Structure property relationships affecting the proton conductivity in imidazole loaded Al-MOFsElectronic supplementary information (ESI) available: Synthesis details, IR-, NMR- and impedance spectroscopy, thermal analyses, Rietveld refinements. See DOI: 10.1039/c6dt03048c

• Main Authors: Homburg, T, Hartwig, C, Reinsch, H, Wark, M, Stock, N
• Format: Article
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c6dt03048c

The structures of the imidazole loaded derivatives of Al-MIL-53 [Al(OH)(1,4-BDC-(CH 3 ) x )] ( x = 0, 1, 2) and CAU-11 ([Al(OH)(SDBA)]) (1,4-H 2 BDC = terephthalic acid; H 2 SDBA = 4,4′-sulfonyldibenzoic acid) were determined from powder X-ray diffraction data. Impedance spectroscopy measurements were carried out to evaluate their proton conductivities under anhydrous conditions at temperatures up to 110 °C. In Al-MIL-53-(CH 3 ) x _HIm ( x = 0, 1, 2) the formation of hydrogen bonds between the framework and the guest molecules results in a decrease in proton conductivity ( x 0 = 1.7 × 10 −6 , x 1 = 1.9 × 10 −8 and x 2 = 1.7 × 10 −9 S cm −1 at 110 °C and E act = 0.42, 0.41 and 0.46 eV, for 0, 1 and 2 CH 3 -groups, respectively). The highest conductivity has been measured for CAU-11_HIm with 3.0 × 10 −4 S cm −1 at 110 °C ( E act = 0.19 eV), where no host-guest hydrogen bonding interactions are observed. A systematic investigation on the influence of steric effects and the possibility to form host-guest interactions on the proton conductivity was carried out using imidazole loaded derivatives of Al-MIL-53 [Al(OH)(1,4-BDC-(CH 3 ) x )] ( x = 0, 1, 2) and CAU-11.