title: Molecular complexes of l-phenylalanine with substituted 1,4-benzoquinones in aqueous medium: spectral and theoretical investigations.
abstract: Various spectral techniques such as UV-Vis, FT-IR, and fluorescence have been employed to investigate the charge transfer interaction of L-phenylalanine (LPA) with substituted 1,4-benzoquinones (MQ(1-4)). Kinetic and thermodynamic properties of the complexes were determined in aqueous medium at physiological condition (pH=7). The interaction of MQ(1-4) with L-phenylalanine (LPA) was found to proceed through the formation of donor-acceptor complex, yielding a radical anion. The stoichiometry of the complexes was determined by Jobs continuous variation method and was found to be 1:1 in all the cases. Fluorescence quenching studies showed that the interaction between the donor and the acceptors is spontaneous. The results indicated that the progressive replacement of chlorine atom (-I effect) by methoxy group (+M effect) in the quinone decreased the electron acceptor property of the quinone. The order of the experimentally measured association constant of these complexes was well supported by DFT/B3LYP calculations.
authors: Department of Chemistry, Gandhigram Rural Institute (Deemed University), Gandhigram 624 302, India.
authors: K
authors: K
authors: Ganesh
authors: E H
authors: EH
authors: El-Mossalamy
authors: A
authors: A
authors: Satheshkumar
authors: C
authors: C
authors: Balraj
authors: K P
authors: KP
authors: Elango
mesh_terms: D016227:Benzoquinones / Q000737:chemistry*; D002713:Chlorine / Q000737:chemistry; D010649:Phenylalanine / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water / Q000737:chemistry
chemical_list: D016227:Benzoquinones; D014867:Water; C004532:quinone; D010649:Phenylalanine; D002713:Chlorine
keywords: Charge transfer; Fluorescence; Substituent effect; Theoretical studies; l-Phenylalanine