Highly Luminescent and Semiconducting Supramolecular Organic Charge Transfer Complex Generated via H-Bonding Interaction Pathway

The construction of a charge transfer (CT) organic material with important electrical properties is demonstrated where the charge transfer state is generated via delocalization through H-bonding interaction pathway. The reaction of simple organic molecule pyromellitic acid with orthophenylene diamine in 1:2 ratios gives a colorless cocrystal 1'. The rare transition phenomena of a colorless cocrystal 1' to an orange charge transfer state 1 take place in methanol water media over several days. The charge transfer state is isolated as orange single crystals of 1 which show semiconducting as well as fluorescent properties. The X-ray diffraction analysis of 1 demonstrates the formation of charge separated extended H-bonded network which is supposed to be solely responsible for the delocalization of charge in the system. This is the first example of formation of donor-acceptor-based charge transfer material constructed by just tuning the H-bond distance of a colorless cocrystalline state with non-chalcogen and non-halogenated molecules.