title: A physiochemical study of azo dyes: DFT based ESIPT process.
abstract: Azo linked dye derivatives were synthesized and characterized by NMR, mass and elemental analysis. An excited state intramolecular proton transfer (ESIPT) in hydroxy Schiff base has been analyzed, and found that two distinct ground state isomers of I and II are responsible for the observed dual emission. DFT calculation on energy, dipole moment, charge distribution of the rotamers in the ground and excited states support the ESIPT process. PES calculation indicates that the energy barrier for the interconversion of two rotamers is too high in the excited state than the ground state. By varying the addition of base concentration to hydroxy Schiff base, two isobestic points were found which confirm the equilibrium among the trans enol form, anion and the cis enol form. Fluorescence quenching with metal ions reveal that hydroxy Schiff base can be used as a new fluorescence sensor to detect the Cu(2+) ion.
authors: Department of Chemistry, Annamalai University, Annamalainagar, Tamilnadu, India. jtchalam2005@yahoo.co.in
authors: Jayaraman
authors: J
authors: Jayabharathi
authors: Venugopal
authors: V
authors: Thanikachalam
authors: Marimuthu Venkatesh
authors: MV
authors: Perumal
authors: Natesan
authors: N
authors: Srinivasan
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D004396:Coloring Agents / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D011789:Quantum Theory; D012545:Schiff Bases / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
chemical_list: D001391:Azo Compounds; D004396:Coloring Agents; D012545:Schiff Bases