Valence structures of aromatic bioactive compounds: a combined theoretical and experimental study

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Title: Valence structures of aromatic bioactive compounds: a combined theoretical and experimental study
Author(s): Wickrama Arachchilage, Anoja Pushpamali; Feyer, Vitaliy; Plekan, Oksana; Iakhnenko, Marianna; Prince, Kevin C.; Wang, Feng
Abstract: Valence electronic structures of three recently isolated aryl bioactive compounds, namely 2-phenylethanol (2PE), p-hydroxyphenylethanol (HPE) and 4-hydroxybenzaldehyde (HBA), are studied using a combined theoretical and experimental method. Density functional theory-based calculations indicate that the side chains cause electron charge redistribution and therefore influence the aromaticity of the benzene derivatives. The simulated IR spectra further reveal features induced by the side chains. Solvent effects on the IR spectra are simulated using the polarizable continuum model, which exhibits enhancement of the O—H stretch vibrations with significant red-shift of 464 cm−1 in 2PE. A significant spectral peak splitting of 94 cm−1 between O(4)—H and O(8)—H of HPE is revealed in an aqueous environment. Experimental measurements for valence binding energy spectra for 2PE, HPE and HBA are presented and analyzed using outer-valence Green function calculations. The experimental (predicted) first ionization energies are measured as 9.19 (8.79), 8.47 (8.27) and 8.97 (8.82) eV for 2PE, HPE and HBA, respectively. The frontier orbitals (highest occupied molecular orbitals, HOMOs, and lowest unoccupied molecular orbitals, LUMOs) have similar atomic orbital characters although the HOMO–LUMO energy gaps are quite different.
Publication type: Journal article
Research centre: Swinburne University of Technology. Faculty of Life and Social Sciences
Source: Journal of Synchrotron Radiation, Vol. 19, no. 5 (Sep 2012), pp. 773-781
Publication year: 2012
FOR Code(s): 0205 Optical Physics; 0306 Physical Chemistry (Incl. Structural)
Keyword(s): Binding energy spectra; Bioactive compounds; Electronic structures; Experiment; Spectroscopic studies; Theory
Publisher: International Union of Crystallography
ISSN: 0909-0495
Publisher URL: http://dx.doi.org/10.1107/S0909049512026489
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