title: Absorption spectroscopic investigations involving 4f-4f transitions to explore the kinetics of complexation of Zn(II) with Pr(III)-glutathione complex.
abstract: The kinetics of complexation of Zn(II) with Pr2(GSH)2.(H2O)4 1 (GSH-glutathione) to form Pr2(GSH)2Zn(H2O)6 complex 2 has been investigated at 30 degrees C by following the changes in the intensity (absorbance, molar absorptivity) and intensity (oscillator strength P and Judd-Ofelt-T(lambda) intensity) parameters in equimolar DMF-Water. In order to support kinetics data, the complex 1 and 2 have been synthesized and characterized by elemental analysis, IR and 1H NMR spectral analysis. Molecular weights of 1 and 2 determined by ebullioscopic and cryoscopic methods and preliminary molecular modeling experiments have helped in proposing most probable structures for 1 and 2. Kinetics showed first order dependence, in terms of concentration of Zn(II) and complex 1, on the rate of formation of complex 2. Generally, hypersensitive transitions (the transitions obeying /DeltaJ/ selection rules) were used in spectra-structure correlation studies. We have used the four 4f-4f transitions of Pr(III), which do not obey selection rules, yet are substantially sensitive to coordination changes, for kinetic study. The rate constants evaluated from individual 4f-4f bands are quite close hence supporting our observations on ligand mediated pseudohypersensitivity.
authors.affiliation: Central Salt and Marine Chemicals Research Institute, Bhavnagar 364 002, Gujarat, India. salt@csir.res.in
authors.forename: Minaz A
authors.initials: MA
authors.lastname: Gagnani
authors.forename: Ram S
authors.initials: RS
authors.lastname: Shukla
authors.forename: Sudhindra N
authors.initials: SN
authors.lastname: Misra
mesh_terms: D005978:Glutathione / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D011221:Praseodymium / Q000737:chemistry / Q000378:metabolism*; D013055:Spectrophotometry, Infrared; D015032:Zinc / Q000737:chemistry / Q000378:metabolism*
chemical_list: D005978:Glutathione; D015032:Zinc; D011221:Praseodymium