Dynamic Self-Assembly of Charge-Transfer Nanofibers of Tetrathiafulvalene Derivatives with F4TCNQ

Abstract

One‐dimensional charge‐transfer nanostructures were constructed by the supramolecular coassembly of amphiphilic (Amph‐TTF) and hydrophobic (TDD‐TTF) tetrathiafulvalene (TTF) donor derivatives with the acceptor 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4TCNQ), in appropriate solvent composition mixtures. Microscopic analyses show that TDD‐TTF retains its self‐assembled fibrillar morphology even in the charge‐transfer state, whereas Amph‐TTF undergoes a spherical to nanorod transition upon coassembly. Time‐dependent optical spectroscopy studies have shown a spontaneous change in molecular organization in TDD‐TTF‐based donor–acceptor costacks, which suggests a dynamic behavior, in contrast to the kinetically stable amphiphilic TTF assemblies. We have also tried to get an insight into the observed time‐dependent change in molecular packing of these nanostructures through spectroscopic analyses by commenting on whether the TTF–TCNQ pair is cofacially arranged or present in the classical herringbone (orthogonal) fashion. Furthermore, our two‐probe electrical measurements showed that these charge‐transfer fibers are conducting. A supramolecular approach that yields 1D charge‐transfer nanostructures of donor and acceptor molecules will be an alternative to existing crystalline substances with high conductivity and hence can be a viable tool for nanoelectronics.