Electropolymerization is carried out at a fixed potential +1.90 V vs. SCE for 180 seconds.

Fig. 7 .

 7 Fig. 7. UV-vis spectra of the modified ITO electrode with A) poly-ZnOEP1 and B) poly-ZnOEP2 after soaking in 0.1 mmol.L -1 K12.5Na1.5[NaP5W30O110] aqueous solution for 10 min, 15 min, 30 min,

Fig. 8 .

 8 Fig. 8. Frequency response of QCM sensor to K12.5Na1.5[NaP5W30O110] adsorption onto the poly-ZnOEP1 film (deposited onto a 9.08 MHz AT-cut quartz resonator with a thin ITO layer (A = 0.2 cm 2 )). The start base line was obtained when the sensor was exposed to H2O. The arrows ↓ indicated the injection of K12.5Na1.5[NaP5W30O110] (c = 0.1 mmol.L -1 ). The arrow ↑ indicated the washing using H2O. B) Mass change (Δm) calculated from Sauerbrey's equation versus the soaking time. Δf1, Δf2, and Δf3 are measured each time after 60 minutes (variation of frequency induced by [NaP5W30O110] 14- /PF6 -exchange in the film during each 60 minutes soaking cycle in the K12.5Na1.5[NaP5W30O110]

Fig. 9 .

 9 Fig. 9. CVs of poly-ZnOEP1 (black line) and poly-ZnOEP1/P5W30 (red line) films on ITO in A) acetonitrile and B) H2O containing 0.5 mol.L -1 NaI. S = 1 cm 2 . v = 20 mV s -1 . (→) shows the scan direction.

  ZnOEP/P5W30. XPS analyses have been carried out to confirm the presence of the [NaP5W30O110] 14-polyoxometalate on the surface of the films. The presence of Na 1s (1073.4 eV, Fig. 6, red curve) and W 4f7 (36.4 eV for W4f7/2 and 37.8 eV for W4f5/2, Fig. 6H, red curve) peaks, the much lower intensity of F 1s (686.8 eV, Fig. 6I, red curve), together with the signal of O 1s (531.6 eV, Fig. 6D, red curve) and P 2p3 (133.3 eV, Fig. 6E, red curve) arising from the P-O bonds in POM species further support the conclusion that [NaP5W30O110] 14-species are adsorbed on the poly-ZnOEP1 film to yield poly-ZnOEP1/P5W30. XPS data collected with poly-ZnOEP2 and poly-ZnOEP2/P5W30 (Fig. S4) are analogous to those recorded with poly-ZnOEP1 and poly-ZnOEP1/P5W30. The P 2p line at binding energy of 136.6 eV for poly-ZnOEP1 (136.7 eV for poly-ZnOEP2) as well as the F 1s line at 686 eV are attributed to the PF6 - counteranions 22 while the signal of P 2p at 133.3 eV corresponds to the binding energy of the five phosphorus atoms in [NaP5W30O110] 14-. It confirms the exchange of PF6 -by [NaP5W30O110] 14-. Similar behaviors have been observed for poly-ZnOEP2 and poly-ZnOEP2/P5W30.

Fig. 10 .

 10 Fig. 10. Tapping mode AFM topography of A) and B) poly-ZnOEP1/P5W30 and C) and D) poly-ZnOEP2/P5W30 hybrid films and section analysis of the aggregate marked by a blue lines.

  Figures 11-12 and Figures S14-S15 show the photocurrent response of poly-ZnOEP1/P5W30 and poly-ZnOEP2/P5W30 hybrid films respectively obtained under Xe irradiation (λ > 385 nm) by soaking in a K12.5Na1.5[NaP5W30O110]

  photocurrent was found to be 3.4 times larger for poly-ZnOEP1/P5W30 (60 min. soaking in P5W30 solution) than for poly-ZnOEP1 and 1.3 times larger for poly-ZnOEP2/P5W30 (30 min. soaking in P5W30 solution) than for poly-ZnOEP2. The comparison is done using the soaking time giving the maximum of magnitude of the photocurrent (60 minutes for poly-ZnOEP1/P5W30 versus 30 minutes.for poly-ZnOEP2/P5W30, Fig.12, Fig.S14and Fig.S15). The corresponding photocurrent measured were 31.89 for poly-ZnOEP1/P5W30 and 24.90 A/cm 2 for poly-ZnOEP2/P5W30. The incorporation of POMs also leads to an improvement of the photovoltage up to -28 mV and -105 mV for poly-ZnOEP1/P5W30 and poly-ZnOEP2/P5W30, respectively.

Fig. 11 .

 11 Fig. 11. Photoelectrochemical response of poly-ZnOEP1 (black line) and poly-ZnOEP1/P5W30 (red line) (soaking time in P5W30 solution with 60 min) A) in acetonitrile and B) in H2O under on-off light illumination from a 300 W Xe arc lamp (with λ > 385 nm long pass filter) in containing I3 -5 mmol.L - 1 and I -0.5 mol.L -1 . BIAS potential: 0.00 V vs. OCP.

Fig. 12 .

 12 Fig. 12. Photoelectrochemical response of A) poly-ZnOEP1/P5W30 and poly-ZnOEP2/P5W30 with different soaking time in K12.5Na1.5[NaP5W30O110] solution under on-off light illumination from a 300 W Xe arc lamp (with λ > 385 nm long pass filter) in acetonitrile (black line) and H2O (red line) containing I3 -5 mmol.L -1 and I -0.5 mol.L -1 . BIAS potential: 0.00 V vs. OCP.

Fig. 13 .

 13 Fig. 13. Electrochemical impedance spectroscopy (EIS) for poly-ZnOEP1/P5W30 (soaking time in P5W30 solution with 60 min) in A) in acetonitrile and B) in H2O with and without illumination from a 300 W Xe arc lamp (with λ > 385 nm long pass filter) containing I3 -5 mmol.L -1 and I -0.5 mol.L -1

  -4.71 eV and -5.01 eV in CH3CN and H2O containing 0.5 mol L -1 I -, respectively. The level of the excited state (couple P +• /P * ) and the ground state (couple P +• /P) are -3.92 eV and -5.92 eV for poly-ZnOEP1/P5W30, and -3.90 eV and -5.94 eV for poly-ZnOEP2/P5W30, respectively. The energy level of the eV (-0.42 V vs. NHE) and -4.41 eV (-0.09 V vs. NHE) in CH3CN and H2O containing 0.5 mol L -1 I -, respectively. The energy level of V 2+ /V +• in poly-ZnOEP1/P5W30 were -4.41 eV (-0.09 V vs. NHE) and -4.48 eV (-0.02 V vs. NHE) in CH3CN and H2O containing 0.5 mol L -1 I -, respectively. The energy level of I3 -/I -were -4.70 eV and -5.06 eV respectively, in CH3CN and H2O containing 0.5 mol L -1 I -on the absolute scale.In contrast, the cathodic photo-electric conversion mechanism of poly-ZnOEP1/P5W30 and poly-ZnOEP2/P5W30 film observed in aqueous solution could be explained by the following processes:(1) the band-gap excitation from HOMO to LUMO of the ZnOEP macrocycle under illumination, (2) electron transfer from the LUMO of ZnOEP to P5W30,(3) the reduced P5W30 relay electron to viologen (or bis-viologen) dications, (4) viologen (or bis-viologen) cation radicals transfer electrons to I3 -which is reducted into I -, (5) reoxidation of the I -at the Pt counter-electrode, the ZnOEP being regenerated by an electron transfer from the ITO (Fig.14).

Fig. 14 .

 14 Fig. 14. Schematic illustration of the energy level diagram showing electron transfer processes of poly-ZnOEP1/P5W30 in A) in acetonitrile and B) in H2O containing I3 -5 mmol.L -1 and I -0.5 mol.L -1 . (V = viologen, P = porphyrin).

Table 1

 1

	UV-visible spectral data for ZnOEP, 4,4'-bpy and bpy + -CH2-CH2-CH2-+ bpy 2PF6 -in
	acetonitrile, poly-ZnOEP1/P5W30 and poly-ZnOEP2/P5W30 on ITO. Under bracket: molar
	extinction coefficient (ε /10 3 L.M.cm -1 ).
	Compound	Soret band/nm	Q bands/nm π-π * Band/nm
	ZnOEP	404 (414.2)	533 (187.1),
			568 (199.8)
	4,4'-bpy		285 (13.4)
	bpy + (CH2)3bpy + 2PF6 -		266 (40.8)
	poly-ZnOEP1	431	612
	poly-ZnOEP2	433	611, 709
	poly-ZnOEP1/P5W30	435	616
	poly-ZnOEP2/P5W30	434	608

Table 2 ,

 2 Fig 4A and Fig. S2A).

		0.12							0.10
		0.10							0.08
	Absorbance	0.04 0.06 0.08					5 s 10 s 15 s 30 s 45 s	Absorbance	0.04 0.06					5s 20s 40s 60s
		0.02					60 s 120 s 180 s		0.02					90s 120s 180s
									0.00
		0.00
		300	400	500	600	700	800	900	300	400	500	nm 600	700	800

Table 3 .

 3 Fitting results for the EIS measurements performed in CH3CN or H2O.

		ZnOEP1	ZnOEP1	ZnOEP1/P5W30	ZnOEP1/P5W30
			dark	light		dark		light
	Solvent	CH3CN H2O CH3CN H2O CH3CN	H2O	CH3CN H2O
	RITO/Film / Ω	429	103140	395	48705	356	134459	297	19501
	CITO/Film /µF	11	11	11	11	13	11	13	14
	Rct_film / Ω	1440	1071	1072	1534	1186	866	778	5504
	Cfilm /µF	106	199	107	119	113	247	127	317

Acknowledgements

We thank CNRS, the Université de Strasbourg (France), Université Paris-Descartes (Paris, France), Université Pierre et Marie Curie (Paris, France), ICSN, ECE Paris Ecole d'Ingénieurs (France), and Fudan University (Shanghai, China) for funding of this work. LR also thank the Université de Strasbourg for the projet "Idex Attractivité 2012" which has also supported one part of this research, as well as the Oversea Study Program of Guangzhou Elite Project (GEP) for the PhD. grant of Zhaohui Huo. This work was also supported by Fund of senior visiting professor of Fudan University.

CB and ESA wish to thank the "Agence National de la Recherche" (ANR-12-BS07-0014-01) and the ARCANE Labex (ANR-11-LABX-0003-01) for financial support.

Appendix A. Supplementary data

Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/.........

Photovoltaic properties of supramolecular assemblies obtained by incorporation of


M Nguyen

C Choquet

Pierre Sicard

F Kober

I Varlet

P Rihet

Sylvain Richard

C Nguyen

Monique Bernard

R Kelly

22 -Temporal deletions of Nkx2-5 induce hypertrabeculation and progressive conduction defects and heart failure

à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Nguyen M, Choquet C, Sicard P, Kober F, Varlet I, Rihet P, Richard S, Nguyen C, Bernard M, Kelly R, Lalevée N, Miquerol L.

122 -Temporal deletions of Nkx2-5 induce hypertrabeculation and progressive conduction defects and heart failure.

In: Archives of Cardiovascular Diseases Supplements. Vol. 9. Printemps de la Cardiologie : Recherche Fondamentale et Clinique, Nantes, 6-7 April. ;2017. p. 208. doi: 10.1016/S1878-6480(17) 30515-3. Left ventricular non-compaction (LVNC), characterized by hypertrabeculation and deep trabecular recesses in the left ventricle, is the most common cardiomyopathy with a spectrum ranging from extreme normal variants to a pathological phenotype. In all forms, heart failure and sudden cardiac death represent the most severe complications related with non-compaction and arrhythmias. Defects in ventricular compaction and conduction are traits observed in patients and mutant mice carrying mutations in NKX2-5, encoding a key transcriptional regulator of cardiac development. In order to dissect the role of this gene in the apparition of the pathological outcomes of LVNC, we established a LVNC mouse model by inactivating Nkx2-5 in a time and tissue specific manner. Nkx2-5 was conditionally knockout in atria and trabecular cardiomyocytes at embryonic stages, when trabeculae arise, or during fetal stage, when they start to compact, or at neonatal stages, when the ventricles are mature. Our results show that the loss of Nkx2-5 at embryonic stages provokes a hypertrabeculation associated with important subendocardial fibrosis and Purkinje fibers hypoplasia in adult mice. These phenotypes are milder when the deletion occurred at fetal stages. Deletion only in the ventricular conduction system, at neonatal stage, leads to a progressive hypoplasia of this tissue without signs of hypertrabeculation nor fibrosis. However, all these mice develop progressively conduction defects and heart failure. The analysis of molecular pathways associated to these phenotypes, demonstrated that Nkx2-5 plays pleiotropic roles during trabecular development. Thus, deletion of Nkx2-5 during trabecular development represents a good model for studying the cellular and molecular mechanisms associated with LVNC, and the more pronounced disorder is provoked by a deletion at earlier stages.


Natacha Fourny

Carole Lan

Frank Kober

Monique Bernard

Martine Desrois

Modification of cardiac morphology was associated with impaired myocardial sensitivity to ischemia-reperfusion injury in a diet-induced metabolic syndrome model

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Fourny N, Lan C, Kober F, Bernard M, Desrois M. Modification of cardiac morphology was associated with impaired myocardial sensitivity to ischemia-reperfusion injury in a diet-induced metabolic syndrome model.

In: Diabetologia. Vol. 60 Supplement 1. 53rd Annual Meeting of the European Association for the Study of Diabetes (EASD), Lisbon/PT, September 11-15. ; 2017. pp. S547-S547. doi: 10.1007/s00125-017-4350-z.

Background and aims: Metabolic Syndrome (MetS) is defined by multiple risk factors that predict type 2 diabetes and cardiovascular complications, such as myocardial infarction, especially in women. Consequently the aim of this study was to investigate in vivo and ex vivo the effects of a high-fat-high-sucrose diet (HFHSD) on the development of metabolic syndrome (MetS), cardiac morphology and sensitivity to ischemia-reperfusion injury of female Wistar rat.

Materials and methods: Female Wistar rats, subjected to HFHSD (FHFD) or Normal Diet (FND) during 5 months, were explored in vivo every month with multimodal cardiovascular magnetic resonance (CMR). Cine-MRI (Magnetic Resonance Imaging) and arterial spin labeling (ASL-FAIR) techniques were used to determine cardiac morphology, function and perfusion. Triglyceride (TG) content in heart and liver 1was also evaluated with H Magnetic Resonance Spectroscopy (MRS). 1Sub-cutaneous and visceral adipose tissues were measured with H MRI. Then, rats underwent an intraperitoneal glucose tolerance test (IPGTT) to determine glycemic status. Finally, isolated heart were perfused with a physiological buffer containing 0.4 mM palmitate for 24 minutes before switching to 1.2 mM palmitate during 32 minutes low-flow (0.5 mL/min/g wet wt) ischemia. Next, flow was restored with 0.4 mM palmitate buffer for 32 minutes. High-energy phosphates and intracellular pH were measured during the experimental course by P magnetic resonance spectroscopy with simultaneous measurement of contractile function. Coronary flow was measured before and after ischemia. At the end of experiments, hearts were freeze-clamped for biochemical assays.

Results: In FHFD vs. FND, CMR showed an increase of systolic wall thickness over time (p<0.05) and diastolic wall thickness at 3 and 5 months 1(p<0.01); H MRS showed that hepatic TG content was increased (p<0.01) at 5 month but myocardial TG content was not different. IPGTT showed a significant glucose intolerance (p<0.001) and plasma free fatty acids were increased (p<0.05) in FHFD vs. FND. At 5 months, weight was not different between groups but FHFD exhibited an abdominal obesity with increased visceral adipose tissue (p<0.05), % fat (p<0.05) and % visceral fat (p<0.05) compared with FND. Ex vivo myocardial function was impaired in FHFD vs. FND before (p<0.01) and after ischemia (p<0.05).

Conclusion: HFHSD-induced MetS was characterized by glucose intolerance, abdominal obesity, hepatic fat deposit which were associated with modification of cardiac morphology and higher myocardial sensitivity to ischemiareperfusion injury. These results may be related to higher risk of cardiovascular complications among type 2 diabetic obese women. Supported by: Aix-Marseille Univ, CNRS, France Life Imaging Disclosure: N. Fourny: None.