Charge-Transfer Nanostructures through Noncovalent Amphiphilic Self-Assembly: Extended Cofacial Donor-Acceptor Arrays

Abstract

Charge‐transfer (CT) assemblies with mixed‐stack (MS) arrays of donor (D) and acceptor (A) molecules are important class of functional organic materials owing to their interesting optoelectronic properties. Construction of charge‐transfer nanostructures comprising cofacially stacked perylene/tetrathiafulvalene (TTF) donors and viologen acceptors by an efficient, noncovalent, amphiphilic approach is described. Optical properties were used to probe the CT coassembly and stoichiometry of molecular D/A components, whereas 1H NMR and X‐ray diffraction studies provided insights into their face‐to‐face organization. The efficient equimolar coassembly between ionic D (perylene salt (PS) and TTF salt (TTFS)) and A (dodecylmethyl viologen (DMV) and hexadecylmethyl viologen (HDMV)) molecules in water through ground state CT interactions results in the formation of noncovalent amphiphiles. Microscopic studies provided structural insight into the hierarchical organization of these charge‐transfer D‐A amphiphiles into bilayers and one‐dimensional nanostructures. In addition, at higher concentrations PS‐HDMV amphiphiles form hydrogels due to strong hydrophobic interactions caused by the long hydrocarbon tails. Two probe devices fabricated from these CT nanostructures as channel elements showed impressive conductivity values without any external doping, thus validating the CT design for conducting organic wires.