Structures, Spectral, Thermal and Radiochemical Studies of Some Transition Metal Complexes of Biologically Active Nucleic Acid Constituents

Abstract

The reaction of 99mTc pertechnetate with 5, 5´-diethyl barbituric acid, adenine, d-glucose and thiobarbituric acid at different temperatures was studied. The solvent effect on the electronic absorption spectra of the reactions was recorded. The reaction mixtures have been analyzed at different times using TLC and a radiodetctor to show the peaks at the plates. The solvatochromism for the reaction of 99mTc with d-glucose was mainly affected by solute permanent dipole-solvent permanent dipole interaction, the dipolar interaction for the reaction of 99mTc with of 5, 5´-diethyl barbituric acid and for the reaction of 99mTc with adenine and thiobarbituric was solute-solvent hydrogen bonding. D-glucose , thibarbituric acid, adeniene and 5, 5´-diethyl barbituric acid complexes with Mo(VI), Cr(III) and Mn(II) have been prepared and characterized by elemental analysis, IR, UV–Vis spectra, and thermal analyses. The data suggest octahedral geometries for all the prepared complexes except for d-glucose-manganese complex (Mn 3(L)2 (OH)(H2O)6Cl). The thermal behavior of the complexes has been studied by applying TG, DTA, and DSC techniques, and the thermodynamic parameters and mechanisms of the decompositions were evaluated and discussed. The influences of the structural properties of the chelating agent and the type of the metal on the thermal behavior of the complexes, the order (n) and the heat of activation (E) of the various decomposition stages were determined from the TG and DTA. The reaction of some the prepared complexes with 18F- in different media was studied. Characterization of the 18F- complexes and the determination of the extent of radiolabeling was done by thin layer chromatography using (95:5) acietonitrile to water solution as a solvent Different techniques (ozonolysis, UV, distillation and resin) were used to minimize the concentration of both organic inorganic impurities of waste 18O-enriched water and the results were compared. Ozonolysis and distillation gave the best results in minimizing both organic inorganic impurities, respectively.