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Comparative theoretical study of the UV/Vis absorption spectra of styrylpyridine compounds using TD-DFT calculations.
MedLine Citation:
PMID:  23053012     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
This study examined absorption properties of 2-styrylpyridine, trans-2-(m-cyanostyryl)pyridine, trans-2-[3-methyl-(m-cyanostyryl)]pyridine, and trans-4-(m-cyanostyryl)pyridine compounds based on theoretical UV/Vis spectra, with comparisons between time-dependent density functional theory (TD-DFT) using B3LYP, PBE0, and LC-ωPBE functionals. Basis sets 6-31G(d), 6-31G(d,p), 6-31+G(d,p), and 6-311+G(d,p) were tested to compare molecular orbital energy values, gap energies, and maxima absorption wavelengths. UV/Vis spectra were calculated from fully optimized geometry in B3LYP/6-311+G(d,p) in gas phase and using the IEFPCM model. B3LYP/6-311+G(d,p) provided the most stable form, a planar structure with parameters close to 2-styrylpyridine X-ray data. Isomeric structures were evaluated by full geometry optimization using the same theory level. Similar energetic values were found: ∼4.5 kJ mol(-1) for 2-styrylpyridine and ∼1 kJ mol(-1) for derivative compound isomers. The 2-styrylpyridine isomeric structure differed at the pyridine group N-atom position; structures considered for the other compounds had the cyano group attached to the phenyl ring m-position equivalent. The energy difference was almost negligible between m-cyano-substituted molecules, but high energy barriers existed for cyano-substituted phenyl ring torsion. TD-DFT appeared to be robust and accurate approach. The B3LYP functional with the 6-31G(d) basis set produced the most reliable λ(max) values, with mean errors of 0.5 and 12 nm respect to experimental values, in gas and solution, respectively. The present data describes effects on the λ(max) changes in the UV/Vis absorption spectra of the electron acceptor cyano substituent on the phenyl ring, the electron donor methyl substituent, and the N-atom position on the electron acceptor pyridine ring, causing slight changes respect to the 2-styrylpyridine title compound.
Authors:
Maria Eugenia Castro; M Judith Percino; Victor M Chapela; Guillermo Soriano-Moro; Margarita Ceron; Francisco J Melendez
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-10-11
Journal Detail:
Title:  Journal of molecular modeling     Volume:  -     ISSN:  0948-5023     ISO Abbreviation:  J Mol Model     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-11     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9806569     Medline TA:  J Mol Model     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Centro de Química, Instituto de Ciencias, Universidad Autónoma de Puebla, Complejo de Ciencias, ICUAP, Edif. 103 F, 22 Sur y San Claudio, Ciudad Universitaria, Puebla, Pue, 72570, Mexico.
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