DFT calculations and electronic absorption spectra of some, α- and γ-pyrone derivatives
Hassan, Walid M I; Moustafa, Hussein; Hamed, Mohamed N H; Laila I. Ali; Halim, Shimaa Abdel;
Abstract
The electronic absorption spectra of 6-ethyl-4-hydroxy-2,5-dioxo-pyrano[3,2-c] quinoline 1, 6-ethyl-4-hydroxy-3-nitro-2,5-dioxo-pyrano[3,2-c] quinoline 2, 6-ethyl-4-chloro-2,5-dioxo-pyrano[3,2-c] quinoline 3, 6-ethyl-3-nitro-4-chloro-2,5-dioxo-pyrano[3,2-c] quinoline 4, 6-ethyl-4,5-dioxopyrano[3,2-c] quinoline 5, and 6-ethyl-3-nitro-6H-pyrano [3,2-c]quinoline-4,5-dione 6, were measured in polar (methanol) as well as nonpolar (dioxane) solvents. The geometries were optimized using B3LYB/6-311G (p,d) method. The most stable geometry of the studied compounds, 1-6, is the planar structure as indicates by the values of the dihedral angles. The insertion of a nitro group in position 3 in both α- and γ-pyrone ring decreases the energy gap and hence increases the reactivity of 3 and 6 compounds. Assignment of the observed bands as localized, delocalized and/or of charge transfer (CT) has been facilitated by TD-DFT calculations. The correspondences between the calculated and experimental transition energies are satisfactory. The solvent and substituent effects have been investigated. Chloro-substituent has a higher band position and intensity effects on the spectra more than hydroxyl or nitro groups.
Other data
Title | DFT calculations and electronic absorption spectra of some, α- and γ-pyrone derivatives | Authors | Hassan, Walid M I; Moustafa, Hussein; Hamed, Mohamed N H; Laila I. Ali ; Halim, Shimaa Abdel | Keywords | Alpha and gamma pyrone derivatives; MO-calculations; Solvent effect; TD-DFT; UV spectra | Issue Date | 3-Jan-2014 | Publisher | PERGAMON-ELSEVIER SCIENCE LTD | Journal | Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | ISSN | 1386-1425 | DOI | 10.1016/j.saa.2013.09.057 | PubMed ID | 24103229 | Scopus ID | 2-s2.0-84884940729 | Web of science ID | WOS:000328179900077 |
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