title: Theoretical investigations of the structures and electronic spectra of 8-hydroxylquinoline derivatives.
abstract: The spectroscopic properties of 8-hydroxyquinoline derivatives are theoretically investigated by means of density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods. The target molecules are divided into two groups: group (I): (E)-2-(2-(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)vinyl)quinolin-8-ol (A), together with corresponding potential reaction products of A with acetic acid, i.e., (E)-2-(2-(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)vinyl)quinolin-8-yl acetate (AR1), and (E)-2-(2-(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)vinyl)-8-hydroxyquinolinium (AR2); group (II): (E)-2-(2-(1-(4-chlorophenyl)-3,5-dimethyl-1H-pyrazol-4-yl)vinyl)quinolin-8-ol (B), as well as potential reaction products of B with acetic acid, i.e., (E)-2-(2-(1-(4-chlorophenyl)-3,5-dimethyl-1H-pyrazol-4-yl)vinyl)quinolin-8-yl acetate (BR1), and (E)-2-(2-(1-(4-chlorophenyl)-3,5-dimethyl-1H-pyrazol-4-yl)vinyl)-8-hydroxyquinolinium (BR2). The geometries are optimized by B3LYP and M06 methods. The results indicate that product molecules tend to be effectively planar compared with reactants. Subsequently, UV absorption spectra are simulated through TD-DFT method with PCM model to further confirm the reasonable products of two reactions. AR2 and BR2 are identified as the target molecules through the experimental spectra for the real products. It is worth noting that the maximum absorption wavelengths of compounds AR2 and BR2 present prominent red shift compared the initial reactants A and B, respectively, which should be ascribed to the enhancive planarity of products that mentioned above and the decreased HOMO-LUMO energy gap. Geometric structures and optical properties for corresponding compounds are discussed in detail.
authors.affiliation: Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004, China.
authors.forename: Pan
authors.initials: P
authors.lastname: Ning
authors.forename: Tiegang
authors.initials: T
authors.lastname: Ren
authors.forename: Yanxin
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jinglai
authors.initials: J
authors.lastname: Zhang
mesh_terms: D000042:Absorption; D004583:Electrons; D008958:Models, Molecular; D008968:Molecular Conformation; D015125:Oxyquinoline / Q000737:chemistry*; D011804:Quinolines / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet
chemical_list: C586937:8-hydroxylquinoline; D011804:Quinolines; D015125:Oxyquinoline
keywords: 8-Hydroxylquinoline; B3LYP; Electronic spectra; M06; Red shift