Electronic Structures and Spectroscopic Characters of Modified Oligo（alkylenedioxypyrrole）

Polyalkylenedioxypyrrole （PADOP） exhibited an excellent conductivity experimentally. A series of oligomers for the electron-rich monomer alkylenedioxypyrrole （ADOP） were designed in order to study properties of PADOP. The structures of these oligomers were optimized using density function theory （DFT） at B3LYP/6-31G（d） level. The energy gaps and thermal stabilities of the oligomers were decreased when the chain lengths were increased. These properties were also decreased with the enlargement of the neighboring substituted rings. The 13C nuclear magnetic resonance （NMR） spectra and nucleus independent chemical shifts （NICS） of the oligomers were calcu- lated at B3LYP/6-31G（d） level. The chemical shifts at J 96.! of the linking carbon atoms in the dimer of 3,4-methylenedioxypyrrole （MDOP） were moved downfield relative to those at d 89.5 of the same carbon atoms in the monomer of MDOP. The aromaticity of the central pyrrole ring in the oligomers is improved with the enlargement of the neighboring substituted rings.