title: Exploring molecular structures, orbital interactions, intramolecular proton-transfer reaction kinetics, electronic transitions and complexation of 3-hydroxycoumarin species using DFT methods.
abstract: Optimal structures and electronic properties of various species of 3-hydroxycoumarin (3-HCou) have been explored using density functional theory (DFT) methods under polarizable continuum model (PCM) of solvation. Electron transfer from pyrone to benzene moieties is enhanced upon deprotonation. Anionic and radical species have similar orbital-interaction characteristics but the charges in the former are distributed more uniformly. The rate of intramolecular proton transfer for the neutral species increases many folds upon excitation. The HOMO-LUMO transition with π→π* character mainly accounts for the UV absorption of most 3-HCou species in solution. The wavelengths of maximal absorption predicted using TD-DFT method are in agreement with the previous experiment. For the charged species, calculations with the range-corrected functional yield better agreement with the previous experiment. Anionic 3-HCou species shows high degrees of complexation with chromium(III) and copper(II) compared with oxovanadium(IV) and zinc(II). Either oxovanadium(IV) or zinc(II) prefers forming two isomeric complexes with comparable degrees of formation.
authors.affiliation: Department of Chemistry, Faculty of Science, Burapha University, Chonburi 20131, Thailand.
authors.forename: Nuttawisit
authors.initials: N
authors.lastname: Yasarawan
authors.affiliation: Department of Chemistry, Faculty of Science, Burapha University, Chonburi 20131, Thailand. Electronic address: khajadpa@buu.ac.th.
authors.forename: Khajadpai
authors.initials: K
authors.lastname: Thipyapong
authors.affiliation: Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Vithaya
authors.initials: V
authors.lastname: Ruangpornvisuti
mesh_terms: D003198:Computer Simulation; D003374:Coumarins / Q000737:chemistry*; D006860:Hydrogen Bonding; D007700:Kinetics; D008958:Models, Molecular; D008968:Molecular Conformation; D010084:Oxidation-Reduction; D011789:Quantum Theory; D013816:Thermodynamics
chemical_list: D003374:Coumarins
keywords: Complexation; Hydroxycoumarin; PCM; Proton transfer; Range-corrected functional; TD-DFT