Elvin V Salerno

Albano N Carneiro Neto

Svetlana V Eliseeva
email: s.v.eliseeva@cnrs-orleans.fr

Miguel A Hernández- Rodríguez

Jacob C Lutter

Timothée Lathion

Jeff W Kampf

Stéphane Petoud
email: stephane.petoud@inserm.fr

Luis D Carlos
email: l.d.carlos@ua.pt

Vincent L Pecoraro
email: v.l.pecoraro@umich.edu.

The effect of ligands' energy levels on thermal dependence of lanthanide emission was examined to create new molecular nanothermometers. A series of Ln2Ga8L'8L"4 metallacrowns (shorthand Ln2L'8), where Ln = Gd 3+ , Tb 3+ , or Sm 3+ ; H3L' = salicylhydroxamic acid (H3shi), 5-methylsalicylhydroxamic acid (H3mshi), 5methoxysalicylhydroxamic acid (H3moshi), and 3-hydroxy-2-naphthohydroxamic acid (H3nha); and H2L" = isophthalic acid (H2iph) was synthesized and characterized. Within the series, ligand-centered singlet state (S1) energy levels ranged from 23300 to 27800 cm -1 , while triplet (T1) energy levels ranged from 18150 to 21980 cm -1 . We demonstrated that the difference between T1 levels and relevant energies of the excited 4 G5/2 level of Sm 3+ (17800 cm -1 ) and 5 D4 level of Tb 3+ (20400 cm -1 ) is the major parameter controlling thermal dependence of the emission intensity via the back energy transfer mechanism. However, when the energy difference between S1 and T1 levels is small (below 3760 cm -1 ), the S1→T1 intersystem crossing (and its reverse, S1←T1) mechanism contributes to the thermal behavior of metallacrowns. Both mechanisms affect Ln 3+ -centered room-temperature quantum yields with values ranging from 2.07(6) to 31.2(2) % for Tb2L'8 and from 0.0267(7) to 2.27(5) % for Sm2L'8. The maximal thermal dependence varies over a wide thermal range (ca. 150-350 K), based on energy gaps between relevant ligand-based and lanthanide-based electronic states. By mixing Tb2moshi'8 with Sm2moshi'8 in a 1:1 ratio an optical thermometer with a relative thermal sensitivity larger than 3 %/K at 225 K was created. Other temperature ranges are also accessible with this approach.

Understanding thermal dynamics is essential for the analysis and engineering of almost any physical system. Temperature has long been an important scientific measurement, with established thermometry techniques such as mercury-based pressure gauges or voltage-based thermocouples. [START_REF] Grodzinsky | History of the Thermometer[END_REF] Optical thermometers are gaining an increasing interest as they provide a unique means for the noncontact detection of the temperature of a target. For example, pyrometry-based methods analyze the properties of the emitted infrared radiation from a system to determine thermal parameters, with applications such as infrared temperature guns or determination of the temperature of distant stars. [START_REF] Araújo | Multi-Spectral Pyrometry-a Review[END_REF][START_REF] Ni | Polarization Pyrometry: An Improvement to Multi-Wavelength Optical Pyrometry[END_REF] Optical thermometry methods are often the basis for the up-and-coming generation of thermometers known as nanothermometers. [START_REF] Quintanilla | Guiding Rules for Selecting a Nanothermometer[END_REF] Nanothermometry is the measurement of temperature at the submicron level. As we seek to understand the physical basis of many systems from the ground up, nanothermometry becomes increasingly important. This field has a plethora of uses such as the analysis of microelectronics, [START_REF] Brites | Organic-Inorganic Eu3+/Tb3+ Codoped Hybrid Films for Temperature Mapping in Integrated Circuits[END_REF] cellular biology, [START_REF] Okabe | Intracellular Thermometry Uncovers Spontaneous Thermogenesis and Associated Thermal Signaling[END_REF] nanomedicine, [START_REF] Piñol | Real-Time Intracellular Temperature Imaging Using Lanthanide-Bearing Polymeric Micelles[END_REF][START_REF] Ximendes | Infrared-Emitting Multimodal Nanostructures for Controlled In Vivo Magnetic Hyperthermia[END_REF] or microfluidics [START_REF] Graham | Quantitative Mapping of Aqueous Microfluidic Temperature with Sub-Degree Resolution Using Fluorescence Lifetime Imaging Microscopy[END_REF] for which traditional methods of thermometry are not amenable.

An optical nanothermometer correlates a temperature value with the change in photophysical properties of a probe. Two schemes used involve observing changes in luminescence lifetimes or emission intensities in response to temperature. Lifetime-based techniques are functional and can be quite sensitive, but rely on specialized equipment, rigorous data analysis methodologies, have long acquisition times that preclude dynamic measurements shorter than the lifetime of the probe, and are ineffective for short-timescale thermal mapping. [START_REF] Brites | Lanthanides in Luminescent Thermometry[END_REF] Ratiometric intensity-based measurements are another promising approach. This technique correlates the temperature with the ratio between the integrated intensities of two different emission bands, Δ. [START_REF] Brites | Lanthanide-Based Thermometers: At the Cutting-Edge of Luminescence Thermometry[END_REF] A ratiometric approach, rather than the intensity measurement of a single transition, is necessary to avoid artifacts coming from parameters besides temperature such as probe concentration or signal attenuation. Ratiometric probes can be based on a single compound, [START_REF] Vetrone | Temperature Sensing Using Fluorescent Nanothermometers[END_REF][START_REF] Morinvil | Advancing Neodymium Single-Band Nanothermometry[END_REF][START_REF] Hernández-Rodríguez | Comparison of the Sensitivity as Optical Temperature Sensor of Nano-Perovskite Doped with Nd3+ Ions in the First and Second Biological Windows[END_REF] or on a combination of two compounds. [START_REF] Brites | Lanthanides in Luminescent Thermometry[END_REF][START_REF] Quintanilla | Luminescent Nanothermometry with Lanthanide-Doped Nanoparticles[END_REF] Solid-state and molecular materials can be used to create nanothermometric devices. Some prominent probes include nitrogen-vacancy nanodiamonds, [START_REF] Kucsko | Nanometre-Scale Thermometry in a Living Cell[END_REF][START_REF] Neumann | High-Precision Nanoscale Temperature Sensing Using Single Defects in Diamond[END_REF] organic fluorophores, [START_REF] Uchiyama | Luminescent Molecular Thermometers for the Ratiometric Sensing Intracellular Temperature[END_REF][START_REF] Arai | Mitochondria-Targeted Fluorescent Thermometer Monitors Intracellular Temperature Gradient[END_REF] metal-organic frameworks [START_REF] Wang | A Eu/Tb-Mixed MOF for Luminescent High-Temperature Sensing[END_REF][START_REF] Rocha | Lanthanide Organic Framework Luminescent Thermometers[END_REF] , metal-coordinating molecules, [START_REF] Bao | A Stoichiometric Terbium-Europium Dyad Molecular Thermometer: Energy Transfer Properties[END_REF][START_REF] Errulat | A Luminescent Thermometer Exhibiting Slow Relaxation of the Magnetization: Toward Self-Monitored Building Blocks for Next-Generation Optomagnetic Devices[END_REF] or nanoparticles. [START_REF] Brites | A Luminescent Molecular Thermometer for Long-Term Absolute Temperature Measurements at the Nanoscale[END_REF][START_REF] Freddi | A Molecular Thermometer for Nanoparticles for Optical Hyperthermia[END_REF] Lanthanide(III)-based thermometry probes have inherently attractive properties due to the buried nature of 4f valence orbitals. In particular, properties including: (i) longlived emission lifetimes which can be used to dodge background fluorescence via time-gated experiments, [START_REF] Johansson | Time Gating Improves Sensitivity in Energy Transfer Assays with Terbium Chelate/Dark Quencher Oligonucleotide Probes[END_REF] and (ii) sharp emission bands with fixed (or minimally affected) positions of the barycenters that can be easily distinguished from background fluorescence. [START_REF] Bünzli | Taking Advantage of Luminescent Lanthanide Ions[END_REF] In solid-state systems such as in metal-organic frameworks or in lanthanidedoped nanoparticles, the change in emission intensities is often induced by thermally-dependent energy transfer between two different lanthanide(III) ions (Ln 3+ ). [START_REF] Neto | Rationalizing the Thermal Response of Dual-Center Molecular Thermometers: The Example of an Eu/Tb Coordination Complex[END_REF] Many sensitive nanothermometric systems that benefit from this principle have been created. [START_REF] Brites | Lanthanide-Based Thermometers: At the Cutting-Edge of Luminescence Thermometry[END_REF][START_REF] Wang | A Eu/Tb-Mixed MOF for Luminescent High-Temperature Sensing[END_REF][START_REF] Rocha | Lanthanide Organic Framework Luminescent Thermometers[END_REF][START_REF] Trannoy | Engineering of Mixed Eu 3+ /Tb 3+ Metal-Organic Frameworks Luminescent Thermometers with Tunable Sensitivity[END_REF][START_REF] Wang | Lanthanide-Organic Framework Nanothermometers Prepared by Spray-Drying[END_REF][START_REF] Ren | A Cryogenic Luminescent Ratiometric Thermometer Based on a Lanthanide Phosphonate Dimer[END_REF][START_REF] Zhao | A Highly Sensitive Near-Infrared Luminescent Metal-Organic Framework Thermometer in the Physiological Range[END_REF][START_REF] Xia | A Eu and Tb Co-Doped MOF-5 Compound for Ratiometric High Temperature Sensing[END_REF][START_REF] Vries | Multimetal Rare Earth MOFs for Lighting and Thermometry: Tailoring Color and Optimal Temperature Range through Enhanced Disulfobenzoic Triplet Phosphorescence[END_REF][START_REF] Cui | A Ratiometric and Colorimetric Luminescent Thermometer over a Wide Temperature Range Based on a Lanthanide Coordination Polymer[END_REF] However, their design requires a close proximity between the Ln 3+ to ensure energy transfer. Moreover, the modulation of functional properties of solid-state systems might be challenging and restricted by the limited choice of available methodologies.

Molecular nanothermometers are desirable because of their functional properties, for example, their sensitivity and thermal response range, [START_REF] Gálico | Triplet-State Position and Crystal-Field Tuning in Opto-Magnetic Lanthanide Complexes: Two Sides of the Same Coin[END_REF] biocompatibility [START_REF] Lee | Designing Dendrimers for Biological Applications[END_REF][START_REF] Martinić | One Approach for Two: Toward the Creation of Near-Infrared Imaging Agents and Rapid Screening of Lanthanide(III) Ion Sensitizers Using Polystyrene Nanobeads[END_REF] and surface binding, [START_REF] Karakoti | Surface Functionalization of Quantum Dots for Biological Applications[END_REF] can be tuned by chemical modifications.

Molecular thermometers are typically either allorganic fluorophores or metal-coordinating complexes. Organic fluorophores have drawbacks such as broad emissive bands with short luminescence lifetimes that cannot always be differentiated from background fluorescence, particularly in biological thermal imaging applications where autofluorescence contribution is significant. In metal-coordinating organic complexes, coordinated metals are usually d-transition metal ions, such as Cu 2+ , [START_REF] Cauzzi | Temperature-Dependent Fluorescence of Cu 5 Metal Clusters: A Molecular Thermometer[END_REF][START_REF] Shamsieva | Fresh Look on the Nature of Dual-Band Emission of Octahedral Copper-Iodide Clusters-Promising Ratiometric Luminescent Thermometers[END_REF][START_REF] Li | Photoluminescent Phosphinine Cu(I) Halide Complexes: Temperature Dependence of the Photophysical Properties and Applications as a Molecular Thermometer[END_REF] or Ln 3+ ions. [START_REF] Brites | Organic-Inorganic Eu3+/Tb3+ Codoped Hybrid Films for Temperature Mapping in Integrated Circuits[END_REF][START_REF] Bao | A Stoichiometric Terbium-Europium Dyad Molecular Thermometer: Energy Transfer Properties[END_REF][START_REF] Ren | A Cryogenic Luminescent Ratiometric Thermometer Based on a Lanthanide Phosphonate Dimer[END_REF] There are promising d-transition metal systems, but these can suffer from limitations similar to the ones of organic fluorophores where their response is not tunable for use across a wide-range of temperatures.

Ln 3+ -based molecular complexes offer the abovementioned benefits such as sharp emission bands and long luminescence lifetimes. However, free Ln 3+ suffer from very weak absorbance due to the parityforbidden nature of most f-f transitions. [START_REF] Bünzli | Basics of Lanthanide Photophysics[END_REF] This weak absorptivity of Ln 3+ ions can be overcome by a sensitization through an appropriate ligand via the "antennae effect". [START_REF] Uha | Novel Antennae for the Sensitization of near Infrared Luminescent Lanthanide Cations[END_REF] Studies have shown that the energy positions of the excited singlet (S1) and triplet (T1) states of the ligand relative to the accepting energy level of the Ln 3+ level play an important role in the sensitization of Ln 3+ in such compounds, [START_REF] Deiters | Luminescent Bimetallic Lanthanide Bioprobes for Cellular Imaging with Excitation in the Visible-Light Range[END_REF][START_REF] Gassner | Remarkable Tuning of the Photophysical Properties of Bifunctional Lanthanide Tris(Dipicolinates) and Its Consequence on the Design of Bioprobes[END_REF][START_REF] Chauvin | A Versatile Ditopic Ligand System for Sensitizing the Luminescence of Bimetallic Lanthanide Bio-Imaging Probes[END_REF][START_REF] Latva | Correlation between the Lowest Triplet State Energy Level of the Ligand and Lanthanide(III) Luminescence Quantum Yield[END_REF][START_REF] Archer | Characterization, and Luminescence of Europium(III) Schiff Base Complexes[END_REF] and can play a role in thermal dependence of emission intensity. [START_REF] Katagiri | Energy-Transfer Mechanism in Photoluminescent Terbium(III) Complexes Causing Their Temperature-Dependence[END_REF][START_REF] Katagiri | Thermo-Sensitive Luminescence Based on the Back Energy Transfer in Terbium(III) Complexes[END_REF] Ideally, the electronic states of the ligand should be higher in energy than, and close enough to, the accepting Ln 3+ energy state to permit adequate energy transfer, but not too close to prevent a back energy transfer from the Ln 3+ to the ligand. The thermal response of Ln 3+ emission can also be tuned via interaction with the ligand field to increase the thermal sensitivity [START_REF] Brites | Tuning the Sensitivity of Ln3+-Based Luminescent Molecular Thermometers through Ligand Design[END_REF] or to change the range of thermal activity. [START_REF] Gálico | Triplet-State Position and Crystal-Field Tuning in Opto-Magnetic Lanthanide Complexes: Two Sides of the Same Coin[END_REF] Some sensitive Ln 3+ -based thermometers have been constructed, but a strategy for rational tuning of a high sensitivity Ln 3+ -based molecular system for use across a wide range of temperatures is currently missing. Color code: Ga, pink; Ln, green; O, red; N, blue; C, grey. Solvents, counter cations, and hydrogen atoms are omitted for clarity. This structure was obtained on Xray single crystal diffraction on the Sm 3+ analogue.

Herein we present a series of molecular nanothermometers based on dimeric metallacrowns (MCs) with the general composition Ln2Ga8L'8L"4 (shorthand Ln2L '8), where Ln 3+ = Gd 3+ , Tb 3+ , or Sm 3+ ; H3L' = salicylhydroxamic acid (H3shi), 5methylsalicylhydroxamic acid (H3mshi), 5methoxysalicylhydroxamic acid (H3moshi), and 3hydroxy-2-naphthohydroxamic acid (H3nha); and H2L" = isophthalic acid (H2iph) (Figure 1, center, right). Within the studied series of the Ln2L'8, the MC dimeric structures have similar topology (Figure 1; Figure 2, left), ensuring the similarity of the first coordination sphere around the Ln 3+ ion. For the Tb2L'8 and Sm2L'8 MCs, photophysical properties were investigated in detail. Diffuse reflectance and Ln 3+centered excitation spectra, luminescence lifetimes, quantum yields, as well as thermal dependence of emission spectra from ca. 11 to 400 K were acquired and analyzed. We have also studied the ligandcentered properties of the corresponding Gd2L'8 MCs to determine the energy positions of S1 and T1 levels. To assemble the Ln2L'8, MCs we have chosen sensitizing hydroxamate ligands that possess disparate S1 and T1 energy levels. In this manner, we have analyzed how the Ln*-T1 and Ln*-S1 energy gaps influence the thermal dependence of emission intensities. We rationalize these findings in a broader sense to describe how one can change the excited state energies of organic antennae to modify the range of the highest thermal sensitivity (ca. 11-400 K). The reported findings can also be relevant for further designs of Ln 3+ -based molecular compounds with large quantum yields, because quantum yields can be directly dependent on Ln 3+ -ligand back energy transfer.

Synthesis

General synthetic considerations. All reagents and chemicals were purchased from commercial sources and used without further purification. All reactions were carried out aerobically under ambient conditions. Elemental analyses were performed by Atlantic Microlabs Inc. ESI-MS spectra were collected with an Agilent 6230 TOF HPLC-MS mass spectrometer in negative ion mode (-350V) on samples dissolved in methanol at a concentration of 2 mg/mL. [START_REF] Grodzinsky | History of the Thermometer[END_REF] H NMR spectra were collected on a Varian MR400 NMR in deuterated DMSO at a concentration of 4 mg/mL.

Ln2shi8

complexes and N,3-dihydroxy-2naphthamide (H3nha) were prepared according to the previously reported procedures. [START_REF] Nguyen | One-Step Assembly of Visible and Near-Infrared Emitting Metallacrown Dimers Using a Bifunctional Linker[END_REF][START_REF] Jiang | A Mononuclear Dysprosium(Iii) Single-Molecule Magnet with a Non-Planar Metallacrown[END_REF] Preparation of 5-methoxy salicylhydroxamic acid (H3moshi). Potassium hydroxide (47.5 mmol) and hydroxylamine monohydrochloride (40 mmol) were combined in 20 mL of methanol and stirred for ten minutes over ice. A white precipitate (potassium chloride salt) formed. The precipitate was removed via vacuum filtration yielding a clear and colorless solution of hydroxylamine in methanol. To this stirred solution was added liquid methyl-5-methoxy salicylate (5 mmol). The solution immediately turned yellow. The solution was stirred for more than four days with a cap to prevent solvent loss. After four days, a clear orange solution was present. The pH was adjusted to ~1 with 2M aqueous HCl. Then 30 mL of water was added to precipitate a pale, orange solid. This solid was collected via vacuum filtration and washed with cold water. The clear/yellow filtrate was discarded. The solid was then triturated in methylene chloride, then collected via vacuum filtration. The precipitate was dried in vacuo to yield pure solid with 57.9% yield. [START_REF] Grodzinsky | History of the Thermometer[END_REF]

Preparation of 5-methyl salicylhydroxamic acid (H3mshi

). Potassium hydroxide (237.5 mmol) and hydroxylamine monohydrochloride (200 mmol) were combined in 100 mL of methanol and stirred for ten minutes over ice. A white precipitate (potassium chloride salt) formed. The precipitate was removed via vacuum filtration yielding a clear and colorless solution of hydroxylamine in methanol. To this stirred solution was added liquid methyl-5-methyl salicylate (5 mmol). The solution remains (initially) clear and colorless. The solution was stirred for more than seven days with a cap to prevent solvent loss. After seven days, a clear yellow solution was obtained. The pH was adjusted to ~1 with 2M aqueous HCl. Then 200 mL of water was added. The product was extracted with 4x50 mL portions of ethyl acetate. The solvent was removed via rotary evaporation. A small amount of yellow liquid and a pale white solid emerge. The solid was collected via filtration, rinsed with methylene chloride, then dried in vacuo to yield a pure solid with 56.5% yield. [START_REF] Grodzinsky | History of the Thermometer[END_REF] Preparation of Ln2mshi8 complexes. 5-methyl salicylhydroxamic acid (H3mshi) (0.6 mmol), Ln(NO3)3 . xH2O (0.15 mmol) (Ln 3+ = Sm 3+ , Gd 3+ , Tb 3+ ), Ga(NO3)3 . xH2O (0.6 mmol), and isophthalic acid (0.3 mmol) were dissolved in 30 mL of dimethyl formamide. A concentrated aqueous NaOH solution (19.87 M, 2.4 mmol) was added slowly and the resulting solution was stirred for two hours under ambient conditions. The solution was filtered and the filtrate was left for slow evaporation. After about 1 week, an amorphous, powdery precipitate appeared. The mixture was filtered again, and the filtrate was collected and again set for slow evaporation, producing crystalline compound within 2-3 weeks. A crystalline compound was collected via filtration and dried in vacuo. A pale white crystalline solid was collected in each case.

Sm2mshi8:

[Sm2Ga8(mshi)8(iph)4]Na2 Preparation of Ln2nha8 complexes. Ln(NO3)3 . xH2O (0.125 mmol) (Ln 3+ = Sm 3+ , Gd 3+ , Tb 3+ ) and Ga(NO3)3 . xH2O (0.5 mmol) were combined in 5 mL of dimethylformamide yielding to a clear and colorless solution. Separately, N,3-dihydroxy-2-naphthamide (H3nha) (0.5 mmol) and isophthalic acid (0.25 mmol) were dissolved in 15 mL of dimethyl formamide, yielding a clear and yellow solution. To this solution, a concentrated aqueous NaOH solution (2.0 mmol) was added slowly and the solution was stirred for five minutes. Then, the two solutions were combined together and the resulting mixture was stirred for more than two hours under ambient conditions. The solution was filtered and the filtrate was left for slow evaporation, producing crystalline compound within 2-4 weeks. The compound was collected via filtration and dried in vacuo. A brown crystalline solid was collected in each case. Crystallography. Single crystals were grown from a dimethylformamide/water solution of the compounds at room temperature. Crystals were mounted on a Rigaku AFC10K Saturn 944+ CCD-based X-ray diffractometer equipped with a low temperature device and Micromax-007HF Cu-target micro-focus rotating anode (λ = 1.54187 Å) operated at 1.2 kW power (40 kV, 30 mA). The X-ray intensities were measured at 85(1) K with the detector placed at a distance 42.00 mm from the crystal. d*trek images were exported to CrysAlisPro for processing and corrected for absorption. 55,56 The analysis of the data showed a negligible decay during the data collection. The structures of Sm2nha8, Dy2moshi8 and Tb2mshi8 MCs were solved and refined with the Bruker SHELXTL (version 2018/3) software package. [START_REF] Sheldrick | Crystal Structure Refinement with SHELXL[END_REF] All non-hydrogen atoms were refined anisotropically with the hydrogen atoms placed in idealized positions.

Sm2nha8: [Sm2Ga8(nha)8(iph)4]Na2 •14H2O •14DMF. Yield: 165 mg (59%
The SQUEEZE subroutine of the PLATON [START_REF] Spek | Structure Validation in Chemical Crystallography[END_REF][START_REF] Spek | Single-Crystal Structure Validation with the Program PLATON[END_REF] program suite was used in each case to address some of the disordered solvent molecules contained in solvent accessible voids present in the structure which are common in this type of macromolecular complex. [START_REF] Martinić | Near-Infrared Optical Imaging of Necrotic Cells by Photostable Lanthanide-Based Metallacrowns[END_REF][START_REF] Salerno | Visible, Near-Infrared, and Dual-Range Luminescence Spanning the 4f Series Sensitized by a Gallium(III)/Lanthanide(III) Metallacrown Structure[END_REF][START_REF] Wang | Building Block and Directional Bonding Approaches for the Synthesis of {DyMn 4 } n (n = 2, 3) Metallacrown Assemblies[END_REF] Additional details are presented in Table S1, in the Supporting Information, and in CIF files. Crystals of other Ln2L'8 MCs (L' = shi 3- , moshi 3-, mshi 3-) were screened to determine unit cell parameters (Table S2).

Powder X-ray diffraction (PXRD) patterns were acquired for Ln2L'8 MCs using a Rigaku Ultima IV X-Ray Diffractometer (Cu anode, λ = 1.5406 Å) upon scanning from 3 to 15° in 2 θ (Figure S1, Supporting Information).

Thermogravimetric analysis curves for Tb2mshi8, Tb2moshi8, and Tb2nha8 were measured from 30 °C to 900 °C under a N2 atmosphere using a Perkin-Elmer TGA-7 thermogravimetric analyzer at a scan rate of 10 °C/minute (Figure S12). Initial sample masses were between 2.5 and 4.9 mg.

Photophysical properties.

Excitation and emission spectra, luminescence lifetimes, and quantum yields. Luminescence data were collected for relevant Tb 3+ and Sm 3+ samples in the solid state. Emission and excitation spectra were measured on a Horiba-Jobin-Yvon Fluorolog 3 spectrofluorimeter using a visible photomultiplier tube (PMT) (220-800 nm, R928P; Hamamatsu). All spectra were corrected for the instrumental functions. Luminescence lifetimes were determined under excitation at 355 nm provided by a Nd:YAG laser (YG 980; Quantel), the signals of Tb 3+ at 545 nm ( 5 D4 → 7 F5 transition) or Sm 3+ at 597 nm ( 4 G5/2→ 6 H7/2 transition) were detected with a Hamamatsu R928 PMT connected to an iHR320 monochromator (Horiba Scientific). No initial delay was applied and luminescence decay curves were recorded with time intervals of 0.1/0.2 µs for Tb 3+ MCs or 20 ns for Sm 3+ MCs. Representative luminescence decay curves are given in Figure S13. The output signals from the detectors were fed into a 500 MHz bandpass digital oscilloscope (TDS 754C; Tektronix). Luminescence lifetimes are averages of at least three independent measurements. Ln 3+ -centered quantum yields under ligands excitation (Q Ln L ) were determined with a Fluorolog 3 spectrofluorimeter based on the absolute method using an integration sphere (Model G8, GMP SA, Renens, Switzerland). Each sample was measured several times. The experimental error for the determination of quantum yields is estimated as 10 %. Ligand-centered quantum yields (Q L L ) were calculated from the corresponding emission spectra taking into account the values of Q Ln L .

Diffuse reflectance spectra. For the collection of diffuse reflectance spectra, Ln2L'8 MCs (5 wt.%) were thoroughly grounded and dispersed in MgO. Measurements were performed on a Jasco V670 UVvisible spectrophotometer in reflectance (R) mode using a horizontal integration sphere accessory at room temperature. To reflect absorbance, diffuse reflectance spectra are presented as Kubelka-Munk function ((1-R) 2 /2R) vs. wavelength (Figures 3,S14, S15 Supporting Information).

Phosphorescence spectra. Phosphorescence spectra of Gd 3+ compounds were measured on powder samples at 77 K on a Horiba-Jobin-Yvon Fluorolog 3 spectrofluorimeter in time-resolved mode.

Temperature-dependent emission spectra. For measurements ca. 50 mg of relevant Tb 3+ or Sm 3+ powder samples were pressed into a pellet using a hand pellet press. These were affixed to a copper plate attached to a temperature controller via vacuum grease. The temperature dependent emission spectra were recorded on a double grating excitation spectrofluorimeter equipped with a TRIAX 320 emission monochromator (Fluorolog-3, Horiba Scientific) coupled to a R928 Hamamatsu photomultiplier in a front face acquisition mode. The excitation source was a 450 W Xe arc lamp. Emission spectra were corrected for the detection and optical spectral response of the spectrofluorometer. The temperature was controlled by a helium closed cycle cryostat with a vacuum system measuring ca. 5×10 -6 mbar and a Lakeshore 330 temperature controller with a resistance heater. The temperature was adjusted to various settings using the auto-tuning temperature controller from ca. 11 to 400 K with a maximum accuracy of 0.1 K. Emission spectra were collected after waiting for a minimum of 5 minutes to thermalize the sample. A baseline correction was performed on each spectrum by fitting a polynomial function to the background signal and subtracting the fitted function.

Twelve metallacrown complexes were analyzed for their relevant luminescence properties. Each of these compounds are dimeric 12-MC-4 MCs with a similar topology to that shown in Figure 1. The MC units (Figure 2, left) form the dimer when combined with the iph 2-ligand (Figure 2, right). These materials were created using permutations of several different trivalent lanthanide ions (Ln 3+ ) and four MC component ligands (Figure 2, center): H3shi, 5methylsalicylhydroxamic acid H3mshi, 5methoxysalicylhydroxamic acid H3moshi, and 3hydroxy-2-naphthohydroxamic acid H3nha. Each complex has the general formula Ln2Ga8L'8L"4, where Ln = Gd 3+ , Tb 3+ , or Sm 3+ ; L' = shi 3-, mshi 3-, moshi 3-, or nha 3-; and L" = iph 2-. The complexes will be referred to in shorthand here as Ln2L'8 for simplicity (e.g., Sm2shi8). The Ln2shi8 MCs were previously reported for their room temperature luminescence properties [START_REF] Nguyen | One-Step Assembly of Visible and Near-Infrared Emitting Metallacrown Dimers Using a Bifunctional Linker[END_REF] (several previously reported data are provided in this work for comparison with the novel complexes). A new analysis of their thermaldependence of luminescence spectra has been performed. The Ln2mshi8, Ln2moshi8, and Ln2nha8 are all new complexes on which a similar analysis has been performed. Compositions of these complexes have been confirmed by mass spectrometry, elemental analysis, and either single crystal X-ray diffraction or PXRD studies.

For the Tb 3+ and Sm 3+ complexes, measured photophysical properties include diffuse reflectance spectra, excitation spectra, emission spectra (11-400 K), emission lifetimes and quantum yields, at room temperature. Emission properties were determined upon excitation into ligand electronic levels in the UV/visible range. Gd 3+ complexes were synthesized to serve as probes of the ligand-centered electronic structure and were analyzed by recording diffuse reflectance spectra to determine the ligand singlet state energies and phosphorescence spectra to determine the ligand triplet state energies. Such measurement is possible because Gd 3+ possesses excited electronic states generally too high in energy to accept energy from the ligand excited states, and also because Gd 3+ possesses very high spin (ground S=7/2) that may increase the rate of singlet to triplet intersystem crossing within the ligand.

Synthesis. The reaction between Ga(NO3)3, Ln(NO3)3, isophthalic acid, and the MC ring ligand (H3shi, H3mshi, H3moshi, or H3nha) in an appropriate ratio of DMF with a basic salt (NH4HCO3 for Ln2shi8 compounds or NaOH for the others) results in the formation of the desired compounds via selfassembly. These are crystallized out of solution via slow evaporation of the solvent to yield the pure materials.

Crystal Structures. X-ray single crystal structures were solved for at least one Ln 3+ derivative from each Ln2L'8 series, e.g. for Tb2mshi8, Dy2moshi8, and Sm2nha8. For Ln2shi8, the crystal structure of the Dy 3+ analogue was previously reported. [START_REF] Katagiri | Thermo-Sensitive Luminescence Based on the Back Energy Transfer in Terbium(III) Complexes[END_REF] For the remaining Ln2L'8 MCs (L' = shi 3-, moshi 3-, mshi 3-), their unit cells were determined by screening single crystals by X-ray diffraction (Table S2). For the Ln2L'8, only the Sm 3+ analogue produced crystals suitable for single crystal X-ray diffraction. Tb2nha8 and Gd2nha8 MCs were obtained as microcrystalline materials. To confirm the structural uniformity within the Ln2nha8 series, the corresponding PXRD patterns were acquired and compared with those calculated from the respective crystal structures (Figure S1). The collected data allowed to establish a global description of the MC structure for each series, independently of the nature of Ln 3+ .

The crystal structures of Ln2L'8 and packing diagrams are shown in Figures S2-S10. Each compound has a similar overall topology dictated by the identical ligand binding motifs, resulting in dimeric structures like the one presented in Figure 1. The isostructural nature of these complexes indicates that differences in the energy levels of the lanthanides due to crystal field effects will be minimal and that most of the relevant differences in properties are due to the interaction of the Ln 3+ excited states with the ligand excited states. According to a SHAPE analysis, the local environment around each Ln 3+ is best described as a square antiprism that is constituted of eight oxygen atoms (Tables S5-S18). [START_REF] Cirera | Continuous Shape Measures as a Stereochemical Tool in Organometallic Chemistry[END_REF][START_REF] Llunell | Shape. Version 2.1[END_REF] Four of these atoms are carboxylate oxygens derived from isophthalate groups, while the other four oxygen donors are oxime oxygens located in the MC plane. In each case, the isophthalic acid mean plane is closer to the Ln 3+ than the oxime oxygen plane, ca. 1.1 Å versus 1.5 Å, respectively (Table S3). The intramolecular Ln 3+ -Ln 3+ distance varies between 7.010-7.215 Å, while the shortest intermolecular distance between Ln 3+ is at least 12.8 Å (Table S4). Thermogravimetric analysis. Thermogravimetric curves for Ln2L'8 MCs (L' = shi 3-, moshi 3-, mshi 3-, nha 3- ) are presented in Figure S12. Water and DMF are cocrystallized with the present compounds. All samples show gradual or step-wise weight loss from 30 °C to 200-300 °C associated with the baking of solvent molecules from the lattice, followed by a leveling off until 400-500 °C. Finally, the molecular thermal decomposition occurs above this temperature. These results suggest that MC scaffolds are thermally stable until at least 400 °C (673 K).

Diffuse reflectance spectra. The diffuse reflectance spectra were collected for all studied MCs (Figure S14, S15, Supporting Information), the spectra corresponding to the Gd 3+ derivatives are given in Figure 3. For each L' ligand, the spectra are quite similar for all three examined Ln 3+ , so we will focus on Gd 3+ MCs. We consider the red edge of the spectrum as the singlet state of lowest energy (S1). The singlet energies determined in this manner for each compound are gathered in Table 2.

Phosphorescence spectra of Gd 3+ complexes. Phosphorescence spectra were collected for each Gd 3+ derivative at 77 K upon excitation into the ligand absorption band between 310-400 nm. The spectra are given in Figure S16. Each phosphorescence spectrum was fitted as a sum of Gaussian curves. The lowest in energy Gaussian band was considered as the zero-phonon (0-0) transition was assigned as the energy of the triplet state of lowest energy (T1). These results are gathered in Table 2. Excitation and emission spectra measured at room temperature. Excitation and emission spectra of Tb2L'8 and Sm2L'8 MCs were recorded in the solid state at room temperature. Excitation spectra upon monitoring emission of Tb 3+ at 545 nm ( 5 D4→ 7 F5 transition) and Sm 3+ at 597 nm ( 4 G5/2→ 6 H7/2 transition) are given in Figures S17 andS18 (left), respectively. Emission spectra upon excitation at 340-370 nm are given in Figure 4. Notably, Tb 3+centered emission in Tb2nha8 was not observed, while for Sm2nha8 a broad band in the range 400-600 nm attributed to the ligand fluorescence was detected along with weak sharp Sm 3+ -centered bands. Emission profiles of Tb2L'8 and Sm2L'8 MCs are independent of the nature of the ligands, being consistent with the locally isostructural coordination environment around each Ln 3+ . Tb2L'8 MCs show characteristic emission bands arising from 5 D4→ 7 FJ transitions, with the main emission bands attributed to 5 D4→ 7 F6 (490 nm), 5 D4→ 7 F5 (545 nm), 5 D4→ 7 F4 (585 nm), 5 D4→ 7 F3 (620 nm), and emission bands with lower intensities assigned to 5 D4→ 7 F2 (650 nm), 5 D4→ 7 F1 (670 nm), and 5 D4→ 7 F0 (680 nm). Sm2L'8 MCs demonstrate characteristic emission signals arising from 4 G5/2→ 6 HJ transitions, with bands located 4 G5/2→ 6 H5/2 (555 nm), 4 G5/2→ 6 H7/2 (600 nm), 4 G5/2→ 6 H9/2 (645 nm), and 4 G5/2→ 6 H11/2 (700 nm). For the Sm2shi8, Sm2mshi8, and Sm2moshi8 compounds, emission in the near infrared (NIR) range was also (Figure S18, right).

Table 1. Luminescence lifetimes (τobs), Ln 3+ -centered quantum yields (𝑸 Ln L ) and ligand-centered quantum yields (𝑸 L L ) in the visible range of Tb2L'8 and Sm2L'8 MCs (L' = shi 3-, moshi 3-, mshi 3-, nha in % are given after the colon. c Calculated from the emission spectrum d From Ref. [START_REF] Nguyen | One-Step Assembly of Visible and Near-Infrared Emitting Metallacrown Dimers Using a Bifunctional Linker[END_REF] e Under excitation at 350 nm. f Could not be determined due to insufficient signal. g Under excitation at 370 nm.

Quantum yields and Ln 3+ luminescence lifetimes at room temperature. Quantum yields under ligand excitation of (i) Ln 3+ -centered emission (𝑄 𝐿𝑛 𝐿 ) and (ii) ligand-centered emission (𝑄 𝐿 𝐿 ) were determined for Ln2mshi8, Ln2moshi8, and Ln2nha8 (Ln = Tb 3+ , Sm 3+ ) in the solid state. Additionally, Ln 3+ luminescence lifetimes (τobs) were determined for all studied MCs except Sm2nha8, which exhibited a very weak emission. These parameters are gathered for visible emissions in Table 1. Quantum yields for near infrared emission from Sm 3+ compounds are given in Table S19. Thermal dependence of Ln 3+ emission intensities. For all MCs exhibiting Tb 3+ -or Sm 3+ -centered transitions, emission spectra were collected in the temperature range from 11 to 400 K on solid-state samples. As an example, the thermal dependence of the Tb 3+ emission in Tb2moshi8 is given in Figure 5 (left). The emission intensity of each band decreases upon heating. In Figure 5 (right), the normalized integrated intensity of each 5 D4→ 7 FJ transition band as a function of temperature given. All bands possess identical thermal dependence when normalized.

The thermal dependence was analyzed in a similar way for all complexes; those data are summarized in Figures S19-S25. The analysis of the thermal dependence of integrated intensities of a representative prominent band for Tb2L'8 and Sm2L'8 MCs is given in Figure 6. A plot displaying the temperature-dependent emission spectra focusing on the 5 D4 → 7 F5 transition for Tb 3+ complexes and the 4 G5/2 → 6 H7/2 transition for Sm 3+ complexes is given in Figure S27.

Analysis of a molecular thermometer based on mixed

Tb2moshi8/Sm2moshi8. The Tb2moshi8 and Sm2moshi8 complexes were combined to create a ratiometric luminescent nanothermometer. This was accomplished by a thorough grinding of Tb2moshi8 and Sm2moshi8 in a 1:1 ratio in a mortar. The thermaldependent luminescence was examined upon excitation at 370 nm (Figure 7 A). We observe some overlap between the Sm 3+ and Tb 3+ emission profiles, particularly between the Tb 3+ 5 D4 → 7 F4/ 4 G5/2→ 6 H7/2 and the 5 D4 → 7 F2/ 4 G5/2→ 6 H9/2 transitions. In andS26). The excitation wavelength was 340 nm for Ln2shi8, 350 nm for Ln2mshi8, 370 nm for Ln2moshi8, and 380 nm for Ln2nha8. where T is the temperature, a1 is a dimensionless scaling factor, E1 is the energy gap between the accepting and donating energy levels, and Δo is the maximum intensity of this parameter at low temperatures (before the thermally-dependent quenching pathway activates). The fitting parameters are gathered in Table S22. An analogous dualpathway component Mott-Seitz model can be fit as well (eqn S1, Table S23) with similar results. A full theoretical consideration may incorporate many relevant de-activation pathways (vide infra) but this simpler model fit the thermal response well in this case. Lastly, Figure 7 D shows the relative (thermal) sensitivity of this thermometer (Sr) calculated according to

𝑆 𝑟 = 1 Δ | ∂Δ 𝜕𝑇 | eqn 2
Figure 7. A: thermal dependence of emission spectra for a 1:1 molar mixture of Tb2moshi8 and Sm2moshi8 from 11 (black) to 400 K (red) under excitation at 370 nm. The Tb 3+ transitions are identified in black text and the Sm 3+ ones in green. B: integrated intensities of Tb 3+ and Sm 3+ transitions vs. temperature. The integration boundaries are indicated in panel A. For the red integration area, the label "Sm 3+ : 4 G5/2→ 6 H9/2" is indicated because the emission intensity in this spectral region is mainly due to this band, however, the low-intensity "Tb 3+ : 5 D4 → 7 F2" transition also occurs within this region. C. The Δ parameter is calculated by taking the fraction specified in the legend for each temperature. The fit for each curve is overlaid in black (eqn 1). D: The relative sensitivity for each Δ parameter calculated from 2.

Emission spectra and quantum yields. The emission spectra of Tb2L'8 and Sm2L'8 MCs are quite similar and independent of the nature of the hydroximate ligands. This result can be understood by the locally isostructural environment around each Ln 3+ center. A C4v-type geometry exists around each Ln 3+ in Ln2L'8 MCs, although it is crystallographically C4v for the Ln2nha8 and Ln2mshi8 compounds and only pseudo-C4v for the Ln2moshi8 and Ln2shi8 compounds. The small differences in the coordination environment around each Ln 3+ ion due to the electronic properties of the ligands are apparently minimally important in shaping the emission spectra of each Ln2L'8 MCs.

A correlation can be established between the photophysical properties of Ln2L'8 MCs and the relative positions of the levels of the ligands (S1, T1) in respect to the accepting levels of the corresponding Ln 3+ , i.e. 5 D4 (20400 cm -1 ) for Tb 3+ and 4 G5/2 (17800 cm -1 ) for Sm 3+ . Those data are summarized in Table 2. For the Tb2nha8 complex, an absence of Tb 3+ -centered emission is expected considering that the donating T1 state of nha 3-ligand lies below the 5 D4 state of Tb 3+ . When the 5 D4 state is occupied, there is a very efficient deactivation route via energy transfer to the lower-lying T1 state and/or the sensitization of the Tb 3+ via the feeding from the T1 state cannot occur given the lower energy position of the T1 state. 1) and the visible emission spectrum shows significant broad ligand-centered bands compared to the Sm 3+ -centered transitions (Figure 4). The very low quantum yield value recorded for Sm 3+ in Sm2nha8 can be understood by the small energy gap (ΔE = 350 cm -1 ) between the 4 G5/2 state of Sm 3+ and the T1 state of the nha 3- ligand, enhancing the probability of a back energy transfer. For other studied Sm2L'8 MCs, the energy differences between the corresponding T1 levels and the 4 G5/2 state are more than 3770 cm -1 and they exhibit very similar values of 𝑄 𝑆𝑚 𝐿 (2.0-2.3 %).

In the case of Tb2L'8 MCs (L' = shi 3-, moshi 3-, mshi 3-), the variability of 𝑄 𝑇𝑏 𝐿 is larger, ranging from 2.07(6) to 31.2(2) % (Table 1), owing to the closer proximity between the ligand energy levels and the emissive 5 D4 energy level of Tb 3+ . In general, the values of 𝑄 𝑇𝑏 𝐿 correlate directly with the energy gap between the donating T1 and accepting 5 D4 levels. That is, the smaller the energy gap ΔE(T1-5 D4), the smaller the room temperature 𝑄 𝑇𝑏 𝐿 due mainly to the higher probability of back-energy transfer to the energy states of the ligand. We can note, however, that while Tb2mshi8 and Tb2moshi8 possess fairly similar T1 energy levels (21570 cm -1 and 21640 cm -1 , respectively), the 𝑄 𝑇𝑏 𝐿 values are significantly different, 25.2(4) % for Tb2mshi8 vs. 2.07(6) % for Tb2moshi8. Thus, we can conclude that the energy transfer involving the S1 state is also important, since the S1 energy levels are more disparate (26900 cm -1 for Tb2mshi8 vs. 25400 cm -1 for Tb2moshi8). This conclusion will be described in more detail below.

Thermal dependence of emission. The luminescence spectra of Ln2L'8 MCs were recorded in a broad range of temperatures from 11 to 400 K. As temperature increases, most of the compounds show an emission intensity that is generally minimally affected until a certain temperature is reached, where a significant thermally activated decrease occurs, consistent with the Boltzmann-dependent nonradiative de-activation mechanism.

Considering the Sm 3+ compounds, the onset of intensity decrease occurs at low temperatures for Sm2nha8, and at temperatures greater than ~350 K for the other Sm 3+ MCs. For Sm2nha8, a significant decrease starts around 75 K, although it is not fully apparent from the collected data that the temperature change was flat below to this temperature, as the lowest available temperature point is 11 K. The low temperature onset of this decrease can be understood from the small energy gap (ΔE = 350 cm -1 ) between the donating T1 state of the ligand and the accepting 4 G5/2 state of Sm 3+ . This small gap indicates that the Boltzmann-dependent back energy transfer will occur at low temperatures. For the other Sm 3+ MCs, their intensity decrease trend is not complete within the experimental temperature range. However, each compound initiates a temperature decrease around 350 K. The similarity of the temperature decrease onset for each of these MCs, despite a variety of ligand energy levels, suggests that the intensity decrease in these cases may be primarily due to mechanisms that may be additional to the electronic-based energy transfer. Thermally activated vibrational modes may be the most relevant non-radiative deactivation mechanisms owing to the similarity of the molecular structure within Sm2L'8 series. Thermally activated solvent loss may also be relevant at high temperatures (see TGA, Figure S12).

For the Tb 3+ complexes, the variation in thermally dependent emission intensity behaviors as related to the energy levels of the ligand states is more apparent than for the Sm 3+ complexes. The intensity decrease begins around 150 K for Tb2moshi8, 250 K for Tb2mshi8, and 300 K for Tb2shi8. This trend correlates well with the energy gap between the ligand-based energy levels and the 5 D4 state of Tb 3+ in each case. For the S1 energy level of the ligand: shi 3- > mshi 3-> moshi 3-. For the T1 energy level: shi 3-> mshi 3-≈ moshi 3-. Thus, given the differences in 𝑄 𝑇𝑏 𝐿 values discussed above, energy transfer dynamics considering the S1 as well as the T1 state are quite relevant. Otherwise, only the T1 states would be important and the Tb2moshi8 and Tb2mshi8 MCs would have similar thermal responses and 𝑄 𝑇𝑏 𝐿 at room temperature since the T1 energy levels are similar for Tb2moshi8 and Tb2mshi8 MCs.

To examine the importance of the relative energy levels in each emissive compound in detail, theoretical calculations were performed. The thermal response of each material was calculated considering Judd-Ofelt theory, intramolecular energy transfer (IET) theory, and population rate equations. The full theoretical analysis can be found in the Supporting Information; however, a summary of the results is given here (Figure 8). For most of the Tb 3+ -based MCs, the temperature-dependent behavior can be understood as a competition between forward and backward rates via energy transfer involving the S1 state (𝑊 𝑆 and 𝑊 𝑆 𝑏 , Table S35). On the other hand, for the Sm 3+ -based MCs, the energy transfer from the T1 state was shown to be more efficient and the forward rate (𝑊 𝑇 ~10 9 𝑠 -1 ) increases with the temperature for all cases. Figure S33 summarizes the thermal behavior of some important rates.

Among all of the studied MCs, the Ln2moshi8 is a special case in which the energy transfer dynamics between the T1 and S1 states of the moshi 3-ligand are especially important. This observation is based on the close energetic proximity of these electronic states ΔE(S1-T1) = 3760 cm -1 , promoting a reverse intersystem crossing rate T1 → S1 (𝑊 𝑟𝐼𝑆𝐶 ). [START_REF] Samanta | Up-Conversion Intersystem Crossing Rates in Organic Emitters for Thermally Activated Delayed Fluorescence: Impact of the Nature of Singlet vs Triplet Excited States[END_REF][START_REF] Wang | Theoretical Characterizations of TADF Materials: Roles of ΔG and the Singlet-Triplet Excited States Interconversion[END_REF] Thus, the 𝑊 𝑟𝐼𝑆𝐶 becomes commensurate with the direct process (𝑊 𝐼𝑆𝐶 ) and imposes a thermally dependent rate competition between them (Figure S34). In other words, as the temperature increases, 𝑊 𝑟𝐼𝑆𝐶 becomes competitive with 𝑊 𝐼𝑆𝐶 , so the T1 state becomes less populated and can no longer transfer as much energy to the Tb 3+ , decreasing the population of the 5 D4 level (Figure S35). If the effect of 𝑊 𝑟𝐼𝑆𝐶 is not considered, only the backward energy transfer via S1 (𝑊 𝑆 𝑏 ) is sensitive to the temperature (𝑊 𝑆 𝑏 ranging from 1.15×10 5 to 1.81×10 6 s -1 ), which is not substantial enough to produce the rapid Tb 3+ emission quenching pattern observed experimentally when the temperature raises for Tb2moshi8 (Figure S28). On the other hand, the competition between 𝑊 𝐼𝑆𝐶 and 𝑊 𝑟𝐼𝑆𝐶 does not affect too much the Sm2moshi8 once the rates T1⇄Sm 3+ (𝑊 𝑇 and 𝑊 𝑇 𝑏 , Table S35) are faster than the estimated 𝑊 𝐼𝑆𝐶 and 𝑊 𝑟𝐼𝑆𝐶 (Figure S34).

Therefore, the energy transfer in both directions across the S1-T1 energy gap is a highly important mechanism for the induction of a thermal dependence of the emission intensity in competition with the Ln 3+ to T1 mechanism which has been previously identified. [START_REF] Gálico | Triplet-State Position and Crystal-Field Tuning in Opto-Magnetic Lanthanide Complexes: Two Sides of the Same Coin[END_REF][START_REF] Deiters | Luminescent Bimetallic Lanthanide Bioprobes for Cellular Imaging with Excitation in the Visible-Light Range[END_REF][START_REF] Latva | Correlation between the Lowest Triplet State Energy Level of the Ligand and Lanthanide(III) Luminescence Quantum Yield[END_REF][START_REF] Katagiri | Energy-Transfer Mechanism in Photoluminescent Terbium(III) Complexes Causing Their Temperature-Dependence[END_REF] Based on these results, one may consider adjusting the ligand S1-T1 gap to induce changes in the thermal dependence of thermometer, or to increase quantum yields of emission. In the present case, this process does not greatly affect the Sm2moshi8 because it holds the 𝑊 𝑇 > 𝑊 𝑟𝐼𝑆𝐶 relation for any temperature considered. The 𝑊 𝑟𝐼𝑆𝐶 is negligible for each of the other ligands due to high ΔE(S1-T1) (> 5000 cm -1 ).

It is important to keep in mind that large forward rates (from ligand to the Ln 3+ ) will not grant necessarily to the system excellent optical properties, and that the entire set of competing rates are difficult to generalize heuristically. This set can only be examined with the help of population rate equations (eqns. S20-S24) that take into account all rates involved (absorption, ISC, rISC, forward IET, backward IET, and luminescence decay lifetimes), as depicted in Figure 8.

Knowing the thermal behavior of the population of the emitting level for both Tb 3+ and Sm 3+ (Table S36), it is possible to model the Δ parameters. Figure 9 shows the theoretical curves for a 1:1 mixture of Tb2moshi8:Sm2moshi8. It is notable the similarity between the theoretical Δ with the experimental ones (Figure 7C). The separations between the three curves are related to the differences in the radiative components for each Tb 3+ 5 D4 → 7 FJ transition (J = 3, 5, and 6). It is worth highlighting that the theoretical modeling procedure presented here is general and capable of estimating the relative population of emitting levels of any Ln 3+ ion, and therefore, the emission intensity (or ratio between two intensities). This feature opens perspectives in the rational design of new luminescence Ln 3+ -based materials before realizing synthetic routes. The comparison between the temperature-dependent emission profiles of the 5 D4 → 7 F5 transition for Tb2L'8 MCs and the 4 G5/2 → 6 H7/2 transition for Sm2L'8 MCs are presented in Figure S27. We can observe that the intensity of the Tb 3+ transition decreases as temperature increases while maintaining an overall similar spectral profile, while for the Sm 3+ complexes, the profile of the 4 G5/2 → 6 H7/2 transition broadens noticeably throughout the experimental temperature range even if the emission intensity is relatively constant. This behavior is consistent with the thermal population and the emission from excited states located lower -lying above the lowest-energy emitting level of Sm 3+ as temperature increases. For Tb 3+ , maintaining the same spectral profile suggests that the electronic states above the 5 D4 emitting level are not populated as temperature increases.

It is worth mentioning that when the S1 is repopulated by the reverse ISC (rISC) pathway, the competition between S1→S0 and S1→Ln 3+ is considered in the numerical simulations (coupled system of rate equations). The first process prevails over the second one theoretically and experimentally. Otherwise, if (𝜏 𝑆 ) -1 < 𝑊 𝑆 , an increase of the Tb 3+ 5 D4 population (and consequently Tb 3+ emission) would be expected with the increase of the rISC when the temperature rises (Figure S34).

Analysis of thermometric device capacity. One may notice than any permutation of the present compounds could be used to create a luminescent thermometer provided that one of the emitters (Sm 3+ , in this case) has a relatively constant response to temperature (to serve as a calibration) and the other (Tb 3+ ) has a decrease in intensity in the region of interest. Thus, because the present set of Ln2L'8 MCs has a variability in the location of the thermal dependence throughout the cryogenic to 400 K range, these materials represent a way to create luminescent thermometers for use in an arbitrary temperature range.

As an example, a 1:1 mixture of Tb2moshi8:Sm2moshi8 was combined in the solid state to demonstrate the thermometric capacity of the present complexes by mixing two independent materials. The thermometric analysis described above (eqn 2) led to a luminescent molecular thermometer with a maximal sensitivity Sr around 3 %K -1 at 220 K, but Sr > 1.5 %K -1 for ca. 200-300 K (Figure 7). Since the thermal dependence is controlled mainly by the Tb 3+ , by using a different Tb 3+ -based compound, we can access a broad temperature range for thermometric activity. For example, we can expect a Sr that is larger than 1.5 %K -1 throughout the biologically relevant range 300-350 K by using Tb2mshi8 (Figure S29). Thermogravimetric analysis of Ln2L'8 revealed that these dimeric MCs are very robust, being thermally stable up to at least 650 K (Figure S12).

When using intensity-based luminescence thermometry, a second emitter is necessary to allow the internal calibration of the thermometric response, as abovementioned. As in the present case, the second ("calibrating") emitter does not need to be covalently attached to the active (thermally responsive) center if these emitters are evenly dispersed within the environment of interest. Although one may think about covalent bonding of the two emissive centers (thermally active and calibrating), this may not necessarily be beneficial versus the simpler approach of using two independent types of molecules. For the presented MCs and many other thermometric systems, Boltzmann dependent energy transfer is the relevant thermally active mechanism. [START_REF] Suta | A Theoretical Framework for Ratiometric Single Ion Luminescent Thermometers-Thermodynamic and Kinetic Guidelines for Optimized Performance[END_REF] As a statistical process, a Boltzmann dependent mechanism requires an ensemble of emitters to allow the accurate correlation of intensity with the temperature.

Molecular-based thermometers composed of two independently emissive Ln 3+ are promising because they offer the sensitivity of a dual-centered ratiometric optical nanothermometer: the two emissions used for analysis can be independently modified, and the molecule itself can be functionalized via chemical techniques. For example, in a previous communication, we showed that one may combine 1:1 Sm2shi8:Tb2shi8 in polystyrene nanobeads to create a water-compatible compound with thermometric activity in a biologically relevant range, 300-330 K. [START_REF] Salerno | Ga3+8Sm3+2, Ga3+8Tb3+2] Metallacrowns Are Highly Promising Ratiometric Luminescent Molecular Nanothermometers Operating at Physiologically Relevant Temperatures[END_REF] Twelve Ln 3+ -based metallacrowns (Ln2L'8, L' = shi 3-, moshi 3-, mshi 3-, nha 3-) were analyzed for their optical properties, including nine newly synthesized complexes. Three new molecular scaffolds were presented (Ln2moshi8, Ln2mshi8, Ln2nha8), along with a previously described Ln2shi8 MCs. The Gd 3+ , Sm 3+ , and Tb 3+ complexes were presented in each case, and the temperature response of the Ln 3+ -based photoluminescence was measured for the Sm 3+ and Tb 3+ complexes. The analysis of the diffuse reflectance and phosphorescence spectra of the corresponding Gd 3+ MCs allowed the determination of the ligand S1 and T1 energy levels. It was generally found that the energy gap ΔE between the Ln 3+ excited state and the ligand excited T1 state is correlated with the temperature of onset of the reduced emission intensity. The smaller ΔE led to a decrease of the emission intensity, which was onset at lower temperatures consistent with a Boltzmann-dependent back transfer mechanism. Furthermore, theoretical calculations allowed the identification of an important T1 to S1 back energy transfer mechanism for thermally-dependent deactivation of the Tb2moshi8 complex. The difference in energies T1-S1 together with Ln 3+ *-T1 represent an important parameter for creating thermally active luminescent materials. This approach is advantageous because it is based on a purely molecular mechanism, independent of the properties of the bulk material.

It was shown that within the studied series of MCs, a thermal response could be modulated across the cryogenic to 400 K range. In addition, by combining MCs with different thermal dependence, an optical ratiometric thermometer could be produced. Such thermometer functionality was demonstrated with the 1:1 Tb2moshi8:Sm2moshi8 system in the solid state, which had a maximum relative thermal sensitivity Sr of about 3 %K -1 at 220 K but Sr > 1.5 %K -1 in the range 200-300 K. The presented approach of combining two materials with a disparate thermal response could be generally translated for other classes of compounds to create optical thermometers with controlled properties and improved performance. Due to the tunability of the temperature range via synthetic considerations, physical processes which are active at different thermal ranges can be accessed with the present scheme. For example, a Tb2mshi8-based system can be expected to have a high thermal sensitivity at ca. 300 K (Figure 6), i.e. in a biologically relevant range. A combination of this MC with an appropriate partner complex such as Sm2mshi8 could allow to create a ratiometric thermometer.

Crystallographic information files (.cif) for Tb2mshi8 (CCDC 2170006), Sm2nha8 (CCDC 2170007), and Dy2moshi8 (CCDC 2170008).

Experimental details, synthesis and characterization of Ln-1 MCs, X-ray crystallographic parameters, supplementary tables, figures describing photophysical properties, and theoretical analysis details are available in supporting information (PDF).

Figure 1 .

 1 Figure 1. Top-down (left) and side-on (right) views of the Ln2nha8 complex. The structure is a dimer of two 12-MC-4 MC units linked by four isophthalic acid bridges. The Ln[-Ga 3+ -N-O-]4 motif is highlighted.Color code: Ga, pink; Ln, green; O, red; N, blue; C, grey. Solvents, counter cations, and hydrogen atoms are omitted for clarity. This structure was obtained on Xray single crystal diffraction on the Sm 3+ analogue.

Figure 2 .

 2 Figure 2. Left panel: schematic representation of a Ln 3+ [12-MCGa III (N)(shi)-4] MC unit. The -[Ga 3+ -N-O]4-ring motif is in bold. Center panel: representation of the four hydroxamic acids used in the present study, H3L'. Each trianionic ligand forms analogous MC structures due to the identical binding motifs. Right panel: representation of the isophthalic acid, which acts as a bridging ligand and binds as iph 2-resulting in the formation of a dimeric structure as in 2. Binding atoms are presented in color.

Figure 3 .

 3 Figure 3. Diffuse reflectance spectra of Gd2L'8 MCs (L' = shi 3-, moshi 3-, mshi 3-, nha 3-) presented as Kubelka-Munk function vs. wavelength. Spectra are normalized to the lowest energy peak in the spectral range of 290-425 nm.

Figure 4 .

 4 Figure 4. Corrected and normalized emission spectra for Tb2L'8 and Sm2L'8 MCs (L' = shi 3-, moshi 3-, mshi 3-, nha 3-) in the solid state upon excitation at 340-370 nm at room-temperature.

Figure 5 .

 5 Figure 5. Left: thermal dependence of emission spectrum for Tb2moshi8 from 11K (black) to 400K (red) under excitation at 370 nm. Several temperature traces are omitted for clarity. Right: Normalized integrated intensities of each transition vs. temperature. The inset shows the non-normalized basis. See Figure S21 for integration bounds.

Figure 7 C 1 Figure 6 .

 716 Figure 6. Integrated emission intensities of 5 D4→ 7 F5 and 4 G5/2→ 6 H7/2 transitions vs. temperature for Tb2L'8 and Sm2L'8 MCs (L' = shi 3-, moshi 3-, mshi 3-, nha 3-), respectively. For Sm2nha8, data are not given above 215 K due to the difficulty in obtaining a signal above the baseline beyond this temperature (see FiguresS25 and S26). The excitation wavelength was 340 nm for Ln2shi8, 350 nm for Ln2mshi8, 370 nm for Ln2moshi8, and 380 nm for Ln2nha8. where T is the temperature, a1 is a dimensionless scaling factor, E1 is the energy gap between the accepting and donating energy levels, and Δo is the maximum intensity of this parameter at low temperatures (before the thermally-dependent quenching pathway activates). The fitting parameters are gathered in TableS22. An analogous dualpathway component Mott-Seitz model can be fit as well (eqn S1, TableS23) with similar results. A full

67

 67

Figure 8 .

 8 Figure 8. Simplified energy level diagrams for Ln2moshi8. a) Ln = Tb 3+ and b) Ln = Sm 3+ . 𝜙 is the rate of population of the singlet state upon absorption of the excitation light (S0 → S1), 𝑊 𝐼𝑆𝐶 is the S1 → T1 intersystem crossing rate while 𝑊 𝑟𝐼𝑆𝐶 is the rate of the reverse process (T1 → S1). 𝑊 𝑆 and 𝑊 𝑇 are the forward IET rates from the S1 and T1 states, respectively. Their backward IET rates are the ones with the superscript b (𝑊 𝑏 ). 𝑊 3→4 is the decay rate from Ln 3+ upper levels to the emitting one, |3⟩ → |4⟩. The luminescence lifetimes 𝜏 𝑆 , 𝜏 𝑇 , and 𝜏 are related to the S1, T1, and Ln 3+ states, respectively.

Figure 9 .

 9 Figure 9. Theoretical thermometric Δ parameters (A) and sensitivity (B) for 1:1 Tb2moshi8:Sm2moshi8. Compare to experimental results (Figure 7 C, D).

  ). ESI-MS, calc. for [M] 2-, Sm2Ga8C120H64N8O40, 1558.8; found, 1558.8. Anal. Calcd. for Sm2Na2Ga8C162H190N22O68: C, 43.84; H, 4.32; N, 6.94. Found: C, 43.93; H, 4.43; N, 6.94. 68%). ESI-MS, calc. for [M] 2-, Tb2Ga8C120H64N8O40, 1567.3; found, 1566.8. Anal. Calcd. for Tb2Na2Ga8C156H178N20O67: C, 43.38; H, 4.15; N, 6.49. Found: C, 43.48; H, 4.23; N, 6.49.

	Gd2nha8: [Gd2Ga8(nha)8(iph)4]Na2 •12H2O •11DMF.
	Yield: 160 mg (61%). ESI-MS, calc. for [M] 2-,
	Gd2Ga8C120H64N8O40, 1564.8; found, 1564.8. Anal.
	Calcd. for Gd2Na2Ga8C153H165N19O63: C, 43.80; H, 3.96;
	N, 6.34. Found: C, 43.79; H, 4.06; N, 6.22.
	Tb2nha8: [Tb2Ga8(nha)8(iph)4]Na2 •15H2O •12DMF.
	Yield: 185 mg (

  3-) in the solid state. a

	MC	τobs (µs) b	𝑸 Ln L (%)	𝑸 L L (%) c
	Tb2shi8	1410(1) d	31.2(2) d,e	0.105(1)
	Tb2mshi8	869(2): 92.2(8)%	25.2(4) e	0.106(1)
		217(3): 7.8(8) %
	Tb2moshi8	71.6(9): 74.0(5)%	2.07(6) e	0.11(1)
		16.1(6): 26.0(5)%
	Sm2shi8	117(1) d	2.09(5) d,e	0.038(1)
	Sm2mshi8	76(1)	2.21(2) e	0.068(1)
	Sm2moshi8	83(3)	2.27(5) e	0.07(1)
	Sm2nha8	-f	0.0267(7) g	0.152(4)
	a At room temperature, 2σ values between parentheses. Estimated experimental errors: τobs,
	±2%; 𝑄 Ln L , ±10 %; 𝑄 L L , ±10 %. b Under excitation at 355 nm. If a biexponential decay was 𝐵 𝑖 𝜏 𝑖 observed, population parameters 𝑃 𝑖 = ∑ 𝐵 𝑖 𝜏 𝑖 𝑛 𝑖=1

Table 2 .

 2 Ligand-centered S1 and T1 energy levels, the lowest emitting levels of Sm 3+ ( 4 G5/2) and Tb 3+ ( 5 D4), and relevant energy gaps. 17800 cm -1 . 66 b 20400 cm -1 . 66 Among Sm2L'8 MCs, Sm2nha8 exhibits the lowest 𝑄 𝑆𝑚

	Energy (cm -1 )	Ln2shi8	Ln2mshi8	Ln2moshi8	Ln2nha8
	S1	27800	26900	25400	23300
	T1	21980	21570	21640	18150
	ΔE(S1-T1)	5820	5330	3760	5150
	ΔE(S1-4 G5/2 a )	10000	9100	7600	5500
	ΔE(T1-4 G5/2 a )	4180	3770	3840	350
	ΔE(S1-5 D4 b )	7400	6500	5000	2900
	ΔE(T1-5 D4 b )	1580	1170	1240	-2250

a 𝐿 (Table

This research was supported in part by the National Science Foundation (NSF) under grants CHE-1664964 (V.L.P.), CHE-0840456 (X-ray instrumentation), and DGE-1256260 (E.V.S). EVS thanks Rackham Graduate School (University of Michigan) and the Chateaubriand Fellowship of the Office for Science & Technology of the Embassy of France in the United States. This work was developed within the scope of the projects CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020, and The Shape of Water (PTDC/NAN-PRO/3881/2020) financed by national funds through the FCT/MCTES (PIDDAC). The work in France was partially supported by Ligue Régionale Contre le Cancer, comité du Loiret et d'Eure-et-Loir, the network «Molécules marines, métabolisme et cancer» from the Cancéropôle Grand Ouest. S.P. acknowledges support from the Institut National de la Santé et de la Recherche Médicale (INSERM). IET, intramolecular energy transfer; ISC, intersystem crossing; MC, metallacrown; PXRD, powder X-ray diffraction; rISC, reverse intersystem crossing.

TOC artwork

A novel family of optical molecular thermometers has been investigated photophysically and theoretically.


Centre de Recherche de l'École des Officiers de la Gendarmerie Nationale Les espaces urbains concentrent 53% de la population mondiale. Ce chiffre devrait atteindre le seuil de 70% d'ici 2050. Pour mémoire, l'INSEE1 définit la ville comme tout espace présentant une certaine continuité d'habitat, constituée soit d'une commune composée de plus de 2000 habitants, soit de deux ou plusieurs communes sur le territoire desquelles une zone agglomérée comprend plus de 2000 habitants. Les décideurs publics sont confrontés à des défis majeurs : la mobilité urbaine, la demande énergétique et la garantie de la sécurité des habitants. Tout naturellement, le développement de la ville intelligente va modifier de manière substantielle les politiques publiques de sécurité s'agissant aussi bien des systèmes d'information que du contrôle des flux. Parallèlement, ce développement va s'accompagner de la création d'indicateurs pertinents qui seront censés mesurer les points de performance. Précurseur en la matière, la norme ISO 37120 : 2014 relative au « Développement durable des collectivités --Indicateurs pour les services urbains et la qualité de vie » recense pour la première fois, dans un document officiel, les items qui serviront à mesurer les performances dans les domaines fondamentaux.

Les espaces habités auront recours aux architectures intelligentes. Déclinées sur le plan sécuritaire, les architectures intelligentes disposeront de capteurs implantés dans les vecteurs de communication, les lieux publics et les locaux à usage d'habitation ou professionnel. Ces architectures numériques procéderont au recueil d'une multitude de données à forte valeur ajoutée pour les décisions de mise en oeuvre des politiques publiques de sécurité. L'exercice des missions traditionnelles de la gendarmerie va connaître des changements majeurs.

La quantité de données recueillie pose nécessairement la question de la préservation des libertés individuelles, dont le respect de la vie privée est une des composantes majeures. En retour, elle ouvre aussi de formidables opportunités de constatation, de recueil d'indices utiles à la résolution de certains crimes et délits. À ce propos l'avis de la CNIL sur les compteurs communicants dans le pilotage énergétique du logement mérite une attention toute particulière. À ce stade, la sécurité de l'internet des objets connectés a de plus en plus à prendre en compte la possibilité qu'un tiers prenne le contrôle du système de commande d'une application d'architecture intelligente.

La ville intelligente et ses applications dérivées ouvrent un vaste chantier de réflexion et de doctrines pour les années à venir en matière de politique publique de sécurité et de modes d'action dans les missions clés de police administrative et de police judiciaire.

La norme ISO 37120 : Développement durable des collectivités --Indicateurs pour les services urbains et la qualité de vie : Enjeux et perspectives

Une norme est un document contenant des exigences articulées plusieurs volets. Nous assistons à une révision des normes ISO afin de les adapter aux changements du monde et aux attentes des différentes parties. Première dans le genre, la norme ISO 37120, publiée le 14 mai 2014, se propose de répondre aux attentes fortes en matière de recensement et analyse des indicateurs existants sur le développement durable et la résilience des villes. Véritable outil de la performance, la norme 37120 pourrait être l'outil d'évaluation de la qualité des villes et de leur niveau d'avancement par les 17 domaines abordés et les avantages escomptés. Déclinée localement, cette norme constituera un outil de pilotage et de contrôle de gestion des différentes politiques publiques. Il convient de souligner que cette norme est à destination de toute ville, municipalité ou collectivité désireuse d'évaluer sa performance de façon comparable et vérifiable, quels que soient sa taille, sa situation géographique et son niveau de développement.. À l'évidence cette norme aura vocation à s'appliquer sur les zones rurales et péri-urbaines ainsi que les voies de communication. Document élaboré par l'Organisation Internationale de Normalisation (OIT), il a vocation à être révisé, amendé ou complété dans le temps. L'agence française de normalisation (l'AFNOR), chargée de la transcription de ce document, prévoit la publication de la version nationale en avril 2016. Sur les 17 indicateurs principaux retenus, le volet Sécurité repose sur 5 indicateurs de base ou de soutien considérés comme efficients dans ce segment : nombre d'agents pour 100 000 habitants (indicateur de base) , nombre d'homicides pour 100 000 habitants (indicateur de base), atteintes aux biens pour 100 000 habitants (indicateur à l'appui), délai de réponse pour le département de police depuis l'appel initial (indicateur à l'appui), taux d'atteintes aux personnes pour 100 000 habitants (indicateur à l'appui).

Pour lutter efficacement contre les atteintes aux personnes et aux biens, améliorer les délais de réaction entre la survenance d'un événement et la réponse à apporter, les architectures intelligentes apporteront une contribution décisive dans l'efficience des politiques publiques de sécurité.

Les architectures intelligentes, auxiliaires de la sécurité des personnes et des biens

Il n'existe aucune définition officielle de l'architecture intelligente. La doctrine2 a pu définir l'architecture intelligente comme l'ensemble des éléments spatiaux et architecturaux ayant la capacité de répondre intelligemment à l'environnement extérieur ainsi qu'aux besoins des usagers. Ces architectures intelligentes reposent sur un réseau de capteurs sans fil qui récupèrent les données, pierre angulaire de l'architecture intelligente.

Parmi les architectures intelligentes, certaines ont une vocation sécuritaire dès leur conception comme les systèmes de vidéo-protection et la biométrie. La vidéo-protection connaît une évolution de plus en plus sophistiquée qui dépasse largement la fonction initiale de surveillance qui lui était assigné à l'origine. Ainsi, dans un espace donné, doté de contrôles d'accès et de caméras, un centre d'hypervision peut réaliser une prestation de type escorte d'accompagnement pour permettre à une personne de se déplacer en toute quiétude d'un point à l'autre de cet espace connecté.

La sécurisation des espaces à vocation communautaire comportera progressivement un système de dispositif global de sûreté qui intégrera l'ensemble des sous-systèmes : vidéo-surveillance, contrôle d'accès, système anti-intrusion et interphonie dans l'espace public. Le château de Versailles3 est un exemple type de ce que la technologie actuelle est capable de faire en termes de centre d'hypervision. Ce concept serait, sous réserve d'adaptation, transposable quelles que soient la taille et la nature de l'espace à connecter.

La biométrie 4 est le deuxième « silo » intelligent au service de la sécurité. La CNIL définit la biométrie comme « l'ensemble des techniques informatiques permettant de reconnaître automatiquement un individu à partir de ses caractéristiques physiques, biologiques, voire comportementales ». Les données biométriques sont classées en trois catégories qui répondent aux critères suivants : les prélèvements du corps humain (l'ADN, l'odeur corporelle) ; les représentations numériques ou gabarit (l'empreinte digitale ou le contour de la main) ; les attitudes ou comportements (signature manuscrite, frappe sur un clavier)

Les applications opérationnelles en terme de sécurité sont sans limite, notamment la biométrie comportementale. Le Groupe de l'article 295 précise que « les techniques biométriques basées sur le comportement visent à mesurer les caractéristiques comportementales d'une personne. Elles comprennent la vérification de la signature manuscrite, l'analyse de la frappe sur le clavier, l'analyse de la démarche, la manière de marcher ou de se mouvoir, des modèles indiquant une certaine pensée subconsciente comme le mensonge, etc... » Le mobilier urbain offre des opportunités au service des architectures intelligentes. Il en est ainsi des candélabres installés sur la voie publique. Ces objets deviennent de précieux auxiliaires de la sécurité et de l'ordre publics. Maillant depuis plus d'un siècle l'espace public de la métropole jusqu'au hameau, les candélabres constituent, par leur structure et leur implantation, le support idéal de l'infrastructure numérique sans fil qui contrôle, surveille et maintient le monde sensoriel par les données valorisables recueillies par ces capteurs6 . Une liste non-exhaustive permet d'en mesurer rapidement l'intérêt : diffusion d'annonces et d'alertes, captation d'image, comptage de passants, détections de mouvements de foules anormaux, voire spontanés. Ce même éclairage public pourrait être en mesure de fonctionner selon la fréquentation d'une rue et de fournir des informations concernant le nombre d'individus.

Ces quelques cas concrets soulèvent de nouvelles problématiques en terme d'intégrité des systèmes de commande. Le contrôle du système par son légitime utilisateur demeurera le facteur clé de toute réussite dans le déploiement d'architectures intelligentes des espaces connectés. Pénétrer un système informatique qui pilote des fonctions critiques peut avoir des conséquences graves. Le vol par un cambrioleur agissant par effraction « numérique » ne sera pas une vue de l'esprit. L'hypothèse d'un mode opératoire consistant à détourner les systèmes Smart pour savoir si une personne est présente à son domicile et ainsi désactiver les mécanismes de sécurité sera très plausible. Cette mutation exigera que les locaux à usage d'habitation ou professionnel soient inviolables et que les systèmes embarqués le soient tout autant.

Les données personnelles ou publiques, collectées dans le cadre des architectures intelligentes, présentent un caractère valorisable qu'il convient d'encadrer. Sur cette problématique, la CNIL se positionne dès à présent comme l'autorité de régulation incontournable dans la surveillance numérique.

Des évolutions suivies de près par la Commission nationale informatique et liberté (CNIL)

En France, la CNIL a commencé à se saisir des problématiques des données collectés sur des objets connectés dans le secteur des réseaux de distribution d'électricité intelligents (les « smarts grids »7 ). Elles préfigurent les obligations des opérateurs vis-à-vis des clients en leur qualité de citoyen.

La CNIL pose un constat : le caractère « intelligent » attendu des projets de ville numérique provient des données captées par les objets connectés : ce ne sont pas les villes qui deviennent intelligentes, mais ce sont leurs données. Ces données, souvent présentées comme anonymes, ne le sont pas toujours, d'autant plus que les techniques de ré-identification de données évoluent sans cesse. Par exemple, un capteur de présence qui pilote l'éclairage public d'une rue peu passante peut permettre de deviner quel riverain est passé, si la temporisation d'extinction des lampadaires est toujours la même.

Ces compteurs communicants suscitent des questions nouvelles en matière de vie privée. Une analyse approfondie des courbes de charge 8 pourrait permettre de déduire un grand nombre d'informations sur les habitudes de vie des occupants d'une habitation : heures de lever et de coucher, heures ou périodes d'absence, présence d'invités dans un logement, prises de douche, nombre de personnes présentes dans le logement, etc. De manière plus globale, la gestion des données, collectées dans le logement et transmises à l'extérieur pour permettre un pilotage à distance de certains équipements domestiques, va élargir le champ des investigations à venir dans le domaine de la police judiciaire. Les locaux à usage professionnel seront interconnectés avec leur environnement média et le reste de la sphère publique. Ces ensembles de « béton intelligent », par leur capacité à réagir aux besoins de leur environnement, garantissent une traçabilité des opérations accomplies. Ils sont aussi en mesure de faire face à toute tentative d'atteinte à leur intégrité comme des actes de malveillance physique ou des cyberattaques. L'efficience de la sûreté et de la sécurité apportées par ces nouvelles technologies devra néanmoins prendre en compte les principes fondamentaux du droit des personnes reconnus dans les sociétés démocratiques, tant dans leur sphère intime que professionnelle.

Ces masses de données à caractère personnel ou public soulèvent d'ores et déjà une nouvelle réflexion sur la recevabilité de la preuve fondée en droit français sur le principe de loyauté et dans son prolongement, le principe d'égalité des armes, principe que la Cour européenne des droits de l'Homme applique avec vigilance. Les nouveaux modes d'investigation ouvrent des perspectives dans la manifestation de la vérité des enquêtes criminelles et délictuelles.

Les process pour assurer la sécurité des personnes et des biens vont se trouver profondément changés par l'implantation de capteurs de données dans les espaces publics comme privés. La connaissance et l'accès des données recueillies devraient, dans la limite des libertés fondamentales et sous le contrôle du juge, être prises en compte dans l'analyse et la lutte contre les phénomènes de délinquance d'une circonscription. Les normes de résilience des espaces connectés et l'efficience dans l'analyse des mégadonnées (Big data) dessinent pour le futur les outils d'aide à la décision des politiques publiques de sécurité.

  8 http://www.cnil.fr/documentation/deliberations/deliberation/accessible/non/delib/279/ Mes remerciements vont à Maître Alain Bensoussan, avocat spécialisé dans le Droit des technologies avancées qui a bien voulu m'apporter son expertise dans la rédaction de cette note. http://www.alain-bensoussan.com/ page 4 Note n° 8 du CREOGN Rédacteur : chef d'escadron Jérôme LAGASSE

http://www.insee.fr/fr/methodes/default.asp?page=definitions/ville.htm Note numéro 8 décembre

Villes intelligentes et Normes de qualité : Impacts sur les politiques publiques de sécurité

Khaled Sherbini, Robert Krawczyk, Overview of intelligent architecture : 1st ASCAAD International Conference, e-design in ArchitectureKFUPM, Dhahran, Saudi Arabia, 12-2004

http://www.assystem.com/fr/entreprise/livre-blanc-introduction.html

http://www.cnil.fr/documentation/fiches-pratiques/fiche/article/biometrie-des-dispositifs-sensibles-soumis-a-autorisation-de-la-cnil/ page 2 Note n° 8 du CREOGN Rédacteur : chef d'escadron Jérôme LAGASSE

G29 : groupe des autorités européennes de protection des données personnelles

Pour des applications concrètes : http://intellistreets.com/index.php

http://www.cnil.fr/linstitution/actualite/article/article/compteurs-communicants-premieres-recommandations-de-la-cnil/ page 3 Note n°

du CREOGN Rédacteur : chef d'escadron Jérôme LAGASSE