title: Study on the interaction between nitroxide free radical and conjugated polyelectrolytes by fluorimetry.
abstract: In this work, we studied the fluorescence quenching of the anionic conjugated polyelectrolyte PPE-SO(3) by the paramagnetic species 2,2,6,6-tetramethylpiperidine-N-oxide free radical (TEMPO) in aqueous solution. At low quencher concentration the Stern-Volmer constant is 94 mol/L; as the quencher concentration increases the Stern-Volmer plots become superlinear. Ascorbic acid is used to reduce TEMPO to the corresponding hydroxylamine and the PPE-SO(3) fluorescence is fully recovered. Under a large excess of ascorbic acid over TEMPO, the rise of fluorescence followed pseudo-first-order kinetics. The second-order rate constant calculated from this time course is 0.7 mol/L/s.
authors.affiliation: Department of Analytical Chemistry, College of Chemistry, Jilin University, Changchun 130012, People's Republic of China.
authors.forename: Wenchao
authors.initials: W
authors.lastname: Dou
authors.forename: Xingguang
authors.initials: X
authors.lastname: Su
mesh_terms: D001205:Ascorbic Acid / Q000737:chemistry; D003497:Cyclic N-Oxides / Q000737:chemistry; D004573:Electrolytes / Q000737:chemistry; D005470:Fluorometry; D005609:Free Radicals / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D009589:Nitrogen Oxides / Q000737:chemistry*
chemical_list: D003497:Cyclic N-Oxides; D004573:Electrolytes; D005609:Free Radicals; D009589:Nitrogen Oxides; C039900:nitroxyl; D001205:Ascorbic Acid; C003959:TEMPO