摘要：

The research presented and discussed within this dissertation involves the development of multifunctional mesoporous silica nanoparticles (MSN), and an investigation of performance of those MSN materials for heterogeneous catalysis.;A heterogeneous Lewis base MSN catalyst with an immobilized 4-dimethylaminopyridine functionality (DMAP-MSN) was synthesized, and have been demonstrated the catalytic activities of several nucleophilic reactions, such as acylation, silylation, and Baylis-Hillman reactions, and recyclable at least up to ten times. An unprecedented selectivity of Baylis-Hillman catalyzed by DMAP-MSN has also been observed, which could be attributed to size-discriminating effect induced by the 3-D cavity of regular mesoporous structure.;To take advantage of the double hydrogen bonding ability of urea and thiourea functionalities, I have synthesized a series of organically functionalized Lewis acid MSN catalysts with several urea or thoiourea functional groups. These heterogonous Lewis acid MSN materials have been demonstrated a capability to be serve as highly efficient catalysts for carbonyl activation of dienophiles in Diels-Alder reaction. I have discovered that the reactivity of the MSN catalysts is higher than those of the homogeneous analogs.;Multifunctionalization of mesoporous silica materials could be achieved with precise control the composition of each functionality as well as the particle morphologies. A variety of bifunctionalized MSN catalysts with one catalytic functional group, and another gatekeeper group to regulate diffusion of reactants. Fine-tuning local chemical mesoporous environment by different gatekeeper groups enabled to control the diffusion of substrates by hydrophilic/hydrophobic interactions, giving rise a selectivity in a competitive Henry reaction. The same strategy was also applied to yield several bifunctionalized MSN catalysts, comprised of acid and base functionalities inside the mesopores. These acid and base bifunctional MSNs exhibited a cooperative behavior by activation of nucleophile and electrophile.;A palladium (II) complex was also successfully immobilized on the mesoporous silica surface by a radical coupling reaction to yield the Pd(II) functionalized MSN(Pd-MSN) catalyst. The well-aligned mesoporous channels of Pd-MSN material allowed the encapsulation of conducting poly(p-phenylene ethynylene) (PPE) polymer by the Sonogashira coupling reaction. The resulting PPE-MSN nanocomposite exhibited interesting photophysical and electronic properties, which could lead to further developments of new optical and electronic nanodevices.

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