Conjugated crosslinks boost the conductivity and stability of a single crystalline metal-organic framework

A linker molecule with four pendant thiophene functions was crystallized with Zr(IV) ions to forma semiconductive porous coordination solid (1.1 x 10(-5) S cm(-1)). Oxidative treatment with FeCl3 guests then coupled the thiophene units to form conjugated bridges as covalent crosslinks. The resulting hybrid of a metal-organic framework and conjugated polymer featured robust crystalline order that withstood long-term air exposure and broad pH (from 0 to 12) conditions. Moreover, the homocoupled thiophene units, conjugated through sulfide links (-S-) with the linker backbone, afforded higher electronic conductivity (e.g., >2.2 x 10(-3) S cm(-1)), which is characteristic of conductive polymer prototypes of polythiophene and polyphenylene sulfide. The crosslinked solid also exhibited proton conductivity that could be increased broadly upon H2SO4 treatment (e.g., from 5.0 x 10(-7) to 1.6 x 10(-3) S cm(-1)).

Automated summary

A linker molecule with thiophene functions was crystallized with Zr(IV) ions to form a semiconductive porous coordination solid, which was further treated to covalently link thiophene units and improve electronic conductivity and proton conductivity.