Part 1. Imidazolium-based ionic liquids as modulators of the critical micelle concentration of sodium dodecyl sulfate. Part 2. Synthesis and antioxidant studies of carnosine related dipeptides.

摘要

This dissertation is divided into two parts. The first part of the research involves investigation of critical micelle concentration (CMC) of sodium dodecyl sulfate (SDS), an anionic surfactant, in aqueous solutions of a variety of room temperature ionic liquids (RTILs): 1,3-Dimethylimidazolium iodide (Me 2IM-1), 1-butyl-3-methylimidazolium chloride (BMIM-Cl), 1-hexyl-3-methylimidazolium chloride (HxMIM-Cl), 1-octyl-3-methylimidazolium chloride (OMIM-Cl,), 1-octyl-3-methylimidazolium tetrafluoroborate (OMIM-BF4,), 1-benzyl-3-methylimidazolium chloride (C6H5CH2)MIM-Cl, and 1-methyl-3-(pentafluorophenyl)methylimidazolium chloride (C6F5CH2)MIM-Cl. The CMC of SDS is shown to correlate with the nature of the alkyl groups in the RTILs; SDS showed appreciably higher CMCs in presence of Me2IM-I and BMIM-Cl, whereas in the presence of ionic liquids HxMIM-Cl, OMIM-Cl and OMIM-BF4 much smaller CMCs were observed. The range of CMC values observed for these ionic liquids varied by a significant factor of 90. The nature of the gigenions, Cl- or BF4-, has no noticeable effect on the observed CMC values. Ionic liquid with fluorinated side chain, (C6F5CH2)MIM-Cl, exhibited dramatically lower CMC value as compared to those of the corresponding analogue (C 6H5CH2)MIM-Cl by a factor of 450.;The second part of the research involves synthesis and UV-vis spectrophotometric determination of Fenton reaction-mediated oxidative damage of carnosine and related antioxidants. Carnosine and related compounds act as effective neuroprotectors through their antioxidant and antiglycating properties. A convenient UV-vis assay was developed for the determination of relative antioxidant properties of the latter compounds. The UV-vis antioxidant-assay was performed using 3,3'-diaminobenzidine (DAB) as a readily oxidizable chromogen, and Cu +/H2O2 as the Fenton reagent, in Tris-HCl buffer. Novel analogues of carnosine were also synthesized and their antioxidant properties assayed using this technique. UV-vis method serves as a convenient and efficient method for estimating the relative antioxidant characteristics of carnosine and related compounds.