A systematic investigation of reactions that form silicon -carbon bonds between organic molecules and porous silicon surfaces
Abstract
Reactions are discussed which are effective in partially transforming the hydride terminated surface of porous silicon samples into organic functionalized materials. Activation of the porous silicon surface toward unsaturated bonds leads to silicon-carbon bond formation, either by hydrosilylation or by the in situ generation of carbanion nucleophiles. By systematic exploration of reactivity patterns, the mechanisms for the surface reactions are evaluated, and the means for optimization of the functionalization process may become apparent. Lewis acid mediated hydrosilylations use the organic phase soluble catalyst EtAlCl2 to hydrosilylate alkenes and alkynes. Electrografting reactions on porous silicon use a nonaqueous electrolyte solution of an alkyne and an applied current to form silicon-carbon bonds; two different surface terminations are possible using the same alkyne solution; anodic current gives alkyl surfaces while cathodic currents give alkynes directly bound to porous silicon surfaces. Hydrosilylation reactions on photoluminescent porous silicon can be driven directly by exposure to white light. There is no solution or surface precedent for this reaction, for which an exciton-mediated nucleophilic attack mechanism is proposed. Another hydrosilylation reaction mediated by carbocations is described in a cursory fashion.
Degree
Ph.D.
Advisors
Buriak, Purdue University.
Subject Area
Chemistry|Organic chemistry
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