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, (Me 2 NH 2 )[In III (TTFTB)]⋅0.7 C 2 H 5 OH⋅DMF (Me 2 NH 2 @ 1 , TTFTB=tetrathiafulvalene‐tetrabenzoate, DMF= N , N ‐dimethylformamide), has been exchanged by tetrathiafulvalenium (TTF .+ ) and N , N ′‐dimethyl‐4,4′‐bipyridinium (MV 2+ ). These cations provide electron carriers and photosensitivity. The exchange retains the crystallinity allowing single‐crystal to single‐crystal post‐synthetic transformation to TTF@ 1 and 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 MV 2+ . The results demonstrate that functionalization of MOF by cation exchange without perturbing the crystallinity extends possibilities to achieve switchable materials.