Supporting Information

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1 Supporting Information Enhancing Proton Conduction in 2D Co-La Coordination Frameworks by Solid State Phase Transition Song-Song Bao, Kazuya Otsubo, Jared M. Taylor, Zheng Jiang, Li-Min Zheng,* Hiroshi Kitagawa* Synthesis 1,4,7-Triazacyclononane-1,4,7-triyl-tris (methylenephosphonic acid) (notph 6 ) was prepared according to the literatures [1] and the compound Co(notpH 3 ) 3H 2 O and CoLa-I have been reported in the previous work. [2] All the other starting materials were of reagent grade quality and were obtained from commercial sources without further purification. [CoLn{C 9 N 3 H 18 (PO 3 ) 2 (PO 3 H)}(H 2 O) 6 ]ClO 4 3.5H 2 O (CoLa-II). A solution of La(ClO 4 ) 3 6H 2 O (0.05 mmol, g) in water (5 ml) was added to a solution of Co(notpH 3 ) 3H 2 O (0.05 mmol, g) in water (5 ml). The solution was adjusted by 1M HClO 4 to ph 0.8 and then left at room temperature for one week to afford purple sheetlike crystals of CoLa-II in 56% (based on La). Elemental analysis calcd (%) for C 9 H 31 N 3 O 19 P 3 ClCoLa 4H 2 O: C 12.23, H 4.46, N 4.76; found: C 11.93, H 4.26, N IR (KBr, cm -1 ): 3377(br), 1652(m), 1495(w), 1468(w), 1299(w), 1251(w), 1188(w), 1149(m), 1121(s), 1105(m), 1071(w), 1003(w), 967(w), 947(w), 928(w), 780(w), 623(m), 489(w),435(w). The weight loss below 140 o C is 19.5%, close to the removal of 3.5 lattice water molecules and 6 coordinated water molecules (calcd. 20.0%). [H 3 O][CoLn{C 9 N 3 H 18 (PO 3 ) 3 }(H 2 O) 4 ]ClO 4 3H 2 O (CoLa-III). CoLa-III was prepared by exposing CoLa-II to 93% RH and 50 o C for 48 hours. Elemental analysis calcd (%) for C 9 H 29 N 3 O 18 P 3 ClCoLa 3H 2 O: C, 12.75%; H, 4.16%; N, 4.96%; found: C, 13.10%; H, 4.37%; N, 4.99%. IR (KBr, cm -1 ): 3420(br), 1633(m), 1490(w), 1470(w), 1461(w), 1296(w), 1253(w), 1174(w), 1155(w), 1151(w), 1141(w), 1121(s), 1109(w), 1072(s), 1048(s), 990(w), 963(w), 953(m), 930(w), 783(m), 625(m), 492(w). The weight loss below 140 o C is 17.9%, close to the removal of 8 water molecules (calcd. 17.0%). Sample CoLa-III-W (washed) was prepared by immersing CoLa-III in water for 10 minutes and then isolated, and the process repeated for three times. Analytical Procedures General methods: The elemental analyses were performed in a PE240C elemental analyzer. The Co, La and Cl contents were determined by the energy-dispersive X-ray spectroscopy (EDX) measurements (SEM, LEO1530 VP instrument). The infrared spectra were recorded on a Bruker Tensor 27

2 spectrometer with pressed KBr pellets. Thermal analyses were performed in nitrogen in the temperature range 30~800 o C with Al 2 O 3 pan at a heating rate of 10 o C/min on a METTLER TOLEDO TGA/DSC 1 instrument. Powder x-ray diffraction patterns were collected using a Bruker D8 ADVANCE PXRD equipped with a CuKα x-ray source. For the test of the structural stability of CoLa-I and CoLa-II under different temperatures and humidities, PXRD were performed immediately after taking out samples from temperature and humidity controller. Crystal structure determination and refinement: A single crystal of dimensions mm 3 for CoLa-II was selected for indexing and intensity data collection on a Bruker SMART APEX CCD diffractometer using graphite-monochromated Mo Kα radiation (λ = Å) at room temperature. The numbers of collected and observed independent [I > 2σ(I)] reflections are and 5113 (R int = 0.047) for CoLa-II. The data were integrated using the Siemens SAINT program. [3] Absorption corrections were applied. The structures were solved by direct methods and refined on F 2 by full-matrix least-squares using SHELXTL. [4] Anisotropic temperature factors were used for refinement of all atoms excluding hydrogen. All hydrogen atoms bound to carbon were refined using isotropic temperature factors in the riding mode; hydrogen atoms of water molecules were detected in the experimental electron density and then refined using isotropic temperature factors and reasonable restriction of O-H bond distance and H-O-H angle. Although the β angle is almost equal to 90 o (90.014(2) o ), there is no corresponding symmetry for the orthorhombic crystal system. Hence data are reduced in the monoclinic cell and subsequent refinement is carried out in P2 1 /n space group. The orientation determination of the crystal: To confirm the preferred proton-conduction path in the crystal structure, the anisotropy of the proton conductivity was evaluated by using a large single crystal. The single crystal was a purple rectangle with dimensions of 1.50 mm 0.23 mm 0.07 mm. Crystal face was determined by Bruker SAMRT APEX II and two directions (001) and (010) could be indexed. Because the upper surface was identified to be horizontal to the ab plane (perpendicular to the c axis) and β is almost equal to 90 o, hence the long side of the crystal corresponds to the a axis of structure CoLa-II. XAFS measurements and data analysis: The XAFS measurements at the Co K-edge (7709 ev) and La L3-edge (5483 ev) were carried out in transmission mode at the beamline BL14W1 in Shanghai Synchrotron Radiation Facility (SSRF) in China. The storage ring of SSRF was run at 3.5 GeV, which is the highest value in the medium-energy light source. A double crystal Si(111) monochromator was used. The Co foil and La foil standard were purchased from the commercial source. In a typical experiment, about 40.0~43.0 mg of sample (Co-K edge) or 20.0~21.0 mg of sample (La-L3 edge) was ground into fine powder and mixed with ca. 116 mg of BN and then pressed into a 13.0 mm diameter circular sample holder. The spectrum of Co foil and La foil were recorded periodically to check

3 the energy calibration. The XANES spectra were background subtracted and were normalized to the edge step at the beginning of the EXAFS oscillations in order to make a meaningful comparison of the intensity of the pre-edge features. The EXAFS signals, χ(k), were extracted from the absorption raw data, μ(e), with ATHENA program [5] choosing the energy edge value (E 0 ) at the maximum derivative. The quantitative analysis was carried out with the IFEFFIT ARTEMIS programs [6] with the atomic models described below. Theoretical EXAFS signals were computed with the FEFF7.0 code [7] using muffin-tin potentials and the Hedin-Lunqvist approximation for the 2 energy-dependent part. The free-fitting parameters used in the analysis were: S 0 (common amplitude parameter), ΔE 0 (the refinement of the edge position), R (the interatomic distance) and σ 2 (the Debye-Waller factor). The structural parameters were determined by a curve-fitting procedure in R space by using the ARTEMIS program. The employed fitting ranges are summarized in Tables S7 and S9. The intrinsic reduction factor S 2 0 was assumed to be equal to those of the standard. The coordination number N, the interatomic distance R, and the mean-square relative displacement σ 2 were fitted. The results concerning N and R are summarized in Tables S7 and S9. Humidity control: For impedance analysis, exposure of the sample to humid environments was performed for conditions at and below 95%RH using an Espec Corp. SH-221 humidity control oven. The temperature was also controlled by this oven form 15 to 65 0 C. When the samples were treated under different temperatures and humidities for PXRD meaturements, a Su-Ying Corp. GDW-100 humidity control oven was used. Impedance analysis: For compounds CoLa-I, CoLa-II and CoLa-III, AC conductivities were measured using sample pellets (2.5 mmϕ), prepared under a pressure of ~1.2 GPa. The thickness of the pellets were determined as 0.64 mm (CoLa-I) 0.62 mm (CoLa-II) and 0.62 mm (CoLa-III) respectively. Both round faces of sample pellet were treated with gold paste and then the pellets were pressed in between parallel circular titanium electrodes in specially designed porous quartz cells. The single crystal of CoLa-II was cut as size of μm 3 and the gold wires were connected to both ends of the long axis of the crystal. In general, the impedance measurements were carried out under multiple different environmental conditions by the conventional quasi-four-probe method, using gold paste and gold wires (50 µmϕ) with a Solartron SI 1260 Impedance/Gain-Phase Analyzer and 1296 Dielectric Interface in the frequency range 1 MHz 0.1 Hz. In some cases, the frequency range was 10 MHz 0.01 Hz in order to determine the first semi-circle and low-frequency tail from Nyquist plots. Data points were taken after the samples appearing to be equilibrated, with no deviation within one hour; this took on the order of half day per point. References:

4 [1] (a) Wieghard, K.; Schmid, W.; Nuber, B.; Weiss, J. Chem. Ber. 1979, 112, (b) Atkins, T. J.; Richman, J. E.; Oettle, W. F. Org. Synth. 1978, 58, 87. [2] Bao, S.-S.; Liao, Y.; Su, Y.-H.; Liang, X.; Hu, F.-C.; Sun, Z.-H.; Zheng, L.-M.; Wei, S.-Q.; Alberto, R.; Li, Y.-Z.; Ma, J. Angew. Chem. Int. Ed. 2011, 50, [3] SAINT, Program for Data Extraction and Reduction, Siemens Analytical X-ray Instruments, Madison, WI, [4] SHELXTL (version 5.0), Reference Manual, Siemens Industrial Automation, Analytical Instruments, Madison, WI, [5] Ravel, B.; Newville, M. J. Synchrotron Radiat. 2005, 12, [6] Newville, M. J. Synchrotron Radiat. 2001, 8, [7] De Leon, J. M.; Rehr, J. J.; Zabinsky, S. I.; Albers, R. C. Phys. Rev. B 1991, 44, 4146.

5 Table S1. Crystallographic data for compound CoLa-II. Compound Formular M crystal size (mm) Crystal system Space group a (Å) b (Å) c (Å) β (º) V (Å -3 ) Z D c (g cm -3 ) μ (mm -1 ) F(000) R int T max, T min Goodness-of-fit on F 2 R 1, wr 2 [I>2σ(I)] R 1, wr 2 (all data) (Δρ) max, (Δρ) min (e Å -3 ) CoLa-II C 9 H 41 N 3 P 3 O 24 ClCoLa Monoclinic P2 1 /n (10) (3) (12) (2) (5) , , , , -0.94

6 Table S2. Selected bond lengths (Å) and angles ( ) for CoLa-II. Co(1)-O(1) 1.932(3) La(1)-O(8B) 2.500(3) P(1)-O(2) 1.506(3) Co(1)-O(4) 1.976(3) La(1)-O(1W) 2.587(3) P(1)-O(3) 1.518(3) Co(1)-O(7) 1.926(3) La(1)-O(2W) 2.664(3) P(2)-O(4) 1.547(3) Co(1)-N(1) 1.946(3) La(1)-O(3W) 2.593(3) P(2)-O(5) 1.487(3) Co(1)-N(2) 1.944(3) La(1)-O(4W) 2.603(3) P(2)-O(6) 1.538(3) Co(1)-N(3) 1.962(3) La(1)-O(5W) 2.656(3) P(3)-O(7) 1.537(3) La(1)-O(2) 2.476(3) La(1)-O(6W) 2.561(3) P(3)-O(8) 1.484(3) La(1)-O(5A) 2.463(3) P(1)-O(1) 1.549(3) P(3)-O(9) 1.541(3) O(1)-Co(1)-O(4) 89.62(12) O(2)-La(1)-O(5W) (10) O(1)-Co(1)-O(7) 90.03(13) O(2)-La(1)-O(6W) (10) O(4)-Co(1)-O(7) 92.33(12) O(2)-La(1)-O(5A) 92.78(10) O(1)-Co(1)-N(1) 89.82(13) O(2)-La(1)-O(8B) (10) O(1)-Co(1)-N(2) 92.80(13) O(2W)-La(1)-O(3W) 67.66(10) O(1)-Co(1)-N(3) (13) O(2W)-La(1)-O(4W) (10) O(4)-Co(1)-N(1) (13) O(2W)-La(1)-O(5W) (9) O(4)-Co(1)-N(2) 88.35(13) O(2W)-La(1)-O(6W) 88.03(10) O(4)-Co(1)-N(3) 92.89(13) O(2W)-La(1)-O(5A) (10) O(7)-Co(1)-N(1) 91.25(13) O(2W)-La(1)-O(8B) 68.37(9) O(7)-Co(1)-N(2) (14) O(3W)-La(1)-O(4W) 69.61(10) O(7)-Co(1)-N(3) 88.70(13) O(3W)-La(1)-O(5W) 93.13(10) N(1)-Co(1)-N(2) 88.10(14) O(3W)-La(1)-O(6W) (10) N(1)-Co(1)-N(3) 88.10(14) O(3W)-La(1)-O(5A) (10) N(2)-Co(1)-N(3) 87.75(14) O(3W)-La(1)-O(8B) 71.91(10) O(1W)-La(1)-O(2) 67.22(10) O(4W)-La(1)-O(5W) 63.60(10) O(1W)-La(1)-O(2W) 65.35(10) O(4W)-La(1)-O(6W) (11) O(1W)-La(1)-O(3W) (11) O(4W)-La(1)-O(5A) 78.19(10) O(1W)-La(1)-O(4W) (10) O(4W)-La(1)-O(8B) (10) O(1W)-La(1)-O(5W) (10) O(5W)-La(1)-O(6W) 82.08(10) O(1W)-La(1)-O(6W) 67.04(11) O(5A)-La(1)-O(5W) 73.08(9) O(1W)-La(1)-O(5A) 76.47(10) O(5W)-La(1)-O(8B) 68.73(9) O(1W)-La(1)-O(8B) (10) O(5A)-La(1)-O(6W) 69.44(10) O(2)-La(1)-O(2W) 79.97(9) O(6W)-La(1)-O(8B) 68.20(10) O(2)-La(1)-O(3W) 76.25(10) O(5A)-La(1)-O(8B) (9) O(2)-La(1)-O(4W) 71.61(10) Symmetry transformations used to generate equivalent atoms: A: 1+x, y, z, -z+1/2; B: 1/2+x, 1/2-y, -1/2+z.

7 Table S3. Cell parameters of CoLa-II samples were obtained by Pawley fitting on the powder X-ray diffraction pattern using Topas 4.2 program. Powde 40%RH 50%RH 60%RH 70%RH 80%RH 90%RH 93%RH r a (Å) b (Å) c (Å) β ( ) V (Å 3 ) Table S4. Cell parameters of CoLa-I and CoLa-III were obtained by Pawley fitting on the powder X-ray diffraction pattern using Topas 4.2 program. CoLa-I CoLa-III Cell P2 1 /c P2 1 /c a (Å) b (Å) c (Å) β ( ) V (Å 3 ) Table S5. Selected hkl and 2θ values of CoLa-I, CoLa-II and CoLa-III ( a relative intensity). CoLa-I CoLa-III CoLa-II hkl 2θ I a hkl 2θ I a hkl 2θ I a

8 Table S6. EDX analysis of CoLa-I, CoLa-II, CoLa-III, CoLa-III-W (washed) and Co(notpH 3 ). CoLa-I CoLa-II CoLa-III CoLa-III-W Co(notpH 3 ) Element Wt% At% Wt% At% Wt% At% Wt% At% Wt% At% C N O P Cl La Co total Table S7. Local structural fitting parameters of the Co-N and Co-O shells around Co in CoLa-I, CoLa-II, CoLa-III and Co(notpH 3 ). 2 Samples Shell R N S 0 ΔE 0 σ 2 R-factor Co-O 1.94(2) (35) (5) CoLa-I Co-N 1.92(2) (9) (6) CoLa-II CoLa-III Co(notpH 3 ) Co-O 1.96(1) (20) (3) Co-N 1.92(2) (8) (2) Co-O 1.94(1) (9) (3) Co-N 1.92(2) (11) (3) Co-O 1.95(1) (22) (2) Co-N 1.91(1) (7) (2)

9 Table S8. Forward Fourier Transform and backward Fourier Transform selected parameters of the Co-N/O first shell at Co-K edge. Samples Shell K-range Window type R-range Window type CoLa-I Co-O/N 2.58~13.00 Kaiser-Bessel 1.02~1.80 hanning CoLa-II Co-O/N 2.58~13.00 Kaiser-Bessel 1.02~1.80 hanning CoLa-III Co-O/N 2.58~13.00 Kaiser-Bessel 1.02~1.80 hanning Co(notpH 3 ) Co-O/N 2.58~13.00 Kaiser-Bessel 1.02~1.80 hanning Table S9. Local structural fitting parameters of the La-O shells around La in CoLa-I, CoLa-II, CoLa-III and CoLa-III-W (washed). Samples Shell R N S 0 2 ΔE 0 σ 2 C3 R-factor CoLa-I La-O 2.55(7) (39) 0.015(1) (13) CoLa-II La-O 2.59(4) (25) 0.012(1) (9) CoLa-III La-O 2.59(7) (68) 0.013(1) (2) CoLa-III-W La-O 2.58(7) (80) 0.016(1) (2) Table S10. Forward Fourier Transform and backward Fourier Transform selected parameters of the La-O first shell at La-L 3 edge. Samples Shell K-range Window type R-range Window type CoLa-I La-O 2.68~9.08 hanning 1.45~2.36 hanning CoLa-II La-O 2.68~9.08 hanning 1.45~2.36 hanning CoLa-III La-O 2.68~9.08 hanning 1.45~2.36 hanning CoLa-III-W La-O 2.68~9.08 hanning 1.45~2.36 hanning

10 Figure S1. Building unit of CoLa-I (left) and CoLa-II (right) with the atomic labeling scheme (50% probability). Figure S2. The layer structures of CoLa-I (left) and CoLa-II (right). Figure S3. 2D H-bond network in ab plane in CoLa-I (left) and 1D H-bond chain along the a axis in CoLa-II (right). The H-bonds between phosphonate groups and coordinated water molecules are omitted for clarity.

11 Figure S4. TG analyses of the powder samples of CoLa-I (left) and CoLa-II (right). Figure S5. TG analysis of CoLa-III.

12 Figure S6. Pawley fit of powder samples of CoLa-I, CoLa-II and CoLa-III performed using Topas 4.2 program. Figure S7. The PXRD patterns of CoLa-I at different humiditites at 25 o C. Each sample was kept in humidity controller for 20 hours before measurements.

13 d 002 (Å) RH % Figure S8. The enlargement view of the PXRD patterns of CoLa-I at different humidities at 25 o C (top); the plots of d 002 vs. relative humidity for CoLa-I at 25 0 C (bottom). Each sample was kept in humidity controller for 20 hours before XRD measurements.

14 5000 at 93% RH 4000 Intensity C θ Figure S9. The enlargement view of the XRD pattern of CoLa-I at various temperature at 93% RH. Each sample was kept in humidity controller for 20 hours before XRD measurements.

15 Figure S10. The PXRD patterns of CoLa-II at different humidity at 25 o C. Each sample was kept in humidity controller for 20 hours before measurements at 93% RH 25 C Intensity appears CoLa-III CoLa-I appears phase θ ( o ) Figure S11. The XRD pattern of CoLa-II at various temperatures at 93% relative humidity. Each sample was kept in humidity controller for 20 hours before XRD measurements.

16 Figure S12. The IR spectra of compound CoLa-I, CoLa-II, CoLa-III and CoLa-III-W (washed) (top: full range; bottom: PO 3 2- and ClO 4 - region).

17 Figure S13. Calculated La:Co:Cl atomic ratio from EDX analyses of different samples.

18 Figure S14. EDX spectra of CoLa-I, CoLa-II, CoLa-III, CoLa-III-W and Co(notpH 3 ).

19 Figure S15. Co K-edge XANES spectra of CoLa-I, CoLa-II, CoLa-III and Co(notpH 3 ). The normalized curves are overlapping for samples CoLa-I, CoLa-II and CoLa-III, indicating that the coordination environment of Co 3+ ion is almost the same in the three cases. Figure S16. La L3-edge XANES spectra of CoLa-I, CoLa-II, CoLa-III and CoLa-III-W. The normalized curves of CoLa-I and CoLa-III are superimposed. While the height of the main peak at ev in CoLa-II is significantly larger, attributed to the {LaO 9 } coordination sphere in CoLa-II instead of a {LaO 8 } sphere as in CoLa-I.

20 Figure S17. XAFS normalization (top) and Co K-edge k 3 -weight EXAFS signals (bottom) of CoLa-I, CoLa-II, CoLa-III and Co(notpH 3 ).

21 Figure S18. XAFS normalization (top) and La L3-edge k 2 -weight EXAFS signals (bottom) of CoLa-I, CoLa-II, CoLa-III and CoLa-III-W.

22 Figure S19. Fourier transformed space (R space) of CoLa-I, CoLa-II, CoLa-III and Co(notpH 3 ) at Co K-edge (solid line) and their fitting curves of the first shell (hollow triangle). Figure S20. Fourier transformed space (R space) of CoLa-I, CoLa-II, CoLa-III and CoLa-III-W at La L 3 -edge (solid line) and their fitting curves of the first shell (hollow triangle).

23 Figure S21. The PXRD patterns of CoLa-I and CoLa-II before and after (CoLa-Ia, CoLa-IIa) water adsorption and desorption isotherms at 25 o C. The samples were pretreated at 100 o C under vacuum for two hours. Figure S22. A large single crystal of CoLa-II was selected and determined crystal face by X-ray diffraction.

24 Figure S23. Nyquist plots exemplified by sample CoLa-I, CoLa-II, CoLa-III and CoLa-II-SC at 95% RH and 25 o C (1 MHz to 0.1 Hz).

25 (a) (b) (c) Figure S24. Nyquist plots for CoLa-I at 25 o C and various RH. (a) RH increases from 40 to 95%; (b) The enlargement view of graph (a); (c) RH decreases from 95 to 60%.

26 (a) (b) (c)

27 (d) Figure S25. Nyquist plots for CoLa-II at 25 o C and various RH. (a) RH increases from 40 to 95%; (b) The enlargement view of graph (a); (c) RH decreases from 95 to 60%; (d) The enlargement view of graph (c).

28 (a) (b) (c) Figure S26. Nyquist plots for CoLa-III at 25 o C and various RH. (a) RH increases from 40 to 95%; (b) The enlargement view of graph (a); (c) RH decreases from 95 to 60%.

29 (a) (b) (c) Figure S27. Nyquist plots for CoLa-II-SC at 25 o C and various RH. (a) RH increases from 50 to 95%; (b) The enlargement view of graph (a); (c) RH decreases from 95 to 60%.

30 Figure S28. Nyquist plots for CoLa-I at 95% RH and various temperatures ( o C). Figure S29. Nyquist plots for CoLa-III at 95% RH and various temperatures ( o C).

31 Figure S30. Nyquist plots for CoLa-II-SC at 95% RH and various temperatures ( o C). Figure S31. (a) Nyquist plots for CoLa-III-W (washed) at 95% RH and various temperatures; (b) Plots of log(σt) vs. 1000/T at 95% RH for CoLa-I and CoLa-III-W. The solid lines represent the best fits of the data.