Tuning Proton Conduction in Metal-Organic Frameworks

Date
2017
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Proton conductivity was explored in an organosulfonate and three organophosphonate based metal-organic frameworks (MOFs). The MOFs synthesized closely resembled a number of previously reported structures allowing for comparison between structure and property. Modifications to the MOFs resulted in significant differences in their properties relative to the reported derivatives. The first MOF discussed utilized Cs+ and 2,4,6-trihydroxy-1,3,5-benzenetrisulfonic acid to form a highly connected framework, Cs3PGS·3H2O. Owing to the large, polarizable cation and thus dynamic nature, the MOF achieved a maximum proton conductivity of 1.1x10-5 Scm-1 at 70°C, 50% relative humidity (RH). The second MOF, utilizing Cu2+ and 1,3,5-benzenetriphosphonic acid yielded Cu-BTP, a layered structure with hydrated interlayer. The robustness of Cu-BTP was explored for proton conduction and allowed hydration level, structure and proton conductivity to be explored together. Proton conductivity in CuBTP reached 7.0 x 10-5 Scm-1 at 85°C, 98% RH. The third MOF, formed by a series of trivalent lanthanides (Ce, Pr, Nd, Sm, Eu, Gd) and 1,2,4,5-tetrakisphosphonomethyl benzene, explored the lanthanide contraction effect, to which the Pr3+ derivative resulted in the maximum conductivity of 3.9x10-3 Scm-1 at 85°C, 95% RH. This high conductivity was achieved due to the contraction effect on the growth of particles. Finally, anion substitution in a Zr-phosphate-phosphonate MOF, using the ligand bis(2-phosphonoethyl)-4,4’-bipyridinium dibromide, enabled control over the proton conductivity. The substitution of HSO4- for F- anions content and conductivity were explored. In all four projects, the MOFs were crystalline and enabled structure-property relationships to be established.
Description
Keywords
Chemistry--Inorganic, Chemistry--Physical, Materials Science
Citation
Wong, N. (2017). Tuning Proton Conduction in Metal-Organic Frameworks (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/28533