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

• Published in: Angewandte Chemie International Edition Vol. 59; no. 42; pp. 18763 - 18767
• Main Authors: Zhou, Yan, Yu, Fei, Su, Jian, Kurmoo, Mohamedally, Zuo, Jing‐Lin
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 12.10.2020
• Edition: International ed. in English
• Subjects: Cation exchange; Cation exchanging; Cations; Charge transfer; Crystal structure; Crystallinity; Dimethylformamide; Electric bridges; Electrical conductivity; Electrical resistivity; Metal-organic frameworks; methylviologen; Photoelectric effect; Photoelectric emission; Photosensitivity; post-synthetic modification; redox-active species; single-crystal to single-crystal transformation; tetrathiafulvalene; post-synthetic modification; redox-active species; methylviologen; single-crystal to single-crystal transformation; tetrathiafulvalene
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202008941

To activate electronic and optical functions of the redox‐active metal–organic framework, (Me2NH2)[InIII(TTFTB)]⋅0.7 C2H5OH⋅DMF (Me2NH2@1, TTFTB=tetrathiafulvalene‐tetrabenzoate, DMF=N,N‐dimethylformamide), has been exchanged by tetrathiafulvalenium (TTF.+) and N,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@1 and MV@1. Both TTF.+ and MV2+ enhance the electrical conductivity by a factor of 102 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. By employing a single‐crystal‐to‐single‐crystal post‐synthetic transformation, electrical‐ and photo‐conductivity were activated by cation exchanges of dimethylammonium with tetrathiafulvalenium (TTF.+) and N,N′‐dimethyl‐4,4′‐bipyridinium (MV2+) into a redox‐active metal–organic framework containing TTF‐tetrabenzoate, (Me2NH2)[InIII(TTFTB)]⋅0.7 C2H5OH⋅DMF.