Supporting information

Nanostructuration of PEDOT in Porous Coordination
Polymers for Tunable Porosity and Conductivity
Benjamin Le Ouay,†,‡ Mickael Boudot,§ Takashi Kitao,† Takeshi Yanagida,§ Susumu
Kitagawa,†,#* and Takashi Uemura†,‡*†Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto
University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan‡
CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan§
Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga-Koen, Kasuga, Fukuoka
816-8580, Japan#Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Yoshida, Sakyo-ku, Kyoto
606-8501, Japan* uemura@sbchem.kyoto-u.ac.jp, kitagawa@icems.kyoto-u.ac.jp

Experimental section
Synthesis of MIL–101 (Cr3(BDC)3FO(H2O)2, 1)
1 was prepared using a scaled-up version of a reported procedure.1 1,4-Benzenedicarboxylicacid (H2BDC, 8.0 mmol), Cr(NO3)3•9H2O (8.0 mmol), deionized water (50 mL), and HF (48wt% solution in water, 8.0 mmol HF) were introduced in a 100 mL Teflon-lined autoclaveand heated at 220 °C for 8 h. After cooling, the resulting green powder was filtered over a
100 m grid to remove the unreacted crystals of terephthalic acid, and then isolated using a0.2 m PTFE membrane. The compound was then purified using solvothermal treatment inEtOH (3 h, 80 °C), DMF (3 h, 100 °C), and NH4F (1 M in water, 16 h, 90 °C). Samples werethen washed copiously with water and left to degas under vacuum overnight at 150 °C.
Synthesis of La(BTB) (2)2 was prepared following an adapted procedure.2 1,3,5-Benzenetrisbenzoic acid (H3BTB)
was purchased from TCI, Japan, and other reagents were purchased from Wako Chemicals,Japan. H3BTB (1.00 g, 2.27 mmol) and LaCl3•7H2O (0.843 g, 2.27 mmol) were dissolved in
an aqueous NaOH solution (0.15 mol/L, 25 mL), in a round bottom flask. After 2 min ofstirring, hot (40 °C) cyclohexanol (25 mL) was added. Reaction in the diphasic system wascarried out for 24 h under reflux and vigorous stirring. After the reaction, crystals werecollected by filtration over a PTFE membrane filter (0.2 m pore size, Advantec, Japan) andwashed thoroughly with ethanol, water, and acetone, then dried under reduced pressure atS1

150 °C.
Synthesis of PEDOT@PCP composites
1 or 2 (ca. 200 mg) was degassed in a Schlenk vial overnight at 150 °C. The desired amountof EDOT (3,4-ethylenedioxythiophene) dissolved in diethyl ether (4 mL) was introduced in
the Schlenk vial and gently stirred to homogenize the suspension of PCP. Diethyl ether wasthen removed very carefully by evacuation under reduced pressure (a progressive decrease
down to 0.3 kPa, then 0.3 kPa for 1 h). I2 (2.5 equivalents/EDOT) was then introduced in theSchlenk vial. The content of the Schlenk vial was then placed under reduced pressure (0.3kPa) before sealing, and left to react at 90 °C for 48 h. The reaction could be monitored by
the color change, from green to black. Composite powder was then rinsed copiously withmethanol, acetone, water, and then acetone until a clear filtrate was obtained, before
degassing overnight at 150 °C. Even if a significant fraction of unreacted I2 is removed uponrinsing, some more is evacuated during the degassing step, and adequate measures to trap it
should be taken.
Synthesis of PEDOT in solution
For comparison purpose, non-porous PEDOT was prepared by polymerization in solution. I2(2.23 g, 8.8 mmol) was dissolved in 25 mL toluene. EDOT (0.50 g, 3.5 mmol) was thenadded and polymerization was carried out at 90 °C for 16 h. The black precipitate was thencollected by filtration, rinsed with acetone, and degassed overnight at 150 °C under reducedpressure.
Procedure for PEDOT isolation
PEDOT was extracted by successively immersing the composite powder for 2 h in anethanolic hydrazine solution (5 vol.% hydrazine monohydrate), then for 16 h in an aqueous
NaOH solution (2 mol.L-1). The resulting dedoped PEDOT was then rinsed thoroughly withwater, and dried under vacuum at 150 °C.
Instrumental section
Powder X-ray diffractometry
PXRD diagrams were collected on a Rigaku SmartLab Diffractometer, using a Cu anode ( = 0.154 nm).
N2 adsorption measurement
N2 adsorption measurements were performed on a Belsorp II mini (BEL-Japan, Inc.).
Samples were activated at 150 °C for 16 h before the measurement.

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X-ray fluorescence
The X-ray fluorescence spectroscopy was performed using a Rigaku EDXL300 spectrometer.
Sample analysis was performed on pressure sintered pellets (5 mm, 10 MPa).
Thermo-gravimetric analysis
TGA plots were recorded using a Rigaku TG 8120. Samples were heated in an aluminumpan (500 °C, 10 °C/min) under a N2 flux (60 mL/min).

Infrared spectroscopy
Attenuated total reflection-infrared spectra were collected on a JASCO FT/IR 4200spectrometer.
Raman spectroscopy
Raman spectra were collected on a HORIBA LabRAM HR-Evolution spectrometer, usinga laser source (wavelength: 532 nm) for excitation.
MALDI-TOF
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) spectra were recorded on an ultraflex instrument (Bruker Daltonics) using TTh as thematrix.
Gel permeation chromatography
Gel permeation chromatography (GPC) measurements on the resulting polymers wereperformed in DMF at 40 °C on three linear-type polystyrene gel columns (Shodex K-805L)
that were connected to a JASCO PU-980 precision pump, a JASCO RI-930 refractive index
detector, and a JASCO UV-970 UV/vis detector set at 256 nm. The columns were calibrated
against standard polystyrene samples.
Impedance spectroscopy measurement
Samples (ca. 30 mg) were finely ground in a mortar, then pressure-sintered (10 MPa) to form
pellets (5 mm diameter, ca. 1 mm thickness). Measurements (two-electrodes set-up) were
performed using a Solartron SI 1260 phase analyzer coupled to a Solartron SI 1296 dielectricinterface.
NO2 sensing experiment
Platinum interdigitated electrodes (concentric design) on a glass substrate were obtained

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from DropSens (Spain). Sensors were prepared by grinding composite powder
1PEDOT(45) (ca. 30 mg) in ethanol (300 L) to obtain a homogeneous suspension, thendrop-casting 8 L of this suspension onto the interdigitated electrode and letting the sensor
dry at room temperature. Sensors exhibited a resistance of ca. 20 k. This value is in theideal range of our setup (100  to 1M) for an accurate chemiresistive detection as it gives
a high signal/noise ratio. This composite was selected as it was the lowest loaded in theadequate conductivity range, and thus the most porous for a high gas accessibility.
Sensors were then introduced in the sensing chambers and the resistance was monitored usinga Keithley 4200-SCS analyzer, under a measuring bias of 0.1 V. Samples were degassed
under reduced pressure (1 Pa) until stabilization of the electrical resistance. The chamber wasthen purged several times with N2 (Tomoe Shokai co., Japan) until no resistance change(attributed to grain displacement under pressure) could be observed under an inert gas
atmosphere. Sensing experiments were performed by introducing a mixture of NO2 in N2(certified at 98.7 ppm, Tomoe Shokai co., Japan) at the desired pressure inside the sensing
chamber.

EDOT
S/Cr Polymerization
aloading (%) (at.)
yield (%)b

PEDOT massfraction (%)c

I/S (at.)(PEDOT + I)
fraction in thecomposite (%)

140.19

84

10

2.00

23

25

0.36

85

18

1.43

33

45

0.63

84

270.61

36

77

1.07

83

390.74

51

101

1.40

82

450.6055

1532.228657

0.53

66

Table S1: Elemental composition of 1PEDOT, determined by XRF. aExpressed in mass
empty of 1 host. bDefined as the atomic ratio of S in the composite after washing, divided by
the amount of S introduced. cCalculated from the S/Cr ratio for a system comprising pristine
PEDOT and 1. This value is independent of the doping state, and was used for the designationof the samples. The actual mass fraction of PEDOT in the system varies depending on themass of the additional dopant.

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Figure S1: Determination of the maximum loading of EDOT in 1 by thermogravimetricanalysis. The right-hand axis corresponds to the mass of compound normalized by the massof 1. A slight excess of EDOT was introduced in 1 using the diethyl ether evacuation
technique. The TGA curve presents three decrease steps: (A) Evaporation of weakly bound
EDOT (outside 1); (B) Evacuation of the strongly bound EDOT (adsorbed in 1); (C)Decomposition of 1.

Figure S2: Thermogravimetric analysis of 1PEDOT composites. Measurements wereperformed under a N2 flux, with a heating rate of 5 °C/min. For clarity, the curves have beenrenormalized so that 100% corresponds to the composites after evacuation of adsorbed water.
As PEDOT does not decompose fully before the decomposition of 1, the determination of
the polymer content presents some incertitude. In addition, interaction between PEDOT andS5

the PCP could potentially modify the decomposition kinetics and behavior of the system (e.g.
formation of chromium sulfide instead of chromium oxide). However, under the assumptionof an identical mass loss for doped PEDOT in all composites, the mass loss obtained by TGA
are similar to the ones obtained for (PEDOT + I) calculated by XRF (cf Table S1).

Figure S3: ATR-IR spectra of several 1PEDOT composites. Spectra of host PCP 1, EDOT
monomer, and PEDOT are also represented for reference. The presence of 1 can be identified
by the presence of specific peaks that don't overlap with peaks of PEDOT. Principal peaks
are present at 1625 cm-1, 1508 cm-1, 1017 cm-1 and 750 cm-1,, in agreement with theliterature.3 Similarly, presence of oxidized PEDOT can be attested to by the presence of peaks
at 840 cm-1, 980 cm-1, 1190 cm-1, and 1350 cm-1, as identified by the literature.4

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Figure S4: MALDI-TOF spectrum of PEDOT extracted from 1PEDOT. Ionization wasperformed using a terthiophene matrix. The peaks correspond to sodium-adducts of PEDOT.
The numbers in red correspond to the polymerization degree of the associated peak. Notethat ionization may vary greatly with the PEDOT chain length and that the MALDI-TOF
spectrum may not represent accurately the chain length distribution. More specifically, theaverage molecular weight M of the sample may be underestimated as low molecular weightspecies can be more easily detected.

Figure S5: Molecular weight distribution of PEDOT extracted from 1PEDOT, obtainedby Gel Permeation Chromatography (GPC, Mn = 2960, Mw = 3560 Da, PDI = 1.2). TheS7

molecular weights were determined using polystyrene standards. Note that GPC molecularweight determination is affected by the hydrodynamic radius and thus by the rigidity of thepolymer chain. As PEDOT possess a conjugated back-bone, it is more rigid than polystyrene(which is itself considered as a rigid polymer). As a consequence, M values obtained by GPC
may be overestimated. Considering the values obtained by GPC and MALDI-TOF, we canspeculate that the PEDOT is present in the composite as chains of intermediate molecularweights.

Figure S6: Molecular dynamics (MD) structures of PEDOT chains in two adjacentnanocages of 1. (A) corresponds to 1PEDOT(10); (B) and (C) to 1PEDOT(21), observed
along two different angles, (D) to 1PEDOT(29) and (E) to 1PEDOT(13). PEDOT chainswere introduced in the PCP as octamers in (A) to (D), and as dodecamers in (E). We canS8observe that for the low loading rates, PEDOT chains interact with the cages walls and leave
the inside of the pores empty. For higher loading rates, the PEDOT chains also interact
between each other to form loosely packed clusters. The remaining porosity inside the cages
is then less well-defined.
Gray: carbon; White: hydrogen; Red: oxygen; Yellow: sulfur; Green: chromium. MD
simulations were performed using the Material Studio Modeling v8.0 software package(Accelrys Inc, San Diego, CA, USA), using the Universal Force Field, as implemented in theForcite module. The initial structure was based on the X-ray crystal structure of 1. The
quench dynamics with the optimized structures were conducted at 473 K, and then, MD
calculations were carried out at 298 K for 200 ps under NVE conditions.

Figure S7: Raman spectra of 1 and 1PEDOT(57) (excitation wavelength: 532 nm).
1PEDOT (57) shows the C=C symmetric stretching mode at 1440 cm-1, indicating thatthe dominant resonance form of PEDOT chains in 1 is the benzoid form.5 The benzoid form
reveals a coiled conformation, whereas the quinoid form is indicative of a linear
conformation.6 Thus, Raman spectroscopy suggested that PEDOT inside 1 forms a coiledstructure. This is consistent with the results of MD simulation, in which the PEDOT chains
have to coil to adopt the inner curvature of the cages of 1.

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Figure S8: X-Ray Diffractograms of 2 and 2PEDOT.

Figure S9: N2 adsorption isotherms (77 K) of 2 and 2PEDOT.

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Figure S10: Impedance diagrams of 1PEDOT (Bode representation: (A) Modulus and (B)Phase).

Figure S11: Impedance diagrams of composites of 1 with several polymers (polypyrrole,polythiophene and PEDOT). Samples were prepared by introducing the same amount ofS11

monomer in 1 (with m Loaded = m Empty PCP) before conducing the polymerization with I2 vapors.
For PEDOT, the sample corresponds to 1PEDOT(45).

Figure S12: Impedance diagrams of composites of 2PEDOT(30). 1PEDOT(27) is addedfor comparison.

Figure S13: Impedance diagrams of composites of 1PEDOT(57) as synthesized (i.e.
natively doped with non-volatile iodine species), and after exposure to iodine vapors. Theconductivity was increased only by a factor 1.7. Furthermore, the re-doped samples released
volatile I2 over time, and could not be used for gas sensing. For these reasons, we preferred
to work only with natively doped samples, as these materials didn’t release any volatile
species after evacuation at 150 °C under vacuum.

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Figure S14: Transient conductivity measurement of a sensor prepared using PEDOT
obtained from solution polymerization in Toluene, instead of 1PEDOT.

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Margiolaki, I. Science 2005, 309, 2040.
(2) Devic, T.; Serre, C.; Audebrand, N.; Marrot, J.; Férey, G. J. Am. Chem. Soc. 2005,127, 12788.
(3) Liu, Q.; Ning, L.; Zheng, S.; Tao, M.; Shi, Y.; He, Y. Sci. Rep. 2013, 3, 2916.
(4) Zhang, J.; Zhao, X. S. J. Phys. Chem. C 2012, 116, 5420.
(5) Garreau, S.; Louarn, G.; Buisson, J. P.; Froyer, G.; Lefrant, S. Macromolecules 1999,32, 6807.
(6) Tang, F.-C.; Chang, J.; Wu, F.-C.; Cheng, H.-L.; Hsu, S. L.-C.; Chen, J.-S.; Chou, W.Y. J. Mater. Chem. 2012, 22, 22409.

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