title: Ligand sensitized luminescence of uranyl by benzoic acid in acetonitrile medium: a new luminescent uranyl benzoate specie.
abstract: Benzoic acid (BA) is shown to sensitize and enhance the luminescence of uranyl ion in acetonitrile medium. Luminescence spectra and especially UV-Vis spectroscopy studies reveal the formation of tri benzoate complex of uranyl i.e. [UO2(C6H5COO)3](-) which is highly luminescent. In particular, three sharp bands at 431, 443, 461nm of absorption spectra provides evidence for tri benzoate specie of uranyl in acetonitrile medium. The luminescence lifetime of uranyl in this complex is 68μs which is much more compared to the lifetime of uncomplexed uranyl (20μs) in acetonitrile medium. In contrary to aqueous medium where uranyl benzoate forms 1:1 and 1:2 species, spectroscopic data reveal formation of 1:3 complex in acetonitrile medium. Addition of water to acetonitrile results in decrease of luminescence intensity of this specie and the luminescence features implode at 20% (v/v) of water content. For the first time, to the best of our knowledge, the existence of [UO2(C6H5COO)3](-) specie in acetonitrile is reported. Mechanism of luminescence enhancement is discussed.
authors.affiliation: Materials Chemistry Division, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India.
authors.forename: Satendra
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Materials Chemistry Division, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India.
authors.forename: S
authors.initials: S
authors.lastname: Maji
authors.affiliation: Fuel Chemistry Division, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India.
authors.forename: M
authors.initials: M
authors.lastname: Joseph
authors.affiliation: Materials Chemistry Division, Chemistry Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India. Electronic address: ksran@igcar.gov.in.
authors.forename: K
authors.initials: K
authors.lastname: Sankaran
mesh_terms: D000097:Acetonitriles / Q000737:chemistry*; D001565:Benzoates / Q000737:chemistry*; D019817:Benzoic Acid / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D049449:Luminescence; D012997:Solvents / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D017974:Uranium Compounds / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D000097:Acetonitriles; D001565:Benzoates; D008024:Ligands; D012997:Solvents; D017974:Uranium Compounds; D014867:Water; D019817:Benzoic Acid; C032159:acetonitrile
keywords: Acetonitrile; Benzoic acid; Luminescence; Sensitization; Uranyl