Abstract
I study the stereoelectonic effect of silicon-containing b,g-enals and the novel controllable photoinduced DNA cleavingprocess by use of nitrones, organometallic complexes (i.e.,ruthenium and platinum metal complexes containing pyridine N-oxide), and organic nitrates and nitriles. The mechanism ofsilicon to direct photodecarbonylation was investigated.Photolysis of deuteriated trimethylsilyl-containing b,g-enals inan ethanolic solution containing potassium carbonate with UVlight produced deuteriated b,g-enals. Their kinetic isotopeeffect, relevant rate constants and the energy of the possibleconformation were well studied. Analysis the results indicatethat the silicon directed the C-CHO bond cleavages in Si-C-C-CHObackbone through deformylation and intramolecular deuteriumrecombination. The overall "carbonyl extrusion" processesinvolve a stepwise mechanism. The trimethylsilyl group trans tothe formyl group provided a greater stabilization effect throughhyperconjugation than the corresponding cis alignment for thedeformylation because of the possible antiperiplanar orientaion.Nitrones, ruthenium clusters complexes coordinated with1-hydoxybenzotriazole and 1-hydroxypyridine-2-thione, andorganoplatinum complexes containing 1-hydroxypyridine-2-thioneas well as phthalimide nitrates and nitrites were studied asphotoinduced DNA cleaving agents. These compounds wereirradiated with UV light to result in the single strand scissionof supercoiled DNA. The results of autoradiogram of thepolyacrylamide gels indicate they can cleave DNA at specificbase moiety. The mechanism and binding process of the DNAcleavage were also studied in this dessertation.