Part I. Functionalization of porous silicon surfaces for bio-sensor applications. Part II. Synthesis, structure and olefin polymerization kinetics of half-sandwich titanium and zirconium aryloxide complexes
The first part of the dissertation describes the porous silicon functionalization studies for bio-sensor applications. Preliminary results towards the development of porous silicon-DNA chips are presented. A heterobifunctional linker is synthesized and attached to the hydride terminated porous silicon surface by thermal hydrosilylation. The subsequent coupling of DNA phosphoramidites is successfully achieved by using phosphoramidite chemistry. A method is developed for the reversible attachment of disulfide linkages on porous silicon surface which offers a promising route towards obtaining controlled binding and release of bio-molecules from porous silicon surfaces. The second part of the dissertation describes the synthesis, characterization and polymerization studies with new half-sandwich titanium and zirconium aryloxide complexes. A major synthetic hurdle for [Cp*Zr(OAr)R2] (Cp* = C 5Me5, OAr = aryloxide, R = alkyl) complexes has been overcome by using a modified methyl lithium reagent, namely, MeLi•LiBr. Detailed kinetics of 1-hexene polymerization is reported for the [Cp*Zr(OC6H(Ph) 4-2,3,5,6)Me2]/B(C6F5)3 (3) catalyst system. From experimental rate measurements and advanced kinetic modeling, the propagation and deactivation rate constants for polymerization of 1-hexene with 3 are calculated. Polymerization of 100 equiv of 1-hexene by 3 is studied at temperatures between 25°C and 55°C (10 mM [Zr]). The activation parameters are, E a = 29 (1) kJ mol-1. ΔH ‡ = 27 (1) kJ mol-1 and ΔS ‡ = -123 (8) J mol-1 K-1. Quantitative rate measurements with a large set of half-sandwich titanium aryloxide catalysts and molecular descriptors obtained from density functional theory afford a structure-functional correlation that predicts kp value reasonably well.
Omar, Purdue University.
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