Tuning Electrical- and Photo-Conductivity by Cation Exchange within a Redox-Active Tetrathiafulvalene-Based Metal-Organic Framework

To activate electronic and optical functions of the redox-active metal-organic framework, (Me2NH2)[In-III(TTFTB)].0.7 C2H5OH.DMF (Me2NH2@1, TTFTB=tetrathiafulvalene-tetrabenzoate, DMF=N,N-dimethylformamide), has been exchanged by tetrathiafulvalenium (TTF.+) andN,N '-dimethyl-4,4 '-bipyridinium (MV2+). These cations provide electron carriers and photosensitivity. The exchange retains the crystallinity allowing single-crystal to single-crystal post-synthetic transformation to TTF@1and MV@1. Both TTF(.+)and MV(2+)enhance the electrical conductivity by a factor of 10(2)and the visible light induced photocurrent by 4 and 28 times, respectively. EPR evidences synergetic effect involving charge transfer between the framework redox-active TTFTB bridges and MV2+. The results demonstrate that functionalization of MOF by cation exchange without perturbing the crystallinity extends possibilities to achieve switchable materials.