An Electrically Conductive Tetrathiafulvalene-Based Hydrogen-Bonded Organic Framework

Recent advancements in the development of conductive metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) have sparked interest in a variety of applications that leverage electronic materials due to the inherent tunability, porosity, and crystallinity associated with these materials. Hydrogen-bonded organic frameworks (HOFs) comprise an emerging class of complementary porous materials that assemble crystalline networks mainly from intermolecular hydrogen-bonding interactions; however, relatively few reports on functional HOFs exist as these reversible interactions are much weaker than the coordination or covalent bonds found in the former frameworks, which presents additional challenges in the isolation and activation of HOFs. In this work, we introduce an approach to access a permanently porous HOF derived from a tetrathiafulvalene (TTF) core, which is the first HOF reported to date that exhibits electrical conductivity. Upon precipitation from solution, HOF-110 self-assembles in a preferred orientation that contains vertical columns of TTF dimers, and the postsynthetic incorporation of iodine within the nanoporous channels of this framework affords pressed pellet conductivity values of up to 6.0 × 10–7 S·cm–1, which is an almost 30-fold improvement compared with pressed pellets of the pristine framework. Extensive structural characterization studies suggest the presence of radical mixed-valence TTF/TTF·+ species within these materials, which is consistent with previous reports on analogous TTF-based MOFs and COFs. Overall, this work presents a viable strategy to develop robust, electrically conductive frameworks built from purely intermolecular interactions, further expanding the toolbox available for the assembly of functional porous materials.