title: Solvatochromaticity and pH dependence of the electronic absorption spectra of some purines and pyrimidines and their metal complexes.
abstract: The solvatochromic responses of uric acid (Ua), 6-amino-2-thiouracil (ATU) and a series of their complexes dissolved in ten solvents of different polarity have been measured. The solvent-dependent UV/Vis spectroscopic absorption maxima, λ(max), are assigned to the corresponding electronic transitions and analyzed using SPSS program, regression analysis and Kamlet and Taft methods. The observed solvatochromism is discussed using various solute-solvent interaction mechanisms. The electronic absorption spectra of ATU were investigated in aqueous buffer solutions of varying pH and utilized for the determination of dissociation constants. The ranges of pH, where individual ionic species are predominant have been determined.
authors.affiliation: Chemistry Department, Faculty of Science, Alexandria University, Egypt.
authors.forename: Mamdouh S
authors.initials: MS
authors.lastname: Masoud
authors.forename: Medhat A
authors.initials: MA
authors.lastname: Shaker
authors.forename: Alaa E
authors.initials: AE
authors.lastname: Ali
authors.forename: Gehan S
authors.initials: GS
authors.lastname: Elasal
mesh_terms: D056831:Coordination Complexes / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D011687:Purines / Q000737:chemistry*; D011743:Pyrimidines / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013889:Thiouracil / Q000031:analogs & derivatives
chemical_list: D056831:Coordination Complexes; D011687:Purines; D011743:Pyrimidines; D013889:Thiouracil