Yunchao Ma

Xiaozhou Liu

Xinyu Guan

Hui Li

Yusran Yusran

Ming Xue

Qianrong Fang
email: qrfang@jlu.edu.cn

Yushan Yan

Shilun Qiu

Valentin Valtchev
email: valentin.valtchev@ensicaen.fr

M P Mukherjee

E L Levendorf

V B Spitler

M G Shields

Spencer

Z B Zhuang

S Gu

R B Kaspar

J Zheng

S P Biswal

V Kandambeth

G Venkatesh

M Kaur

T Addicoat

S Heine

S Diercks

N Lin

E A Kornienko

E Kapustin

One-Pot Cascade Syntheses of Microporous and Mesoporous Pyrazine-Linked Covalent Organic Frameworks as Lewis-Acid Catalysts

Covalent organic frameworks (COFs) are crystalline porous solids with broad potential applications. So far, the successful construction of COFs was limited to a few condensation reactions, and nearly all COFs were obtained by single-step synthesis based on predesigned linkers. Here, we report a general strategy in view of a one-pot cascade reaction to prepare both microporous and mesoporous fully π-conjugated pyrazine-linked COF materials (PZ-COFs). The obtained PZ-COFs show high chemical stability, large specific surface areas as well as H2, CH4 and CO2 uptake capacities. Furthermore, we demonstrate that manganese(II)-incorporated PZ-COFs can act as excellent Lewis-acid catalysts for the cyanosilylation of aromatic aldehydes. This study not only provides a facile method to synthesize COFs required for multistep reactions but also expands the applications of COFs as promising catalysts.

Introduction

As a new class of crystalline porous polymers, covalent organic frameworks (COFs) [1] have attracted considerable attention due to their outstanding potential in gas adsorption and separation, [2] proton conduction, [3] optoelectronics, [4] drug deliver, [5] chemical sensing, [6] and especially heterogenous catalysis. [7] Since the pioneering work of Yaghi in 2005, [1a] a variety of two-dimensional (2D) COFs [8] with eclipsed or staggered structures and three-dimensional (3D) COFs with the ctn, [9] bor, [10] dia [11] or pts [12] topology have been prepared

over the past decade. However, owing to the complex nature of reversible synthesis, successful methods for the constructions of COF materials have been limited to a few chemical reactions, including three most commonly used types: boronic acid trimerization, boronate ester formation, and Schiff base reaction. [1c,1d] Furthermore, nearly all COFs reported were obtained by single-step reaction based on predesigned linkers. As we all known, to obtain pure predesigned linkers is general difficulty, and thus the exploration of new synthetic strategies, for example, obtaining linkers at the same time in synthesis of COFs, is an important and crucial task for the development of this promising class of porous materials.

Herein we report a new synthetic approach based on a one-pot cascade reaction strategy to produce COF materials. In view of this synthetic method, two microporous and mesoporous pyrazine-linked COFs, denoted PZ-COF-1 and PZ-COF-2, were successfully obtained by one-pot synthesis involving a two-step dehydration-oxidation reaction. Both materials show high chemical stability, impressive specific surface area, and promising gas storage capacities for H 2 , CH 4 and CO 2 . Furthermore, we demonstrate that PZ-COFs can incorporate manganese(II) ions by coordinating to nitrogen atoms of adjacent layers in PZ-COFs, and the resulting Mn(II)assembled COF materials can act as excellent Lewis-acid catalysts for the cyanosilylation of aldehyde compounds.

Results and discussion

Our strategy for preparing PZ-COFs involves a one-pot dehydration and oxidation cascade reaction. As shown in Scheme 1a and 1b, 9,10-diazaanthracene (DAA) can be normally produced by the two-step path of the combination of both dehydration and oxidation reaction, which is a complicated process.

[13] Thus, we design the dehydration and oxidation cascade reaction to obtain DAA by one-pot synthesis of 1,2-diaminobenzene (DAB) and 1,2-dihydroxybenzene (DHB, Scheme 1c and Figure S1 in SI). On the basis of the same strategy, DHB is replaced by a flat triangular linker, hexahydroxy triphenylene (HHTP) and the DAB is substituted

Please do not adjust margins

Please do not adjust margins by linkers with four amine groups, 1,2,4,5-tetraminobenzene (TAB) or 3,3′-diaminobenzidine (DABZ), yielding two new largepore structures. These new COFs, denoted PZ-COF-1 and PZ-COF-2 exhibit pore diameter of 18 Å and 25 Å, respectively (Scheme 1d). In this case, HHTP can be defined as a 3connected node, and TAB or DABZ can act as a 2-connected node, which results in 2D structures with the boron nitride net (bnn, Scheme 1e).

[14]

The syntheses of PZ-COFs were carried out by solvothermal reaction of HHTP, K 2 Cr 2 O 7 and TAB or DABZ in a mixed solution of N-methyl-2-pyrrolidone (NMP), mesitylene and acetic acid (AcOH), followed by heating at 120 °C for 3 days. The AcOH is employed as a catalyst to promote the dehydration reaction and K 2 Cr 2 O 7 is an oxidizer for the oxidation reaction. The conversion of the reactants was 85% for PZ-COF-1 and 83% for PZ-COF-2. The products, black solids, were insoluble in common organic solvents such as tetrahydrofuran (THF), acetone, methanol (MeOH), dichloromethane (CH 2 Cl 2 ), chloroform (CHCl 3 ), hexane, N,Ndimethylformamide (DMF), dimethylsulfoxide (DMSO) and dioxane.

ARTICLE

Please do not adjust margins Please do not adjust margins HHTP), and the N-H stretching band (around 2952 cm -1 for TAB and 3388 cm -1 for DAB), indicating a completed conversion of these groups. Meanwhile, the characteristic stretching bands of pyrazine linkages (1256 and 1448 cm -1 for PZ-COF-1 as well as 1265 and 1448 cm -1 for PZ-COF-2) emerged in the IR spectra.

[8i] The atomic order of PZ-COFs was further studied by solid-state 13 C cross-polarization magic-angle-spinning (CP/MAS) NMR spectroscopy (Figures S9 and S10 The crystalline nature of new PZ-COFs was confirmed by PXRD analysis (Figure 1). After a geometrical energy minimization by using the Materials Studio Software package [15] In addition, the full profile pattern matching (Pawley) refinements are performed from the experimental PXRD patterns. PXRD peaks at 4.05, 7.01, 8.10, 10.72 and 25.87° for PZ-COF-1 can be assigned to the (100), ( 110), ( 200), ( 210) and (001) Bragg peaks. The peaks at 3.18, 5.53, 6.39, 8.45 and 25.89° for PZ-COF-2 correspond to the (100), ( 110), ( 200), ( 210) and ( 001 The specific surface area and porosity of PZ-COFs were determined by measuring N 2 adsorption at 77 K. As can be seen in Figure 3, PZ-COF-1 exhibited the characteristic for Please do not adjust margins Please do not adjust margins microporous materials type I isotherm with sharp uptake below 0.05 P/P 0 . Type IV isotherm with a two-stmeep uptake below 0.2 P/P 0 , which is typical of ordered mesoporous materials, was recorded for PZ-COF-2. The absence of hysteresis during desorption for PZ-COF-2 is a common feature of materials containing hexagonally aligned 1D mesopores.

[16]

The application of the Brunauer-Emmett-Teller (BET) model in the low pressure region (0.005 < P/P 0 < 0.105) showed a BET surface areas of 845 m 2 g -1 for PZ-COF-1 and 1130 m 2 g -1 for PZ-COF-2 (Figures S20 and S21 in SI). The pore-size distributions of PZ-COFs were calculated by nonlocal density functional theory (NLDFT) and showed a narrow pore width (16 Å for PZ-COF-1 and 24 Å for PZ-COF-2, Figure 3 inset), which was in good agreement with the pore sizes predicted from their crystal structures (18 Å for PZ-COF-1 and 25 Å for PZ-COF-2). In addition the adsorption of H 2 , CO 2 and CH 4 for both PZ-COFs was studied in order to evaluate their potential application in gas storage (Figures S22-24 in SI). PZ-COF-1 showed uptake of 121 cm 3 g -1 of H 2 , 68 cm 3 g -1 of CO 2 and 14 cm 3 g -1 of CH 4 . The mesoporous PZ-COF-2 could store up to 156 cm 3 g -1 of H 2 , 91 cm 3 g -1 of CO 2 and 21 cm 3 g -1 of CH 4 .

Scheme 2

Schematic representation for the syntheses of Mn/PZ-COFs.

Encouraged by high porosity and the appropriate distance (~3.4 Å) of eclipsed nitrogen atoms in adjacent layers, which makes PZ-COFs an ideal scaffold for incorporating metal ions, [7a] we successfully assembled the manganese(II)coordinated COF materials (denoted as Mn/PZ-COFs), and explored their catalytic potential for the cyanosilylation of aldehyde compounds. Typically, through a simple posttreatment of PZ-COFs with manganese acetate, Mn(OAc) 2 , Mn/PZ-COFs were facilely prepared (Scheme 2 and see SI for details). A comparison of PXRD patterns of PZ-COFs and Mn/PZ-COFs revealed that crystal structures of PZ-COFs were well preserved after the treatment with Mn(OAc) 2 (Figures S25 and S26 in SI). SEM images suggested that layer structures of PZ-COFs also remained unchanged after the reaction with Mn(OAc) 2 (Figures S27 and S28 in SI). The well-dispersed manganese species could be clearly observed in the energy dispersive X-ray (EDX) mapping analysis (Figures S29 and S30 in SI). Nitrogen adsorption isotherms at 77 K of Mn/PZ-COFs indicated a lower N 2 adsorption which is due to the presence of Mn(OAc) 2 in the pores (Figures S31 and S32 in SI). Manganese content of 6.3 wt% for Mn/PZ-COF-1 and 6.6 wt% for Mn/PZ-COF-2 was determined by ICP analysis. X-ray photoelectron spectroscopy (XPS, Figure S33 in SI) showed that the binding energies of Mn 2p 3/2 in Mn/PZ-COFs were about 642 eV, indicating that the Mn species were in +2 state. Mn/PZ-COFs and a model complex Mn/Phen (Phen = 1,10phenanthroline) had a similar shift of 1 eV in comparison with that of free Mn(OAc) 2 , which suggested that Mn ions were most probably located in between the adjacent layers of PZ-COFs and efficiently coordinated with two nitrogen atoms from different layers.

[7a] The catalytic activities of Mn/PZ-COFs were subsequently examined in one of the representative Mn(II)-catalyzed reactions, i.e., the cyanosilylation reaction, which is an important step to key derivatives in the syntheses of fine chemicals and pharmaceuticals. [17] The catalytic reactions were performed with 1.0 mmol of each reactant in dry CH 2 Cl 2 (6.0 mL) with PZ-COF-1 or PZ-COF-2 (10 mol%) at room temperature for 5~6 h. The conversion and the product distribution were monitored by 1 H NMR spectroscopy based on the starting materials. As shown in Table 1, Me 3 SiCN reacted with benzaldehyde to form the product α-(trimethylsilyloxy)phenylacetonitrile (Ar = phenyl) in excellent yields (98% for Mn/PZ-COF-1 and 99% for Mn/PZ-COF-2). Furthermore, by replacing benzaldehyde reactant with 4biphenylcarboxaldehyde, 1-naphthaldehyde, 4methoxybenzaldehyde or 4-nitrobenzaldehyde, and keeping all other conditions the same, high yields (96-99%) can be obtained under different reaction time (3-8 hrs, Table 1). Figures 4, S34 and S35 depict the concentration of products as a function of time. We verified that the reaction was indeed catalyzed by Mn/PZ-COFs instead of free Mn(OAc) 2 by a control experiment, in which the catalyst was removed from the reaction mixture after 1 h, and the isolated solution was Please do not adjust margins Please do not adjust margins retained under the same reaction conditions. No further conversion was observed in this case (Figure S36 in SI). After the catalytic reactions, the results of PXRD confirmed the structural integrity of Mn/PZ-COFs, thus revealing the high stability of new COF materials in the cyanosilylation reaction (Figures S37 and S38 in SI). The COF crystals can be easily isolated from the reaction mixture by a simple filtration and reused at least four times with almost no loss of activity and similar TOF (Figures S39 and S40 in SI).

Conclusions

In conclusion, we have developed a new synthetic strategy to construct COF materials by employing one-pot dehydration and oxidation cascade reactions. Two novel 2D COFs, microporous PZ-COF-1 and mesoporous PZ-COF-2, were prepared. These new materials showed high chemical stability, large specific surface areas as well as promising H 2 , CH 4 and CO 2 uptake capacities. In addition, we explored the incorporation of Mn(II) in PZ-COFs and found that manganesecoordinated COFs can act as excellent Lewis-acid catalysts. One-pot cascade synthesis for COF materials exemplified in this work may not only expand the development of COFs with innovative synthesis strategy, but also promote the applications of functional COFs.

Fig. 1

 1 Fig. 1 PXRD patterns of PZ-COF-1 (a) and PZ-COF-2 (b) with the observed profile in black, refined in red, the difference (observed minus refined) in pink, and calculated based on the eclipsed structure in blue. Inset: enlarged experimental PXRD patterns and SEM images.

  in SI). The two signals at δ = 125 and 134 ppm for PZ-COF-1 and at δ = 124 and 133 ppm for PZ-COF-2 can be assigned to different aromatic carbons, respectively. According to the thermogravimetric analysis (TGA), the PZ-COFs are stable up to about 300 °C (Figure S11 in SI). We also tested the chemical stability of PZ-COFs by dispersing the samples in aqueous HCl (1 M) or NaOH (1 M) solutions and found that there was no change in their powder X-ray diffraction (PXRD) patterns (Figures S12 and S13 in SI).

Fig. 2

 2 Fig. 2 Structural representations of microporous PZ-COF-1 (a) and mesoporous PZ-COF-2 (b). C, yellow; N, blue; H, white.

  based on the eclipsed structure the unit cell parameters were determined. PZ-COF-1 exhibits space group P6/mmm (No. 191) with unit cell of a = b = 25.184 Å, c = 3.439 Å, α = β = 90°, and γ = 120°. PZ-COF-2 shows space group P6/m (No. 175) with unit cell of a = b = 32.009 Å, c = 3.440 Å, α = β = 90°, and γ = 120°. Simulated PXRD patterns show good match with the experimental ones (Figure 1, black and blue curves).

  ) Bragg peaks, respectively. The refinement results revealed unit cell parameters nearly equivalent to the predictions with excellent agreement factors (a = b = 25.761 Å, c = 3.555 Å, α = β = 90°, γ = 120°, wR p = 1.72%, and R p = 0.69% for PZ-COF-1; a = b = 32.521 Å, c = 3.532 Å, α = β = 90°, γ = 120°, wR p = 1.91%, and R p = 0.89% for PZ-COF-2). Besides the eclipsed structure, we also considered an alternative staggered model, which was set up from the space groups of P6 3 /mmc (No. 194) for PZ-COF-1 or P6 3 /m (No. 176) for PZ-COF-2. However, these calculated patterns did not match the experimental PXRD patterns (Figures S14-19 and TablesS1-4in SI). On the basis of the above results, we can state that both PZ-COFs have the expected architectures with the eclipsed model, which show the microporous hexagonal pores with diameter of about 18 Å for PZ-COF-1 and mesoporous channels with diameter of about 25 Å for PZ-COF-2 (Figure2).

Fig. 3

 3 Fig. 3 N 2 adsorption-desorption isotherms of microporous PZ-COF-1 (a) and mesoporous PZ-COF-2 (b) at 77 K. Inset: the pore size distribution.

a

  Reaction conditions: Me 3 SiCN (1.0 mmol), aldehyde (1.0 mmol), dry CH 2 Cl 2 (6.0 mL), Mn/PZ-COF-1 or Mn/PZ-COF-2 (0.1 mmol), room temperature, under Ar.

Fig. 4

 4 Fig. 4 Concentration (%) versus time (h) for the cyanosilylation of benzaldehyde (blue), 4-biphenylcarboxaldehyde (red), and 1-naphthaldehyde (black) on Mn/PZ-COF-1 (a) and Mn/PZ-COF-2 (b). Inset: the structures of products. C, green; N, blue; O, red; Si, pink. H atoms are not shown for clarity.

Table 1

 1 Catalytic activities of Mn/PZ-COFs in the cyanosilylation of aldehyde compounds

	a

Acknowledgements

This work was supported by National Natural Science Foundation of China (21571079, 21621001, 21390394, 21571076, and 21571078), "111" project (B07016 and B17020), Guangdong Science and Technology Department Project (2012D0501990028) , and the program for JLU Science and Technology Innovative Research Team. Q.F and V.V. acknowledge the support from Thousand Talents program (China). V.V., Q.F. and S.Q. acknowledge the collaboration in the framework of China-French joint laboratory Zeolites.


Zhi-Tao Wang

Valentin Valtchev

Qian-Rong Fang

Xiu-Mei Li

Ya-Ru Pan

Prof Mei Xiu-

Li

Hydrothermal Synthesis and Crystal Structure of Three-dimensional Supramolecular Zinc, Manganese Coordination Polymers

Keywords: hydrothermal synthesis, crystal structure, Zn

Two new complexes [Zn2(pzdc)(L)2(H2O)]2n• 2nH2O (1) and [Mn(µ2-O)(H2O)2-(HL)]2n• 2nNIPH (2) (H2pzdc = pyrazine-2,3-dicarboxylic acid, HL = 3-(2-Pyridyl) pyrazole, H2NIPH = 5-nitroisophthalic acid) have been hydrothermally synthesized and structurally characterized by elemental analysis, IR spectrum, UV spectrum, TG, fluorescence spectrum and single-crystal X-ray diffraction. Complex 1 shows two-dimensional (2D) network, which was stabilized by O-H• • • O, C-H• • • O hydrogen bonding and π-π interactions and extended into 3D supramolecular architecture. Complex 2 is zero-dimensional structure, which was further extended into 3D supramolecular framework through N-H• • • O, O-H• • • O, C-H• • • O hydrogen bonds and π-π interactions.

Introduction

The design and synthesis of metal-organic coordination polymers relied on the selection of ligands and metal ions has become a very attractive research field. This is motivated not only by the intriguing structural diversity but also by the demand of applying functional materials into the fields of catalysis, porosity, magnetism, luminescence and nonlinear optics. [START_REF] Uppadine | Three-level synthetic strategy towards mixed-valence and heterometallic [2×2] gridlike arrays[END_REF][2][3] In general, grids with various sizes and shapes can be synthesized by choosing suitable single metal ions and organic ligands such as carboxylates and N-donor groups. [START_REF] Hines | Exploring control of cadmium halide coordination polymers via control of cadmium(II) coordination sites utilizing short multidentate ligands[END_REF][5][6] Self-assembly is a complex process, highly influenced by many factors, such as the coordination geometry of metal ions, the nature of organic ligands, solvent system, temperature, pH value of the solution, the ratio between metal salt and ligand, the templates and the counter anions. [START_REF] Hong | A silver(I) coordination polymer chain containing nanosized tubes with anionic and solvent molecule guests[END_REF][START_REF] Hong | A nanometer-sized metallosupramolecular cube with Oh symmetry[END_REF][9][10][START_REF] Noro | Framework engineering by anions and porous functionalities of Cu(II)/4,4'-bpy coordination polymers[END_REF][12][START_REF] Kasai | Flexible coordination networks with fluorinated backbones. Remarkable ability for induced-fit enclathration of organic molecules[END_REF][START_REF] Du | Proton-controlled inter-conversion between an achiral discrete molecular square and a chiral interpenetrated doublechain architecture[END_REF] Except for these factors, other forces such as hydrogen-bonding, π-π interactions, metal-metal interactions can also greatly influence the supramolecular topology and its dimensionality. [START_REF] Li | Synthesis, crystal structure and theoretical calculations of a copper(II) coordination polymer assembled by 4,4'-oxydibenzoic acid and 1,4-bis(Imidazol-1-ylmethyl)-benzene ligands[END_REF][START_REF] Pan | Hydrothermal syntheses and crystal structures of two complexes of cobalt and manganese assembled by 4,4΄-oxydibenzoic acid[END_REF][START_REF] Liu | Syntheses and characterization of six coordination polymers of zinc(II) and cobalt(II) with 1,3,5-benzenetricarboxylate anion and bis(imidazole) ligands[END_REF] Therefore, these considerations made us investigate new coordination structures with pyrazine-2,3-dicarboxylic acid (H2pzdc), 5-nitroisophthalic acid (H2NIPH) and chelating ligands. In this manuscript, we reported the syntheses, crystal structures, IR, UV,

X-ray crystallographic

Single-crystal X-ray diffraction data for 1 and 2 were measured on a Bruker Smart Apex II CCD diffractometer with graphite-monochromated Mo Kα radiation (λ = 0.71073 Å) at 293 K. The structure was solved with the direct method of SHELXS-97 and refined with full-matrix least-squares techniques using the SHELXL-97 program. [START_REF] Sheldrick | Programs for X-ray Crystal Structure Solution[END_REF][START_REF] Sheldrick | Programs for X-ray Crystal Structure Refinement[END_REF] Anisotropic thermal parameters were assigned to all non-hydrogen atoms. The hydrogen atoms were placed at the calculated positions and refined as riding atoms with isotropic displacement parameters. Crystallographic parameters and the data collection statistics for structure 1 and 2 are listed in Table 1. Selected bond lengths and bond angles are shown in Table 2. Further crystallographic parameters have been deposited with the Cambridge Crystallographic Data Centre (no. 1468826 (1), 1439401 (2); deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk/data_request/cif).

Results and discussion

IR Spectrum

Complex 1: Two bands at 1637 and 1357 cm -1 can be attributed to (v(OCO)assym) and

(v(OCO)sym), [START_REF] Devereux | Synthesis, X-ray crystal structures and biomimetic and anticancer activities of novel copper(II)benzoate complexes incorporating 2-(4′-thiazolyl)benzimidazole (thiabendazole), 2-(2-pyridyl) benzimidazole and 1,10-phenanthroline as chelating nitrogen donor ligands[END_REF] respectively. The Δν (ν(OCO)assym -ν(OCO)sym) is 280 cm -1 (>200), exhibiting the presence of monodentate linkage of carboxylates in the dianions. Therefore the carboxylates coordinate to the metal as monodentate ligands via the carboxylate groups. [START_REF] Farrugia | Windows Program for Crystal Structure Analysis[END_REF] The absence of the characteristic bands at abound 1700 cm -1 in complex 1

were owing to the protonated carboxylic group indicates that the complete deprotonation of pzdc ligand upon reaction with Zn ions. [START_REF] Fu | The structure and fluorescence properties of two novel mixed-ligand supramolecular frameworks with different structural motifs[END_REF] Moreover, X-ray diffraction analysis further attributes the existence of monodentate coordination manners of the carboxylate groups and prence deprotonation of pzdc ligands.

Complex 2: Infrared spectroscopy of complex 2 shows the typical anti-symmetric (1606 cm -1 ) and symmetric (1334 cm -1 ) stretching bands of carboxylate groups. The absence of the characteristic band around 1700 cm -1 in complex 2 owing to the protonated carboxylic group indicates that the present deprotonation of NIPH ligand. Moreover, the strong and broad band centered at 3413 cm -1 for 2 is owing to the H-O-H stretching vibration of water molecule in the light of the known structure. [START_REF] Nakamoto | Infrared Spectra and Raman Spectra of Inorganic and Coordination Compound[END_REF] In the crystal structure of complex 1, the HL ligands take µ3 coordination mode and the completely deprotonated pzdc ligands show one kind of coordination mode, namely, monodentate bridging mode. As a result, two Zn(II) ions are linked by four HL ligand to form dinuclear subunits, which are bridged by pzdc ligands to yield a two-dimensional (2D) network architecture (Fig. 2). Each Zn(II) shows a distorted square-pyramidal coordination structure.

It is worth noting that hydrogen bonding interactions are important in the synthesis of supramolecular architecture. [START_REF] Krische | [END_REF] There are existent in O-

H• • • O and C-H• • • O hydrogen
bonding interactions between carboxylate oxygen atom, carbon atoms and coordinated water molecules in complex 1 (Table 3). In addition, there are π-π interactions (Fig.

Table 3. Hydrogen bonds for complex 1 and 2

Complex 2 crystallizes in the triclinic system, space group P-1 and features a zero-dimensional structure. The coordination environment of Mn(II) in 2 is displayed in Fig. 4. There are two Mn(II) ion, two NIPH ligand, two HL ligand, four coordinated water 3). Moreover, In complex 2, 5-member ring of HL and 6-member ring of NIPH ligand centroid distances are 3.6879(10) Å for 1) and C( 9)C( 10)C( 11)C( 12)C( 13) C( 14) rings (x, y, z), with the vertical distance to be 3.2664(7) Å, indicating the existence of π-π effect, so that the structure is more stable. Therefore, a three-dimensional supramolecular network structure is formed by such hydrogen bonds and π-π stacking (Fig. 5).

D-H•••A d(D-H) d(H•••A) d(D•••A) ∠(DHA) 1 O(5)-H(5A)• • • O(3) 0.
N(1)N(2)C(3)C(2)C(
In order to check the purity of polymer 1 and 2, powder X-ray diffraction of the as-synthesized sample were measured at room temperature (Fig. S1). The peak positions of experimental patterns are in good agreement with the simulated ones, which clearly indicates good purity of 1 and 2. [START_REF] Gilbert | Essentials of Molecular Photochemistry[END_REF][START_REF] Han | Hydrothermal syntheses, crystal structures and magnetic properties of two copper(II) complexes involved in situ ligand synthesis[END_REF] Thermal analysis

The thermal stability of complex 1 was tested in the range of 50~700 ℃ under a nitrogen atmosphere at a heating rate of 5 ℃• min -1 . The TGA curve of complex 1 is shown in Fig. S2.

It

Photoluminescent properties

The emission spectrum of complex 1 in the solid state at room temperature is displayed in Fig. 6. It can be reviewed that complex 1 shows blue photoluminescence with an emission maximum at ca. 460 nm upon excitation at 375 nm. By way of studying the nature of these emission bands, we first investigated the photoluminescence properties of free pyrazine-2,3-dicarboxylic acid, and indicated that it does not emit any luminescence in the range of 400~800 nm. And then we discussed the emission spectrum of HL itself and the result confirmed that it does not emit any luminescence in the range 400~800 nm, which has also been proved previously. [START_REF] Rendell | Fluorescence and Phosphorescence[END_REF] Therefore, on the basis of previous literature, [START_REF] Zheng | Recent advances in luminescent monomeric, multinuclear, and polymeric Zn(II) and Cd(II) coordination complexes[END_REF] the emission band could be assigned to the emission of ligand-to-metal charge transfer (LMCT). For possessing strong fluorescent intensity, it appears to be good candidates for novel hybrid inorganic-organic photoactive materials.

UV Spectrum Analysis

The UV spectra for complex 2 (Fig. 7), H2NIPH and HL ligands have been studied in the solid state. For H2NIPH and HL ligands, there are 277 and 245 nm absorption bands, respectively, while 275 nm for complex 2, which should be assigned to the n→π* [START_REF] Mohamed | Synthesis, investigation and spectroscopic characterization of piroxicam ternary complexes of Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with glycine and DL-phenylalanine[END_REF][START_REF] Dong | Seven copper coordination polymers based on 5-iodo-isophthalic acid: halogen-related Bonding and N-donor auxiliary ligands modulating effect[END_REF][START_REF] Glasson | New nickel(II) and iron(II) helicates and tetrahedra derived from expanded quaterpyridines[END_REF][START_REF] Pandey | ) and copper(II)[END_REF] transition of HL ligand in 2. However, upon ligand coordination to Mn 2+ ion, the absorption intensity increases.

Conclusions

In general, we have described two new supramolecular zinc, manganese coordination polymers. In 1, the pyrazine-

Figure 1 .

 1 Figure 1. The coordination environment of the Zn(II) center in 1. Symmetry

Figure 2 .

 2 Figure 2. View of the two-dimensional network along a axis (Carbon atoms

) in complex 1

 1 between pyrazine ring of pzdc ligand and pyrazole ring of HL ligand. The centroid-to-centroid distance between adjacent ring is 3.456(2) Å for N(4)N(5)C(14)C(13)C(12) and N(1)C(3)C(4)N(2)C(5)C(6) (x, y, z) rings. The perpendicular distance is 3.1530(15) Å for N(4)N(5)C(14)C(13)C(12) and N(1)C(3)C(4)N(2)C(5)C(6) (x, y, z) rings. Thus, the two-dimensional networks are further extended into a three-dimensional supramolecular framework through hydrogen bonds and π-π interactions, which play an important role in stabilizing compound 1.

  molecule and two µ2-O atoms in the molecular structure. Each Mn(II) ion is six-coordinated by two coordinated water molecules (O(7), O(9)), two µ2-O atoms (O(8), O(8A)) and two nitrogen donors (N(2) and N(3)) from HL ligand to supply a distorted octahedral coordination structure. One coordinated water molecule (O(9)), one µ2-O atom (O(8)) and two nitrogen atoms (N(2), N(3)) define an equatorial plane, whereas the axial coordination sites are employed by the other coordinated water molecule (O(7)) and µ2-O atom (O(8A)). The Mn-O distances fall in the range of 2.1346(14)~2.3336(14) Å, and Mn-N bond length fall in the 2.2264(14)~2.2556(14) Å, which are all in the normal range and the coordination angles around Mn(II) ion are in the range of 73.95(5)º ~168.77(5)º .In 2, the HL ligand adopts classic chelating mode, while NIPH ligand was not involved in coordination, which just play a role of balance charge. Two Mn(II) ions are linked by two µ2-O atoms to form dinuclear subunits, and exhibits zero-dimensional structure.Further study of the crystal packing of complex 2 suggests that there are three kinds of N-H• • • O, O-H• • • O and C-H• • • O hydrogen bonding interactions between nitrogen atom of HL ligand, carboxylate oxygen atoms of NIPH ligand, coordinated water molecule and carbon atoms of HL and NIPH ligands (Table

  displays that the first weight loss of 49.5% from 60 to 192 ℃ corresponds to the release of water molecules and HL ligand (calcd:50.0%). Upon further heating, an obvious weight loss (26.2%) occurs in the temperature range of 192~525 ℃ , corresponding to the removal of pzdc ligands (calcd: 27.1%). After 525 ℃ no weight loss is found, which indicates the complete decomposition of 1.

Figure 3 .

 3 Figure 3. A view of p-p stacking interactions in complex 1.

Figure 4 .

 4 Figure 4. The molecular structure of complex 2. Symmetry codes: A: -x-1, -yt2, -z.

Figure 5 .

 5 Figure 5. View of the 3D supramolecular architecture of 2 formed by

Figure 6 .

 6 Figure 6. Solid-state emission spectrum of 1 at room temperature.

Figure 7 .

 7 Figure 7. The UV spectrum of 2 at room temperature.

Figure captions:Fig. 1 .

 1 Figure captions:

Fig. 2 .

 2 Fig. 2. View of the two-dimensional network along a axis (Carbon atoms and one

Fig. 3 . 1 Fig. 4 .

 314 Fig. 3. A view of π-π stacking interactions in complex 1

Fig. 5 .

 5 Fig. 5. View of the 3D supramolecular architecture of 2 formed by hydrogen-bonding

Fig. 6 .Fig. 7 .

 67 Fig. 6. Solid-state emission spectrum of 1 at room temperature

Table 1 .

 1 Crystallographic parameters and summary of data collection for 1 and 2

	Parameter	Complex 1	Complex 2
	Empirical formula	C44H32 N16O11Zn4	C32H30Mn2N8O18
	Fw (g/mol)	1222.34	924.52
	Crystal system	Monoclinic	Triclinic
	Space group	C2/c	P-1
	a [Å ]	29.465(2)	7.5193(5)
	b [Å ]	12.4103(8)	10.7808(6)
	c [Å ]	14.7059(9)	11.4968(7)
	α [ ˚ ]	90.00	88.3880(10)
	β [ ˚ ]	117.727(2)	86.9260(10)
	γ [ ˚ ]	90.00	85.5920(10)
	Volume [Å 3 ]	4760.1(6)	927.61(10)
	Z	8	1
	Dc(g/cm 3 )	1.706	1.655
	GOF	1.014	1.110
	Reflns collected/unique 4206/3233	3611/3382
	Rint	0.0491	0.0100
	R1 [I>2σ(I)]	0.0333	0.0291

Table 2 .

 2 Selected bond lengths (Å) and bond angles (deg) for 1 and 2

	1

  2,3-dicarboxylate ligands function in monodentate bridging coordination mode, the HL ligands take µ3 coordination mode. As a result, two Zn(II) ions are linked by four HL ligand to yield dinuclear subunits, which are bridged by pzdc ligands to form a two-dimensional network structure. In 2, the HL ligand takes classic chelating mode, while NIPH ligand was not involved in coordination, which just play a role of balance charge. Two Mn(II) ions are linked by two µ2-O atoms to form dinuclear subunits, and exhibits zero-dimensional structure. It is worthy to note that the intermolecular hydrogen bonds and π-π interactions play an important role in the supramolecular structure and extended complex 1 and 2 into 3D supramolecular framework. complexes of a hexadentate pyridine amide ligand. Effect of donor atom (ethervs. thioether) on coordination geometry, spin-state of cobalt and MIII-MII redox potential. Dalton Trans. 2011, 40, 10758-10768.

Table 1 .

 1 Crystallographic parameters and summary of data collection for 1 and 2

Table 2 .

 2 Selected bond lengths (Å) and bond angles (deg) for 1 and 2

Table 3 .

 3 Hydrogen bonds for complex 1 and 2

Acknowledgments

This work was supported by the Science and Technology Development Project of Jilin Provincial Science & Technology Department (201205080) and the Science and Technology Research Projects of the Education Department of Jilin Province (2013.384). Program supports from State Key Laboratory of Theoretical and Computational Chemistry of Tonghua Normal University are gratefully acknowledged.

Supporting information:


Adrien Barton
email: adrien.barton@irit.fr

Fumiaki Toyoshima
email: fumiaki.toyoshima@usherbrooke.ca

Jean-François Ethier
email: ethierj@gmail.com.

Er

Approaching Roles with Affordances

Keywords: Role, affordance, disposition, realizable entity, Basic Formal Ontology Role, affordance, disposition, realizable entity, Basic Formal Ontology (BFO)

We develop an affordance-based approach to a subkind of roles, namely roles that have a causal component and that involve an agent and an environment. This approach is based on a previous dispositional ontology of affordances and effectivities. More specifically, such roles are analyzed as identical to mereological sums of affordances or effectivities when they are realized. We illustrate this theory on the example of the roles of addresser (analyzed as a sum of effectivities when they are realized) and addressee (analyzed as a sum of affordances when they are realized). We discuss the import of this analysis for the category of role in the upper ontology Basic Formal Ontology (BFO), and the relation between this approach and Loebe's tripartition of roles.

Introduction

The world is replete with roles, e.g. students, presidents, lovers, and mothers. Roles are particularly useful for characterizing multifarious entities. For instance, modeling organizations (totally or partially) upon interrelations among roles is nowadays wellestablished [START_REF] Porello | The Ontology of Group Agency[END_REF][START_REF] Wood | Considering Collectives: Roles, Members and Goals[END_REF][START_REF] Ferrario | Organisations and Variable Embodiments[END_REF]. Despite having been the topic of many interdisciplinary investigations, roles still remain nebulous entities, as is indicated by Boella et al.'s [START_REF] Boella | Roles, an interdisciplinary perspective[END_REF] list of open questions about roles, e.g. whether a single definition of roles is possible.

In this paper we will investigate the relationship between roles and affordances along a line of argument that has been proposed by Baldoni et al.'s [START_REF] Baldoni | Modelling the interaction between objects: Roles as affordances[END_REF]. The term "affordance" was coined by Gibson [START_REF] Gibson | The ecological approach to visual perception: classic edition[END_REF] to pin down precisely the interaction between animals and the environment: "The affordances of the environment are what it offers the animal, what it provides or furnishes, either for good or ill" (p. 119). For instance, a gap affords hiding (or being trapped) when it is of a certain size relative to the size of a person, and a stair affords climbing when it is a certain proportion of a person's leg length. As we will explain below, this affordance-based approach to roles captures a key interactional feature of roles [START_REF] Baldoni | Modelling the interaction between objects: Roles as affordances[END_REF]. It has been nonetheless arguably less explored in formal ontology, partly because affordances as such are difficult to analyze from an ontological point of view We will provide below an affordance-based perspective on specific roles 2) that involve an agent and an environment, with recourse to a dispositional ontology of affordances that we have previously developed [START_REF] Toyoshima | Modeling Affordances with Dispositions[END_REF][START_REF] Toyoshima | A formal representation of affordances as reciprocal dispositions[END_REF][START_REF] Toyoshima | Linking image schemas with affordances: An ontological approach[END_REF].

The underlying motivation behind this work lies in part in the category of role in the upper ontology Basic Formal Ontology (BFO) [START_REF] Arp | Building Ontologies with Basic Formal Ontology[END_REF]. The BFO notion of role has been extensively utilized in various domains, ranging from the Ontology of Medically Related Social Entities (OMRSE) [START_REF] Hicks | The ontology of medically related social entities: recent developments[END_REF] in the biomedical domain to BFO-compliant industrial ontologies [START_REF] Smith | A First-Order Logic Formalization of the Industrial Ontology Foundry Signature Using Basic Formal Ontology[END_REF]. Roles in BFO merit further clarification, however. For one thing, there are few in-depth studies (but see [START_REF] Arp | Building Ontologies with Basic Formal Ontology[END_REF][START_REF] Toyoshima | Three Facets of Roles in Foundational Ontologies[END_REF][START_REF] Toyoshima | A Foundational View on Roles in Conceptual Modeling[END_REF][START_REF] Toyoshima | Roles and their siblings in Basic Formal Ontology[END_REF]) on their "realizable" or "potential" nature (to be delineated below) about which many questions and concerns can be raised [START_REF] Guarino | So Far, So Close[END_REF]. As will be detailed below, our affordance-based view of roles can be developed based on the BFO foundational background (against which fruitful results on dispositions have been produced [START_REF] Röhl | Representing dispositions[END_REF][START_REF] Barton | A taxonomy of disposition-parthood[END_REF][START_REF] Barton | The identity of dispositions[END_REF]); and it may also help to elucidate some aspects of the BFO conception of role, and more generally in other upper ontologies.

The remainder of the paper is structured as follows. Section 2 presents the basic structure of BFO (especially its role category) and our theory of dispositions. Taking a cue from Baldoni et al. [START_REF] Baldoni | Modelling the interaction between objects: Roles as affordances[END_REF], Section 3 develops an affordance-based approach to roles by employing our previous dispositional account of affordances. Section 4 is devoted to discussion. Section 5 concludes with some brief remarks on future work.

2.!Preliminaries

2.1.!The Basic Structure of Basic Formal Ontology (BFO)

Our work will be generally anchored to the BFO upper ontology, since we are motivated to clarify the nature of some roles in BFO. Entities fall into two kinds: particulars (written in bold, e.g. John), and classes (written in italic, e.g. Human). We will use standard firstorder logic, formalizing classes as unary predicates.

BFO introduces a top-level division between continuants, which persist across time while having no temporal part; and occurrents (e.g. processes), which extend through time (by having temporal parts). Among continuants are independent continuants (e.g. objects) and dependent continuants. Among the latter, a specifically dependent continuant inheres ("INH") in a specific independent continuant, and thus depend existentially on it: e.g. John's mass massJohn ceases to exist if he does (formally: INH(massJohn, John)).

Dependent continuants can be further divided into qualities and realizable entities. A quality (e.g. mass and shape) is "fully manifested" in its bearer; whereas a realizable entity can be realized in ("REAL") associated processes of specific correlated types in which the bearer participates. BFO presently identifies two immediate subtypes of realizable entities: roles and dispositions, which will be explained below in order.

2.2.!Roles in BFO

A role in BFO is: "a realizable entity that (1) exists because the bearer is in some special physical, social, or institutional set of circumstances in which the bearer does not have to be (optionality), and ( 2) is not such that, if this realizable entity ceases to exist, then the physical make-up of the bearer is thereby changed (external grounding)" ( [START_REF] Arp | Building Ontologies with Basic Formal Ontology[END_REF], pp. 99-100). Examples include: "the role of an instance of a chemical compound to serve as analyte in an experiment, the role of a portion of penicillin to serve as a drug, and the role of a stone in marking a boundary" ( [START_REF] Arp | Building Ontologies with Basic Formal Ontology[END_REF], p. 100). Social roles include, for example, the role of a health professional or the role of a patient.

Because of its ambiguity, we will not use the phrase "play a role", in contrast with its prevalence in the relevant literature on roles [START_REF] Steimann | On the representation of roles in object-oriented and conceptual modelling[END_REF][START_REF] Masolo | Social Roles and their Descriptions[END_REF][START_REF] Loebe | Abstract vs. social roles-Towards a general theoretical account of roles[END_REF][START_REF] Mizoguchi | Families of roles: A new theory of occurrent-dependent roles[END_REF]. Mizoguchi et al. [START_REF] Mizoguchi | Families of roles: A new theory of occurrent-dependent roles[END_REF] maintain that "play a role" has two components which they call "holding a role" and "performing a role". To take their example, if Mary is employed as a teacher, she is still a teacher when she is asleep: she holds a teacher role even when she is asleep and does not perform this role (by e.g. giving classes at school). "Holding a role" and "performing a role" in their terminology would coincide with the bearing and realization of BFO:roles, respectively (see Table 1).

2.3.!A Theory of Dispositions

We will explain dispositions as a preliminary to presenting our dispositional view of affordances. BFO considers a disposition as an "internally grounded realizable entity", that is "a realizable entity that exists because of certain features of the physical make-up of the independent continuant that is its bearer" ([10], p. 101) (see below Section 3.2.1 for how we understand "grounding" here). Classical examples of dispositions include fragility (the disposition of a glass to break when pressed with a certain force) and solubility (the disposition of salt to dissolve when put in a solvent).

We will be more specific about dispositions in two respects. First, following Röhl and Jansen [START_REF] Röhl | Representing dispositions[END_REF], what causes a disposition to be realized (the "trigger") will be restricted to a process, to simplify the representation: e.g. the fragility of a glass is triggered by a process of pressing the glass with a certain force. We thus use the has_trigger relation between a disposition and its triggering process [START_REF] Röhl | Representing dispositions[END_REF]. Second, we utilize Röhl & Jansen's [START_REF] Röhl | Representing dispositions[END_REF] framework for dispositions, in which a disposition is characterized by relatively specific processes (see Barton et al. [19] for a discussion), characterizing e.g. fragility as a disposition that is triggered only by pressuring processes exceeding a given intensity, and realized only by processes of the object breaking.

We will also use a theory of mereology among dispositions [START_REF] Barton | A taxonomy of disposition-parthood[END_REF], which introduces several kinds of disposition-parthood relations. A first one holds, for example, between the general attractive and repulsive character of a magnet on one hand, and its disposition to attract unlike pole (as well as its disposition to repulse like pole) on the other hand. It is called "mod-parthood", as a mod-part characterizes a "mode" in which the dispositionwhole can behave. A second kind of disposition-parthood, named "add-parthood", is the one that holds between, for example, the solubility of a tablet on one hand, and the solubility of its left half (or the solubility of its right half) on the other hand (see [START_REF] Barton | A taxonomy of disposition-parthood[END_REF] for more details, and a formal description of the axioms satisfied by those relations). We will say, in such a case, that the solubility of the tablet is the "add-sum" of the solubility of its left half and the solubility of its right half.

3.!Modeling Roles with Affordances

3.1.!Baldoni et al.'s "Roles as Affordances" and Beyond

According to Boella et al. [START_REF] Boella | Roles, an interdisciplinary perspective[END_REF], Baldoni et al. [START_REF] Baldoni | Modelling the interaction between objects: Roles as affordances[END_REF] propose to consider roles as "sets" (which we will understand here as sums or aggregates) of (Gibsonian) affordances. Their basic idea is that the animal and the environment (in the Gibsonian account of affordances) are respectively the bearer of a role, and something or someone that influences the rolebearer. For example, in a treatment relation between a health professional Mary and a patient John, John is (part of) an "environment" in which Mary can perform treatments. Thus, John's "patient of Mary" role would be identified with an affordance, and Mary's role of John's caregiver would be identified with her agent's effectivity (the counterpart of affordance, as we will explain below) to treat John.

Baldoni et al. [START_REF] Baldoni | Modelling the interaction between objects: Roles as affordances[END_REF] provide thus a first step towards an affordance-based approach to roles. As Boella et al. [START_REF] Boella | Roles, an interdisciplinary perspective[END_REF] say, their idea of connecting roles with affordances is motivated by the widely acknowledged, relational or interactional character of roles [START_REF] Masolo | Social Roles and their Descriptions[END_REF]. As a matter of fact, affordances are inherently interactional: they exist only in virtue of the complementary animal-environment interrelationship. Their initial proposal needs further elaboration, however, in order to become a full-fledged affordance-based ontology of roles. First, affordances cannot be fully understood unless their "reciprocal effectivities" are (and vice versa) [START_REF] Toyoshima | A formal representation of affordances as reciprocal dispositions[END_REF]. An affordance-based view of roles must therefore take into account effectivities and their combinations with affordances as well. For another, roles are intimately related with contexts [START_REF] Masolo | Social Roles and their Descriptions[END_REF][START_REF] Loebe | Abstract vs. social roles-Towards a general theoretical account of roles[END_REF][START_REF] Mizoguchi | Families of roles: A new theory of occurrent-dependent roles[END_REF] (see [START_REF] Baclawski | Ontology summit 2018 communiqué: Contexts in context[END_REF] and [START_REF] Toyoshima | Contexts: A grounding perspective[END_REF] for their general discussion and their ontological analysis, respectively), as is indicated by the optionality of BFO:Role. The contextuality of roles needs to be ontologically connected to affordances and effectivities.

The extent of the analysis needs to be specified though. First, the notion of role can be understood in a very general sense in ontology (see e.g. [START_REF] Loebe | Abstract vs. social roles-Towards a general theoretical account of roles[END_REF]), and not all of them are accountable in terms of affordance and effectivities (consider, e.g. the role of the rose as a bearer of its red color quality). We will thus restrict our investigation to what we will call "causal roles", which we define informally, for now, as roles that characterize some causal relationship -e.g. the causal role of this stairs into John moving upwards (here we leave open the question whether all instances of BFO:Role are causal roles or not).

Second, not all causal roles can be analyzed in terms of affordances and effectivities. For example, the causal role of gear1 to rotate gear2 inside watch0 does not involve any agent (gear1 has arguably no agentivity), and is therefore not analyzable in terms of affordances and effectivities. Therefore, our analysis will be limited to causal roles that involve an agent (typically, an animal, a robot, etc.) and an environment (we will not address here the intricate problem of characterizing formally the notions of agent and environment).

3.2.!Affordances as Reciprocal Dispositions with Respect to Effectivities

As mentioned earlier, affordances are something that the environment "affords" agents such as animals. Classical examines include the climbability of stairs and the capability of gaps to hide. Our ontology of affordances [START_REF] Toyoshima | Modeling Affordances with Dispositions[END_REF][START_REF] Toyoshima | A formal representation of affordances as reciprocal dispositions[END_REF][START_REF] Toyoshima | Linking image schemas with affordances: An ontological approach[END_REF] draws upon Turvey's [START_REF] Turvey | Affordances and prospective control: An outline of the ontology[END_REF] dispositional construal of affordances: "An affordance is a particular kind of disposition, one whose complement is a dispositional property of an organism" (p. 179). He also calls this complement an "effectivity". For instance, the affordance of stairs is their disposition to support an organism as it moves upward or downward on it, and its complement is the disposition (effectivity) of an organism to move upward or downward when using stairs. This dispositional view of affordances is arguably the most straightforward interpretation of Gibson's original notion of affordance (see [START_REF] Heras-Escribano | The philosophy of affordances[END_REF] for a discussion); and it meshes well with Baldoni et al.'s [START_REF] Baldoni | Modelling the interaction between objects: Roles as affordances[END_REF] affordance-based approach to roles that is inspired by Gibsonian affordances.

3.2.1.!Reciprocal Dispositions and their Causally Equivalent Sum

To formalize affordances along with Turvey's line of argument, we elaborated in a former work [START_REF] Toyoshima | A formal representation of affordances as reciprocal dispositions[END_REF] on the idea of reciprocal disposition (see [START_REF] Martin | The mind in nature[END_REF][START_REF] Goldfain | Dispositions and the infectious disease ontology[END_REF]). Classical examples of reciprocal dispositions include a key and a lock such that the former opens the latter: e.g. key1 has the disposition d1 to open lock2, and lock2 has the disposition d2 to be opened by key1 (hence: INH(d1, key1) and INH(d2, lock2)). We introduced [START_REF] Toyoshima | A formal representation of affordances as reciprocal dispositions[END_REF] the relation of being reciprocal dispositions, that we will write here as the binary relation "REC". REC is non-reflexive, symmetric, and is constrained by axioms claiming that 1) two reciprocal dispositions are triggered by exactly the same processes, 2) they are realized in exactly the same processes and 3) their bearers have no common part. d1 and d2 were analyzed as reciprocal dispositions in this sense (that is, we have REC(d1, d2)) : 1) they are triggered by processes of key1 being inserted and turned in lock2, 2) they are realized by processes of key1 opening lock2, and 3) key1 and lock2 have no common parts.

We also introduced [START_REF] Toyoshima | A formal representation of affordances as reciprocal dispositions[END_REF] the notion of "causally equivalent sum" d3 (disposition) of d1 and d2, that we will formalize using the ternary relation CES (here: CES(d1,d2,d3)) Like d1 and d2, d3 is triggered by key1 being inserted and turned in lock2, and realized by processes of key1 opening lock2. However, d3 is borne by the mereological sum of key1 and lock2 (which we will write by "key1+lock2"), whereas d1 is borne by key1 and d2 by lock2. Since d1, d2, and d3 have the same triggers and realizations, they have, intuitively, the same "causal import". We can say intuitively that d1 describes the causal situation from the perspective of key1, d2 describes it from the perspective of lock2, and d3 describes it from the perspective of key1+lock2. Note that two reciprocal dispositions are always add-part of their causally equivalent sum [START_REF] Toyoshima | A formal representation of affordances as reciprocal dispositions[END_REF]. In particular, d1 and d2 are addparts of d3. Since d1 is inherently directed towards lock2, and d2 is inherently directed towards key1, we call reciprocal dispositions such as d1 and d2 "individual-directed".

As seen earlier, the distinction between roles and dispositions in BFO is formulated partly in terms of grounding. This notion could be formalized in various ways, that exceed the scope of this paper (but see [START_REF] Toyoshima | Natural necessity: An introductory guide for ontologists[END_REF], and the section 4.3 for an alternative view). In this paper, we will understand grounding as ontological (existential) dependence (see [START_REF] Hoeltje | Varieties of dependence: Ontological dependence, grounding, supervenience, response-dependence[END_REF] for a discussion of the connections between both). More specifically, dispositions will be considered here as ontologically dependent on their bearers, but not any external entity; and roles as ontologically dependent not only on their bearers, but also on some external entity.

What we called "reciprocal dispositions" in [START_REF] Toyoshima | A formal representation of affordances as reciprocal dispositions[END_REF] depend existentially on the physical make-up of some entities that are external to them. For instance, d1 (of key1) and d2 (of lock2) depend existentially on the physical make-ups of both key1 and lock2. Consequently, d1 and d2 can be subject to so-called "Cambridge change" [START_REF] Geach | God and the Soul[END_REF]: if key1 disappears, then so does d2, even if d2's bearer, namely lock2, did not change. Similarly, if lock2 disappears, then so does d1, even if d1's bearer, namely key1, did not change. Thus, d1 and d2 cannot be classified as dispositions if we follow strictly BFO's current characterization of dispositions as being "internally grounded". Therefore, we will call them here more cautiously "reciprocal realizable entities" (abbreviated "reciprocal REs") -see section 4.3 for a discussion of what kind of realizable entities those could be. Two reciprocal REs can intuitively be seen as two aspects of a more encompassing disposition, when viewed from the perspective of a part of the bearer of this disposition; for example, d1 would be an aspect of d3, when viewed from the perspective of key1; and d2 would be an aspect of d3, when viewed from the perspective of lock2.

Reciprocal REs are very similar to dispositions as they are "potentialities" that can be triggered and realized by processes; and they differ from dispositions by not being internally grounded. Therefore, the mereological theory of dispositions mentioned above (add-parthood, mod-parthood, etc.) can be directly adapted to reciprocal REs.

3.2.2.!Individual-directed Affordances and Affectivities and Affordance/Effectivity Complex

Any individual-directed effectivity (resp. affordance) has some individual-directed affordance (resp. effectivity) as a reciprocal RE. For instance, the affordance a0 of stairs0 enabling John to move up and John's effectivity e0 to move up using stairs0 are reciprocal REs: they both can be triggered by (something like) the process of John contracting some leg muscles on stairs0 and be realized in the process of John climbing up stairs0. Formally, we endorse the two following axioms (using the taxonomy described in Fig. 1 Finally, according to Turvey [START_REF] Turvey | Affordances and prospective control: An outline of the ontology[END_REF], affordances depend existentially not only on effectivities but also on what we called "affordance/effectivity complex" [START_REF] Toyoshima | A formal representation of affordances as reciprocal dispositions[END_REF]. To illustrate this: the affordance a0 and the effectivity e0 both exist if and only if there exists the corresponding affordance/effectivity complex: a dispositional property c0 that is borne by John+stairs0. In our analysis [START_REF] Toyoshima | A formal representation of affordances as reciprocal dispositions[END_REF], c0 is the "causally equivalent sum" of a0 and e0 (it is to a0 and e0 what d3 above was to d1 and d2). Note that a0 and e0 inherit their causal import from the disposition c0: a0 can be seen as the perspective from the point of view of stairs0 on c0, and e0 as the perspective from the point of view of John on c0.

More generally, any affordance and its reciprocal effectivity can be associated to an affordance-effectivity complex (AFF-EFF), a disposition that is their causally equivalent sum: AFF(a) " EFF(e) " REC(a,e) → !c, [CES(a,e,c) " AFF-EFF(c)]

3.3.!Roles and Individual-directed Affordances/Effectivities

3.3.1.!Counter-role and Contextuality

Since an affordance-based perspective on roles highlights their relational feature, let us focus upon the intuition (mentioned by Boella [START_REF] Boella | Roles, an interdisciplinary perspective[END_REF]) that every role should have at least one related "counter-role". In our John/stairs0 example, John's effectivity e0 is a "potential climber-of-stairs0 RE" whose (potential) realizations comprise processes of John climbing stairs0. Note the use of the term "potential": indeed, John has this effectivity even when he is not climbing stairs0, including the extreme scenario in which he will never climb stairs0. Symmetrically, stairs0 bears the affordance a0, which is a "potential climbee-by-John RE" (here again, this RE inheres in stairs0 even when it is not climbed by John). The fact that a0 and e0 are reciprocal REs will be the basis for formalizing the aforementioned intuition of role and counter-role.

Our affordance-based account of roles may also allow us to analyze the contextuality of roles more carefully than Baldoni et al. According to Baclawski et al. [START_REF] Baclawski | Ontology summit 2018 communiqué: Contexts in context[END_REF], a context is something in terms of which something (else) can be determined. In our John/stairs0 scenario, a0 and e0 are reciprocal REs; but to understand their causality, one needs to consider their affordance/effectivity complex c0 because it is the primary source of their causality. c0 is triggered (like a0 and e0) by John contracting some leg muscles and realized (like a0 and e0 too) by John moving up stairs0; but contrarily to a0 and e0, it is a bona fide disposition, and inheres in the sum John+stairs0. In this sense, c0 provides the contextuality of a0 and e0, because their causal import is determined by the causal import of c0.

3.3.2.!Role as a Realized Affordance or as a Realized Effectivity

To be sure, the terms "potential climber" and "potential climbee" are not commonly used. We are usually more interested in someone being an actual "climber", or something being actually climbed -that is, being an actual "climbee". Therefore, the terms "climber role" and "climbee role" typically describe roles that are being performed (remember the distinction we introduced in 2.2). We can formalize John's "climber-of-stairs0 role" as being a0, but only when it is realized in John climbing stairs0. Similarly, we can formalize stairs0's "climbee-by-John role" as being e0, but only when it is realized in a process of John climbing stairs0. That is, when a process of John climbing stairs0 obtains, e0 become an instance of climber-role, and a0 becomes an instance of climbeerole. More generally, and said differently: a climber role is a "potential climber" effectivity that is being realized, and a climbee role is a "potential climbee" affordance that is being realized. Introducing the first-order, temporalized predicates of climber role (CLIMBER), climbee role (CLIMBEE), potential climber effectivity (P-CLIMBER), potential climbee affordance (P-CLIMBEE), and realized in (REAL), we could formalize this by the following definitions: CLIMBER(r,t)=def P-CLIMBER(r,t) p REAL(r,p,t) CLIMBEE(r,t)=def P-CLIMBEE(r,t) p REAL(r,p,t)

3.3.3.!Role as a Sum of Affordances or Effectivities

We have seen a case in which a role can be identified with either an affordance or an effectivity. As Baldoni et al. [START_REF] Baldoni | Modelling the interaction between objects: Roles as affordances[END_REF] observe, however, one needs to consider roles with respect to multiple affordances (and effectivities) in order to articulate complex behaviors of objects (such as agents) in the real world. Suppose that Pat addresses Sam: Pat bears an addresser role relatively to Sam and Sam bears an addressee (counter-)role relatively to Pat. Suppose also for simplicity that to address a person consists in 1) looking at and 2) speaking to the person.

In this scenario, we can recognize two affordances inhering in Sam (see Fig. Let us consider some relevant basic roles here, namely Pat's speaker-to-Sam role and Sam's speakee-by-Pat role (that is, the role of being spoken to by Pat; note that this is not identical to a role of Pat-listener, as Pat may speak to Sam while Sam is not listening to her). Informally, and similarly to the terms "climber role" and "climbee role", the term "speaker role" and "speakee role" typically need to be performed to exist. Indeed, one would not say that Pat plays a role of speaker-to-Sam by her merely having the possibility to speak to him: we typically say that she has this role when she actively speaks to him. Therefore, the use of the term "speaker" differs from the use of, say, the term "nurse". Indeed, we state that a person has a "nurse" role even if she is not actively performing nursing action (see below section 4.2 for more discussion on social roles); however, we say that a person has a "speaker" role only if she is actively speaking (except in some cases, when the term "speaker" denotes e.g. an invited speaker to a conference, which is a role that the person keeps some time before and after the event).

Therefore, Pat's speaker-to-Sam role cannot be always identified with espeak, nor Sam's speakee-by-Pat role always with aspeak. Indeed, those affordance and effectivity exist even when Pat does not speak to Sam. The fact that Pat bears the effectivity espeak does not mean that she is actively speaking to Sam, but that she has the potential, in the right set of circumstances, to speak to Sam. Therefore, espeak is a Pat's "potential speakerto-Sam" effectivity: should Pat decide to speak to Sam, she could do so. Similarly aspeak is a "potential speakee-by-Pat" affordance. As we did for the climber and climbee roles, we can formalize Pat's (actual) speaker-to-Sam role as being identical to espeak, but only when it is realized in a process of Pat speaking to Sam. Similarly, we can formalize Sam's (actual) speakee-by-Pat role as being identical to aspeak, but only when it is realized in a process of Pat speaking to Sam. More generally: a speaker role is a potential speaker effectivity that is realized, and a speakee role is a potential speakee affordance that is realized. Introducing the first-order, temporalized predicates of speaker role (SPEAKER), speakee role (SPEAKEE), potential speaker effectivity (P-SPEAKER), potential speakee affordance (P-SPEAKEE), and realized in (REAL), we could formalize this by the following definitions: SPEAKER(r,t)=def P-SPEAKER(r,t) p REAL(r,p,t) SPEAKEE(r,t)=def P-SPEAKEE(r,t) p REAL(r,p,t) We can now turn to analyzing Sam's addressee role and Pat's addresser role using the above-mentioned mereological theory between dispositions (which we adapt straightforwardly to a mereological theory between reciprocal REs, as explained earlier). Let's start with the former. The add-sum of alook and aspeak, which we call "alook+speak", is the affordance inhering in Sam that can be realized by Pat looking at Sam and speaking to Sam: by being in Pat's environment, Sam affords her to look at him and speak to him -that is, affords her to address him. Since this RE exists even if Pat is not actively looking at and speaking to Sam, it cannot be always identified with Sam's addressee-by-Pat role; it is rather Sam's potential addressee-by-Pat affordance. However, similarly to what we just described, Sam's addressee-by-Pat role can be identified with alook+speak when it is realized, that is, when Pat does indeed look at and speak to Sam. And Pat's addresserto-Sam role also can be identified with the effectivity elook+speak when it is realized.

It is also well worth noting that some roles are explicable in terms of both affordances and effectivities. Consider e.g. Sam's "Pat-interlocutor role" that is manifested when Pat addresses him and he addresses Pat in turn: it can be minimally characterized with his addressee-by-Pat role (whose counter-role is Pat's addresser-to-Sam role) and his addresser-to-Pat role (whose counter-role is Pat's addressee-by-Sam role), which can be in turn analyzed using affordances and effectivities, respectively. A straightforward suggestion would be to represent this interlocutor role as a sum of her the affordances and effectivities underlying his addressee role and his addresser role, when this sum is realized (note that this could not be an add-sum, as one is usually not both addressing a person and addressed by this person at the same time). This line of work will be left for the future.

Finally, note that some roles would better be analyzed as having some affordances and effectivities as mod-parts, rather than add-parts. For example, the role of a health professional could be (in a first approximation) considered as having as mod-part their effectivity to diagnose a patient and as another mod-part their effectivity to treat them. Indeed, a health professional will typically diagnose a patient, or treat a patient, but generally not both at the same time. Hence, this role can be realized by one or the other effectivity being realized. Future work should analyze in more details the various kinds of parthood that can be involved in such causal roles.

3.4.!A Brief Summary

Let us summarize the connections between the entities introduced above. The contextuality of reciprocal causal REs can be analyzed in terms of their causally sum equivalent, which is a disposition; for example, the reciprocal REs d1 of key1 to open lock2, as well as d2 of lock2 to be opened by key1, get their causality from the more fundamental disposition d3 borne by key1+lock2. In particular, individual-directed affordances and effectivities are reciprocal REs that can be analyzed in terms of their affordance/effectivity complex (a disposition), from which they get their contextuality; e.g. the effectivity of John to climb up stairs0 and the affordance of stairs0 to be climbed by John are merely aspects of the more fundamental disposition c0, an affordance/effectivity complex that depends existentially on the physical make-up of its bearer John+stairs0. Subsequently, we have introduced more elaborate REs, such as Sam's potential addressee-by-Pat affordance (alook+speak) and Pat's potential addresserto-Sam effectivity (elook+speak), which can be analyzed as add-sums of more basic affordances or effectivities (and some other relevant REs might be identified instead with mod-sums of such affordances or effectivities). Finally, and most importantly, we have explained how Sam's addressee-by-Pat role and Pat's addresser-to-Sam role can be identified with those affordances and effectivities when they are realized.

4.!Discussion

4.1.!Family-directed Affordances and Effectivities

In the aforementioned key-lock example, d1 and d2 are "individual-directed": they depend (existentially) on individual entities lock2 and key1. However, we can introduce dispositions d f 1 and d f 2 that are entwined with, but differ from d1 and d2, and not subject to Cambridge change [START_REF] Toyoshima | A formal representation of affordances as reciprocal dispositions[END_REF][START_REF] Toyoshima | Linking image schemas with affordances: An ontological approach[END_REF]. Let Lock2 and Key1 be classes whose instances are locks (qualitatively) similar to lock2 and keys (qualitatively) similar to key1, respectively. Then let us define d f 1 and d f 2 as follows:

•! d f 1 as the disposition of key1 to open instances of Lock2.

•! d f 2 as the disposition of lock2 to be opened by instances of Key1.

Contrary to d1 and d2, d f 1 and d f 2 are "family-directed": they depend on the families Lock2 and Key1, respectively.

We can then accordingly introduce the notion of individual-directed and familydirected affordances and effectivities [START_REF] Toyoshima | A formal representation of affordances as reciprocal dispositions[END_REF]. Recall the John-stairs example in which we can introduce the affordance a0 of stairs0 for John to move up, and John's effectivity e0 to move up using stairs0. Here a0 and e0 are individual-directed because they depend existentially on John and stairs0, respectively. By introducing the general classes Person and Stairs (whose instances include John and stairs0, respectively), we can introduce a family-directed affordance a f 0 that is closely related with a0, namely the affordance of stairs0 to enable instances of Person to move up. Similarly, we can introduce a familydirected effectivity e f 0, closely related with e0, of John to move up using instances of Stairs. As we will now discuss, such family-directed affordances and effectivities could then be used as a basis to represent social roles.

4.2.!Loebe's Three Kinds of Roles

Loebe [START_REF] Loebe | Abstract vs. social roles-Towards a general theoretical account of roles[END_REF] proposes three kinds of roles (that are not necessarily mutually exclusive): relational, processual, and social. (His proposal is based on the upper ontology General Formal Ontology [START_REF] Herre | General Formal Ontology (GFO): A foundational ontology for conceptual modelling[END_REF], but its general utility is recognized by Guarino [START_REF] Guarino | So Far, So Close[END_REF]) That is:

•! Relational roles correspond to the way in which the role-bearers are related with respect to their "actual relationship" [START_REF] Guarino | So Far, So Close[END_REF]. •! Processual roles correspond to the role-bearer's ways of participation in processes: e.g. the mover role (i.e. a process) when John moves a pen. •! Social roles correspond to the way in which the role-bearer behaves in the social world. To take Masolo et al.'s [START_REF] Masolo | Social Roles and their Descriptions[END_REF] examples: professors and presidents.

Our theory can account (at least partially) for the former two kinds of roles. First, causal roles such as looker and lookee roles are arguably relational roles (although not all relational roles involve a causal component, cf. the example above of the rose having a role of bearer of its red-quality). In addition, at least some processual roles are (parts of) realizations of reciprocal REs: e.g. John's pen0-mover processual role is (part of) the realization of John's "potential pen0-mover effectivity" (whose reciprocal RE is the "potential movee-by-John affordance" of pen0). However, social roles are more intricate, as Loebe explains. Some roles that have a social component, such as "addresser" or "addressee", have been analyzed above. But a full analysis of social roles is out of scope of the present paper. As a matter of fact, generally, we can identify three central features of social roles. First, a behavioral dimension: a social role-bearer behaves in a given way; e.g., a nurse provides care for his patient. This dimension can be captured in many cases by the family-directed affordances and effectivities that have been presented above. For example, a nurse has a family-directed effectivity to provide care to patients in general, or to patients of a given kind -and not only an individual-directed effectivity to provide care to a particular patient. Some of them might however be captured by individual-directed affordances and effectivities: consider e.g. professions that only serve a specific queen or emperor. Second, some social roles have a directive dimension. Indeed, some social role-bearers behave in a way that is described by some guidelines, e.g. a nurse following a nurse guidebook about how to treat his patients (see [START_REF] Masolo | Social Roles and their Descriptions[END_REF] for a few pointers on this dimension). Third, some social roles have a normative dimension (see [START_REF] Ethier | An ontological analysis of drug prescriptions[END_REF] for more considerations on the difference between the directive and normative dimensions). Indeed, some social role-bearers have some obligation to behave in the above-mentioned way, and/or other related agents have some associated rights. For example, a nurse has an obligation to provide care to his patients, and a patient has a right to receive care from nurses at a health institution. Therefore, a closer analysis of social roles, especially their normative dimensions, will require an established theory of social ontology [START_REF] Searle | The construction of social reality[END_REF][START_REF] Searle | Making the Social World: The Structure of Human Civilization[END_REF].

4.3.!What is the Nature of Reciprocal REs?

We have so far left open the nature of reciprocal REs. There are at least three ways to classify them more precisely in BFO. A first possibility would be to classify them, as in our former work [START_REF] Toyoshima | A formal representation of affordances as reciprocal dispositions[END_REF], as dispositions. This would require to modify BFO's definition of disposition to include relational dispositions that can be partly externally groundedsimilarly to BFO's relational qualities or UFO's relators [START_REF] Guizzardi | Ontological considerations about the representation of events and endurants in business models[END_REF][START_REF] Guarino | Relationships and events: towards a general theory of reification and truthmaking[END_REF][START_REF] Guizzardi | The problem of transitivity of part-whole relations in conceptual modeling revisited[END_REF]. A second possibility would be to argue from their external groundedness that they should be classified under BFO:Role. However, as mentioned earlier, roles are also characterized in BFO by their optionality: a role "exists because the bearer is in some special physical, social, or institutional set of circumstances in which the bearer does not have to be". For example, the RE d1 of key1 to open lock2 exists because key1 is in a world where lock2 exists. However, it remains debatable whether this can be counted as a "physical circumstance in which the bearer does not have to be"; if not, then such reciprocal REs could not be classified under BFO:Role. Finally, a last possibility would be to introduce a new class of realizable entities in BFO that would include reciprocal REs. We will leave the considerations of those three options for future work.

5.!Conclusion

We developed an affordance-based account of some causal roles based on the BFO understanding of roles (as optional and externally grounded realizable entities), Baldoni et al.'s [START_REF] Baldoni | Modelling the interaction between objects: Roles as affordances[END_REF] insights into "roles as affordances", and our previous dispositional ontology of affordances [START_REF] Toyoshima | Modeling Affordances with Dispositions[END_REF][START_REF] Toyoshima | A formal representation of affordances as reciprocal dispositions[END_REF][START_REF] Toyoshima | Linking image schemas with affordances: An ontological approach[END_REF]. More specifically, we developed an analysis of some causal roles in terms of individual-directed affordances/effectivities (or sums of those). The overall contention here is that some roles, namely causal roles that involve an agent and an environment, can be identified with sum of such affordances and/or effectivities when they are realized, because they are deeply connected to the agent-environment interrelationship. Note that this could easily be generalized in analyzing causal roles that do not involve an agent and an environment (such as the role of gear1 in rotating gear2) as (sum of) reciprocal REs when they are realized (such as the RE of gear1 to potentially rotate gear2 when it is realized). We also briefly discussed our theory of causal roles in regard to Loebe's [START_REF] Loebe | Abstract vs. social roles-Towards a general theoretical account of roles[END_REF] three kinds of roles. Our analysis aimed at being compatible with the BFO framework, and we strive to adapt it to other upper ontologies.

This work leaves open several questions, such as an investigation of the articulation between the processes that an affordance enables (e.g. moving up) and the states that this affordance enables to reach (e.g. reaching the second floor). Another theoretical question would be how to relate this model with Martin's model of dispositions that are activated in the presence of mutual activation partners [START_REF] Martin | The mind in nature[END_REF]. In the future we will further our affordance-based account of roles to the social domain, thereby contributing to the development of a mid-level ontology for the social domain [START_REF] Jansen | Towards an upper-level ontology for the social domain[END_REF]. This requires e.g. spelling out formally the relationship between individual-directed and family-directed affordances/effectivities, and also considering the cases where the bearer of a (counter-)role is the collective [START_REF] Wood | Considering Collectives: Roles, Members and Goals[END_REF] (i.e. the group of individuals). The latter task may warrant exploration of group agency [START_REF] Porello | The Ontology of Group Agency[END_REF] and organizational identity [START_REF] Ferrario | Organisations and Variable Embodiments[END_REF].

Figure 1 .

 1 Figure 1. Taxonomy of relevant classes and their associate first-order predicates

2 ): 1 )

 21 alook, his affordance to be looked by Pat and 2) aspeak, his affordance to be spoken to by Pat (note that we are not speaking of him authorizing Pat to talk to him, but him affording Pat to talk to him by constituting part of Pat's environment). We can also identify two counterpart effectivities in Pat: 1) elook, her effectivity to look at Sam and 2) espeak, her effectivity to speak to him. alook is a reciprocal RE of elook: REC(alook, elook) In particular alook and elook (i) are both triggered by the same process of Sam being into Pat's field of vision and Pat directing her attention at Sam and (ii) are both realized in the same process of Pat looking at Sam. Similarly, aspeak is a reciprocal RE of espeak: REC(aspeak, espeak) They are both triggered by Sam being into Pat's voice range and Pat closing her vocal cords and exhaling, and both realized by Pat speaking to Sam. Note also that all those affordances and effectivities are individual-directed, in the sense that they depend on the individuals Pat and Sam (see section 4.1 for the contrast with family-directed affordances and effectivities).

Figure 2 .

 2 Figure 2. Examples of affordances and effectivities that can become roles when realized

Table 1 .

 1 "play a role" in[START_REF] Mizoguchi | Families of roles: A new theory of occurrent-dependent roles[END_REF] [START_REF] Mizoguchi | Families of roles: A new theory of occurrent-dependent roles[END_REF] and in BFO[START_REF] Arp | Building Ontologies with Basic Formal Ontology[END_REF] with an illustrative example

	Mizoguchi et al. (2015)	BFO	Example: Mary's teacher role
	hold a role	bear a role	Mary being hired as a teacher.
	perform a role	a role is realized	Mary giving classes at school.

Acknowledgments

We would like to thank two anonymous reviewers for their feedback. AB would also like to thank Barry Smith and audience from a talk at the department of biomedical informatics grand rounds at University at Buffalo in December 2018 for feedback on earlier work on which the present work is based. FT acknowledges financial support by the SPOR Canadian Data Platform (CIHR).


The functionalization of three-dimensional (3D) covalent organic frameworks (COFs) is essential to broaden their applications. However, the introduction of organic groups with electroactive abilities into 3D COFs are still very limited. Herein we report the first case of 3D tetrathiafulvalene-based COFs (3D-TTF-COFs) with non-or 2-fold interpenetrated pts topology and tunable electrochemical activity. The obtained COFs show high crystallinity, permanent porosity, and large specific surface area (up to 3000 m 2 /g). Furthermore, these TTF-based COFs are redox active to form organic salts that exhibit tunable electric conductivity (as high as 1.4  10 -2 S cm -1 ) by iodine doping . These results open a way towards designing 3D electroactive COF materials and promote their applications in molecular electronics and energy storage.

Covalent organic frameworks (COFs), as an exciting new type of crystalline porous polymers, are made from light elements, typically H, B, C, N and O, which crystallize into periodic networks by the formation of reversible covalent bonds. [START_REF] Côté | Crystalline, Covalent Organic Frameworks[END_REF][START_REF] Ding | Covalent Organic Frameworks (COFs): from Design to Applications[END_REF][START_REF] Huang | Covalent Organic Frameworks: a Materials Platform for Structural and Functional Designs[END_REF][START_REF] Diercks | The Atom, the Molecule, and the Covalent Organic Framework[END_REF] Owing to their high porosity, large specific surface area and good thermal/chemical stability, the COF materials have attracted much attention for considerable potential in gas storage and separation, 5- 7 catalysis, [START_REF] Ding | Construction of Covalent Organic Framework for Catalysis: Pd/COF-LZU1 in Suzuki-Miyaura Coupling Reaction[END_REF][START_REF] Vyas | A Tunable Azine Covalent Organic Framework Platform for Visible Light-Induced Hydrogen Generation[END_REF][START_REF] Peng | Synthesis of a Sulfonated Two-Dimensional Covalent Organic Framework as an Efficient Solid Acid Catalyst for Biobased Chemical Conversion[END_REF][START_REF] Wang | Homochiral 2D Porous Covalent Organic Frameworks for Heterogeneous Asymmetric Catalysis[END_REF][START_REF] Sun | Flexibility Matters: Cooperative Active Sites in Covalent Organic Framework and Threaded Ionic Polymer[END_REF] organic electronics, [START_REF] Wan | A Belt-Shaped, Blue Luminescent, and Semiconducting Covalent Organic Framework[END_REF][START_REF] Bertrand | Thiophene-Based Covalent Organic Frameworks[END_REF][START_REF] Dogru | A Photoconductive Thienothiophene-Based Covalent Organic Framework Showing Charge Transfer Towards Included Fullerene[END_REF][START_REF] Du | Ionic Covalent Organic Frameworks with Spiroborate Linkage[END_REF] and many others. [START_REF] Oh | A Cryogenically Flexible Covalent Organic Framework for Efficient Hydrogen Isotope Separation by Quantum Sieving[END_REF][START_REF] Chandra | Phosphoric Acid Loaded Azo (-N═N-) Based Covalent Organic Framework for Proton Conduction[END_REF][START_REF] Zhou | One-Step Construction of Two Different Kinds of Pores in a 2D Covalent Organic Framework[END_REF][START_REF] Cai | Tunable Electrical Conductivity in Oriented Thin Films of Tetrathiafulvalene-Based Covalent Organic Framework[END_REF][START_REF] Jin | Two-Dimensional sp2 Carbon-Conjugated Covalent Organic Frameworks[END_REF][START_REF] Guo | Fast Ion Transport Pathway Provided by Polyethylene Glycol Confined in Covalent Organic Frameworks[END_REF][START_REF] Guan | Chemically Stable Polyarylether-Based Covalent Organic Frameworks[END_REF] Over the past decade, most of the reported work on COFs, however, were focused on two-dimensional (2D) COFs with layered eclipsed structures. Three-dimensional (3D) COFs, especially 3D functionalized COFs, have recently attracted extensive interest due to their unique porous features and excellent performances. 24- 29 We have synthesized a series of 3D functionalized COFs by the pre-synthesis or post-modification approach, including 3D Salphen-based COFs as catalytic antioxidants, [START_REF] Yan | Three-dimensional Salphen-based Covalent-Organic Frameworks as Catalytic Antioxidants[END_REF] 3D ionic liquidcontaining COFs for gas separation, 31 3D carboxy-functionalized COFs with selective extraction of lanthanide ions, [START_REF] Lu | Postsynthetic Functionalization of Three-Dimensional Covalent Organic Frameworks for Selective Extraction of Lanthanide Ions[END_REF] and so on. [START_REF] Fang | 3D Microporous Base-Functionalized Covalent Organic Frameworks for Size-Selective Catalysis[END_REF][START_REF] Fang | 3D Porous Crystalline Polyimide Covalent Organic Frameworks for Drug Delivery[END_REF][START_REF] Li | Three-Dimensional Covalent Organic Frameworks with Dual Linkages for Bifunctional Cascade Catalysis[END_REF][START_REF] Li | Three-Dimensional Ionic Covalent Organic Frameworks for Rapid, Reversible, and Selective Ion Exchange[END_REF] It must be noted, however, that the functionalization of 3D COFs remains largely unexplored, such as 3D electroactive COFs in particular. Thus, the development of new 3D functionalized COF materials is of critical importance for enriching the structural diversity and expanding their applications. Taking these considerations in mind, we report herein the first case of 3D electroactive COFs containing tetrathiafulvalene (TTF) functional units, denoted as 3D-TTF-COFs. Our results demonstrate that the obtained COFs have rare non-or 2-fold interpenetrated pts topology, high crystallinity and large surface area (˃ 3000 m 2 /g). More importantly, the TTF-based frameworks can be doped with electron acceptors (iodine, I 2 ), and their conducting properties can be tuned from 1.8  10 -7 to 1.4  10 -2 S m -1 by the amount of I 2 and the temperature employed. To the best of our knowledge, this study is the first example of 3D COFs with noninterpenetrated pts topology and the application of 3D COFs as charge-transfer materials. Our strategy for preparation of 3D electroactive COFs is based on a TTF derivative, tetrathiafulvalene-tetrabenzaldehyde (TTF-TBA, Scheme 1a). As we all know, due to their excellent electrical activities, TTF or TTF-based derivatives have played an important role in the development of organic conducting materials. 37- 39 Therefore, by the incorporation of TTF units into 3D porous COFs, the resulting materials will not only promote electronic interactions between TTF molecules but also enable doping with electron acceptors (e.g., I 2 ) to increase their conductivity. As shown in Scheme 1, TTF-TBA (Scheme 1a) was designed as a planar 4-connected building unit, and 1,3,5,7tetraaminoadamantane (TAA, Scheme 1b) or tetra(4aminophenyl)methane (TAPM, Scheme 1c) was chosen as a typical tetrahedral building unit. The condensation of TTF-TBA and TAA or TAPM produced 3D-TTF-COFs, termed as JUC-518 (JUC = Jilin University China, Scheme 1d) and JUC-519 (Scheme 1e). In light of the linking of tetrahedral and planar 4-connected building units, the structures of both COFs are expected to be the pts net (Scheme 1f and 1g). Since the TTF-TBA is connected by TAA as a short tetrahedral building unit (~ 3.1 Å) and TAPM as a long tetrahedral building unit (~ 5.9 Å, Figure S1), the resulting structures tend to be non-and 2-fold interpenetrated pts networks, respectively. 40 The synthesis of 3D-TTF-COFs was carried out by suspending TTF-TBA and TAA or TAPM in the mixed solvent of odicholobenzene (o-DCB) and n-butanol (n-BuOH) in the presence of acetic acid followed by heating at 120 °C for 3 days. A variety of methods were employed for structural characterizations of 3D-TTF-COFs. The morphology was examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM, Figures S2 andS3), which showed isometric crystals with a size of 0.2 m. The Fourier transform infrared (FT-IR) spectrum exhibited a new peak at 1637 cm -1 for JUC-518 or 1625 cm -1 for JUC-519, which is a typical characteristic of C=N bond. The concomitant disappearance of the C=O stretching vibration (1701 cm -1 for TTF-TBA) and the N-H stretching vibration (~3324 cm -1 for TAA and ~3348 cm -1 for TAPM), confirmed the complete transformation of aldehyde and amine groups (Figures S4 andS5). The solid-state [START_REF] Wan | A Belt-Shaped, Blue Luminescent, and Semiconducting Covalent Organic Framework[END_REF] C cross-polarization magic-angle-spinning (CP/MAS) NMR spectroscopy confirmed the presence of carbons from the imine groups by the peak at 154 ppm for JUC-518 or 158 ppm for JUC-519 (Figures S6 andS7). Both 3D-TTF-COFs had high thermal stability (~400 °C) as shown by the thermogravimetric analysis (TGA, Figures S8 andS9), and can be preserved in different organic solvents and aqueous solutions of 1 M HCl or 1 M NaOH (Figures S10 andS11).

The crystal structures of 3D-TTF-COFs were analyzed by the powder X-ray diffraction (PXRD) measurements in conjunction with structural simulations (Figure 1). After 102), ( 200), ( 004), ( 204) and (303) Bragg peaks of the space group P4 2 /m (No. 84). The refinement results can match well with the observed ones with good agreement factors (Rp = 1.87% and ωRp = 2.60% for JUC-518; Rp = 2.68% and ωRp = 4.44% for JUC-519). In addition, we tried alternative structures, such as 2-fold interpenetrated pts net for JUC-518 and non-interpenetrated pts net for JUC-519; however, their simulated PXRDs did match to the experimental ones (Figures S12-15). In consideration of these results, the obtained COFs were proposed to have the expected frameworks with nonor 2-fold interpenetrated pts topology, which show microporous cavities with ~ 1.62 nm for JUC-518 and ~ 0.81 nm for JUC-519 (Figure 2). Remarkably, all the previous COFs with pts topology show interpenetrated structures and small dominated pores (~ 0.60 nm), [START_REF] Lin | A Pyrene-Based, Fluorescent Three-Dimensional Covalent Organic Framework[END_REF][START_REF] Lin | 3D Porphyrin-Based Covalent Organic Frameworks[END_REF][START_REF] Ding | An AIEgen-Based 3D Covalent Organic Framework for White Light-Emitting Diodes[END_REF] and thus the successful preparation of JUC-518 with non-interpenetrated nets will benefit the development of 3D COFs with large pores. The porosity and specific surface areas of 3D-TTF-COFs were determined by N 2 adsorption analysis at 77 K (Figure 3). Both materials show a sharp uptake at a low pressure of P/P 0 < 0.05, which is a typical characteristic of the microporous material. The inclination of isotherms in the 0.9-1.0 P/P 0 range and slight desorption hysteresis can be attributed to the presence of textural mesopores, which is from the agglomeration of COF crystals. [START_REF] Fang | 3D Porous Crystalline Polyimide Covalent Organic Frameworks for Drug Delivery[END_REF] The Brunauer-Emmett-Teller (BET) equation was carried out in the 0.05 < P/P 0 < 0.30 range of their isotherms, indicating BET surface areas of 3018 m 2 g -1 for JUC-518 and 1513 m 2 g -1 for JUC-519 (Figures S18 andS19). Obviously, owing to the non-interpenetrated structure of JUC-518, its BET surface area is much higher than those from all reported 3D COFs with the pts topology (< 1400 m 2 g -1 ). [START_REF] Lin | A Pyrene-Based, Fluorescent Three-Dimensional Covalent Organic Framework[END_REF][START_REF] Lin | 3D Porphyrin-Based Covalent Organic Frameworks[END_REF][START_REF] Ding | An AIEgen-Based 3D Covalent Organic Framework for White Light-Emitting Diodes[END_REF] Pore size distributions of 3D-TTF-COFs calculated based on the nonlocal density functional theory (NLDFT) demonstrated pores with the size of 1.54 nm for JUC-518 and 0.84 nm for JUC-519 (Figure 3, inset), which are in good agreement with those of the proposed model (1.62 nm for JUC-518 and 0.81 nm for JUC-519). Inspired by the abundant presence of TTF functional units, we firstly investigated the electrochemical behavior of 3D-TTF-COFs by cyclic voltammetry (CV). As shown in Figures S20 andS21, both COFs showed a reversible CV profile with two clear redox processes at 0.78 and 1.16 V for JUC-518 and 0.75 and 1.13 V for JUC-519 respectively, revealing that TTF units in COF frameworks retain their redox activities. Furthermore, the electrondonating nature of TTF units and permanent porosity of 3D-TTF-COFs could endow us to develop TTF-based charge-transfer (CT) materials. Both COFs were doped (oxidized) by exposure to I 2 vapor. Figure 4a and4b showed electron paramagnetic resonance (EPR) spectra of JUC-518 and JUC-519 before and after I 2 doping. Obviously, the pristine samples had very weak EPR spectra; however, the doped samples exhibited a significant paramagnetic intensity increased by approximately two orders of magnitude. After I 2 doping, the sharp peaks were observed at g = 2.0068 for JUC-518 and 2.0080 for JUC-519, clearly confirming the enhancing concentration of TTF radical cations. [START_REF] Farges | Organic Conductors: Fundamentals and Applications[END_REF][START_REF] Jérome | Organic Conductors: From Charge Density Wave TTF-TCNQ to Superconducting (TMTSF)2PF6[END_REF][START_REF] Yamada | TTF Chemistry: Fundamentals and Applications of Tetrathiafulvalene[END_REF] The PXRD patterns showed that 3D-TTF-COFs after I 2 doping remained highly crystalline and structurally intact (Figures S16 andS17).

We further investigated the electrical conductivities of I 2 doped 3D-TTF-COFs. Typically, the doped samples were compressed into cylindrical pellets with a diameter of 0.5 cm and a thickness of 0.2 cm. The conductivities were conducted by using gold paste contacts in a two-probe configuration. As shown in Figures 4c-f and S22-37, the temperature dependences of the conductivities in the range 25 to 120 ºC revealed the semiconductor-like behavior of 3D-TTF-COFs after doping with I 2 . Furthermore, the conducting properties of 3D-TTF-COFs could be tuned with doping time from 6 to 48 hrs. These results are summarized in Tables S1 andS2. For example, conductivity of 2.9  10 -7 S cm -1 for JUC-518 at 25 °C is obtained after doping for 6 hrs, which could be increased to 2.7  10 -4 S cm -1 at 25 °C upon extending the doping time to 48 hrs. Subsequently, the conductivity of JUC-518 could be extremely enhanced to 1.4  10 -2 S cm -1 by raising the temperature up to 120 ºC. Notably, the electrical conductivities of 3D-TTF-COFs is higher than those from 2D TTF-based COF powders (~ 10 -5 S cm - 1 ). [START_REF] Ding | A Tetrathiafulvalene-Based Electroactive Covalent Organic Framework[END_REF][START_REF] Jin | Two-Dimensional Tetrathiafulvalene Covalent Organic Frameworks: Towards Latticed Conductive Organic Salts[END_REF] The high conductivities can be attributed to interconnected channels and high surface areas in 3D-TTF-COFs, in which TTF units can be fully oxidized into TTF radical cations.

In summary, we report 3D electroactive TTF-based COFs with non-or 2-fold interpenetrated pts topology, high crystallinity and large permanent porosity. Furthermore, these 3D-TTF-COFs are redox active to form organic salts that exhibit outstanding electric conductivity by doping I 2 . This study not only develops a way towards designing 3D electroactive COF materials, but also promotes their applications in molecular electronics and energy storage.

ASSOCIATED CONTENT Supporting Information

Methods and synthetic procedures, SEM, FTIR, solid state [START_REF] Wan | A Belt-Shaped, Blue Luminescent, and Semiconducting Covalent Organic Framework[END_REF] C NMR, TGA, BET plots, and unit cell parameters. This material is available free of charge via the internet at http://pubs.acs.org.

Scheme 1 .

 1 Scheme 1. Schematic representation of the strategy for preparing 3D-TTF-COFs a

Figure 1 .

 1 Figure 1. PXRD patterns of JUC-518 (a) and JUC-519 (b).

Figure 2 .

 2 Figure 2. Extended structures of non-interpenetrated JUC-518 (a) and 2-fold interpenetrated JUC-519 (b). C, blue; H, gray, N, red; S, yellow.

  a geometrical energy minimization by the Materials Studio software package 41 on the basis on non-or 2-fold interpenetrated pts net, their unit cell pa-rameters were acquired (a = b = 21.528 Å, c = 25.743 Å and α = β = γ = 90° for JUC-518; a = b = 18.673 Å, c = 30.679 Å and α = β = γ = 90° for JUC-519). Moreover, full profile pattern matching (Pawley) refinements were applied to their experimental PXRD patterns. Peaks at 3.78, 5.40, 7.43, 8.39, 9.44, 11.89, 14.36 and 16.57° for JUC-518 belong to the (100), (101), (002), (200), (112), (201), (320) and (303) Bragg peaks of space group P4 2 /m (No. 84); peaks at 6.51, 7.45, 9.48, 12.99, 15.19 and 16.68° for JUC-519 correspond to the (110), (

Figure 3 .

 3 Figure 3. N 2 adsorption-desorption isotherms for JUC-518 (a) and JUC-519 (b) at 77 K. Inset: pore-size distribution calculated by fitting on the NLDFT model to the adsorption data.

Figure 4 .

 4 Figure 4. Solid-state EPR spectrum of JUC-518 (a) or JUC-509 (b) before (black) and after (red) I 2 doping. Temperaturedependent I-V curves of JUC-518 (c) and JUC-509 (d) upon I 2 oxidation (black curves: pristine COFs at 25 ºC). Time-dependent electrical conductivities of JUC-518 (e) and JUC-509 (f) upon I 2 oxidation.

ACKNOWLEDGMENT

This work was supported by National Natural Science Foundation of China (21571079, 21621001, 21390394, 21571076, and 21571078), 111 project (B07016 and B17020), and the program for JLU Science and Technology Innovative Research Team. Q.F. and V.V. acknowledge the Thousand Talents program (China).

AUTHOR INFORMATION

Corresponding Author *qrfang@jlu.edu.cn

Notes

The authors declare no competing financial interests.