Striking effect of intra- versus intermolecular hydrogen bonding on zwitterions: physical and electronic properties.

We report the synthesis, characterization, and application of novel zwitterions. The zwitterionic structures consist of a positively charged cyanine and negatively charged dienolate moieties, confirmed by experimental observations and theoretical calculations. Single crystal X-ray studies revealed that BIT-(NPh)2 is a coplanar molecule that forms 1-D chains via π-π interactions. In contrast, BIT-(NHexyl)2 is a twisted molecule with a dihedral angle of 78° between the charged planes. In charge transport studies, thin films of the flat zwitterion show semiconducting properties, with a hole mobility of 2.1 × 10(-4) cm(2) V(-1) s(-1) while the twisted zwitterion is a high resistivity insulator.