Theoretical Studies on the Electronic Spectra of Isomeric Bifurans, Bipyrroles, Bithiophenes, Thienylfurans, Thienylpyrroles, and Furylpyrroles

Abstract Bifurans (I-III), bipyrroles (IV-VI), bithiophenes (VII-IX), thienylfurans (X-XIII), thienylpyrroles (XIV-XVII), and furylpyrroles (XVIII-XXI) are isomeric biheterocycles formed from two five-membered ring systems (furan, pyrrole, thiophene) linked together by an essential single bond (∼1.47 Å).