Photoelectron Spectra, Electronic Structures, and Conformational Properties of Substituted 2-Styrylpyrroles

Abstract

The UV photoelectron spectra of three pairs of cis/trans-isomers of 2-(2-methylstyryl)pyrroles (1−6) have been recorded and analysed, making use of density functional theory (DFT) calculations at the B3LYP level. Compounds 1 and 2 have no further substituents in the pyrrole ring. In the other compounds the pyrrole ring is substituted by a methyl group in the 1-(3, 4) or 5-position (5, 6). Twisted conformations were calculated for 1−6 in which the toluene ring is generally much more distorted from the plane of the central C=C double bond than the pyrrole ring. In the cis-isomers (2, 4, 6) the torsion angle of the toluene groups amounts to about 50°,