Multi electron and proton-transfer system based on 2,2′-biimidazole derivatives

A systematical study of 2,2′-biimidazole (H2BIM) derivatives proved that these compounds form a new proton-transfer(PT) and electron (charge)-transfer(CT) system. The study of their acidity, redox property and complex formation with TCNQs confirmed seven new states in the speculated 25-independent species. Corresponding to the protonated states of H2BIM system, the formal charges of TCNQs in the complexes vary from completely ionic, partial CT, to neutral. Also, we developed a new method of electrocrystallization using the pH-controlled electrolytic solution. By applying this novel technique, dibenzobiimidazole system gave metallic to semiconductive TCNQ complexes.