Acta Chimica Slovaca (ACS) publishes papers on fundamental and applied aspects of chemistry, biochemistry, chemical technology, chemical engineering and process control, biotechnology and food technology. Welcome are also topics which include chemical aspects of materials, physical chemistry and chemical physics, analytical chemistry, macromolecular chemistry and biomedical engineering.

Theoretical study of 2-phenylpyrrole molecule using various quantum-chemical approaches

Lenka Rottmannová *, Kraiwan Punyain a, Ján Rimarčík, Vladimír Lukeš, Erik Klein, Anne-Marie Kelterer b

Institute of Physical Chemistry and Chemical Physics, Slovak University of Technology in Bratislava, Radlinského 9, SK-812 37 Bratislava, Slovak Republic
a Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremayrgasse 9/I, A-8010 Graz, Austria
b Institute of Physical and Theoretical Chemistry, Graz University of Technology, Stremayrgasse 9/I, A-8010 Graz, Austria

E-mail: *

Abstract: A systematic theoretical study of 2-phenylpyrrole (PhPy) is presented for its neutral and monocharged states. The calculations were performed using the semiempirical Austin Model 1 (AM1) method, ab initio MØller-Plesset perturbation theory up to the second-order (MP2), density functional theory (DFT) and its tight-binding approximation (DFTB+). The comparison of the obtained equilibrium geometries showed that the C—C bond lengths in the phenylene ring are practically identical for the neutral state. Electric charging leads to significant changes in the geometry with respect to the neutral state. The C—N bonds in PhPy are elongated and the negative charging produces the out-of-plane distortion of N—H bond from the aromatic ring plane. The anionic state of the investigated molecule is connected with a higher perturbation of bond length alternation in both rings in comparison to the cationic state. The vibrationaly broadened absorption spectra, based on the on-the-fly molecular dynamics (MD) simulations, are also presented and compared with experimental spectra. Although the DFTB+ method has the tendency to planarize the investigated molecular structure, the agreement of simulated absorption spectra based on the MD DFTB+ geometries with TD-DFT calculations is acceptable.

Keywords: DFT, electro-optical properties, charged states, MP2, absorption spectra simulations

Full paper in Portable Document Format: acs_0104.pdf

Acta Chimica Slovaca, Vol. 5, No. 1, 2012, pp. 21—28