Synthesis And Application Of Photoresponsive Molecularly Imprinted Catalyst Based On L-proline For Aldol Reaction

In recent years, stimuli-responsive catalytic materials have attracted more and more concern and gradually become a hot research topic in organic catalysis chemistry. Stimuli-responsive catalytic materials can not only promote/slow reaction process, but also can respond to change in external stimuli, thus realize the motivated control of catalytic reaction. Molecularly imprinted polymers (MIPs) combine the advantages of excellent anti-poor environmental conditions, long-durability, good stability, and specific recognition. In this thesis, two photoresponsive moleculary imprinted catalysts based on L-proline were designed and synthesized, these catalysts were used for photocontrolled aldol reaction. The detailed research contents are described as follows:1. In Chapter One, molecular imprinting technique (MIT) and stimuli-responsive materials (SPMs) were briefly introduced. The origin, development, and application of MIT and SPMs, and the current research progress of MIT in catalysis field were outlined. Secondly, the application of stimuli-responsive molecularly imprinted materials and the research status of photoresponsive catalytic materials in photoresponsive field were reviewed. Finally, the design of photoresponsive catalytic materials via MIT was raised.2. In Chapter Two, a functional azobenzene monomer 4-[(4-methacryloyloxy)phenylazo] benzenesulfonic acid (MAPASA) was prepared by diazotization coupling and esterification reactions using the sulfonic aniline, phenol, and methacrylic acid as the starting materials. Its chemical structure and photoresponsive performance were characterize via 1H NMR,13C NMR, and UV-Vis, respectively. A photoresponsive MIP was prepared with proline as template, MAPASA as functional monomer, and EGDMA or TRIM as the cross-linker. The influence of cross-linker and the molar ratio of template/functional monomer were discussed. Based on photoresponsive properties and the ability of uptake and release of L-proline, polymers with better properties were selected as catalysts for photocontrolled aldol reaction. achieve photoswitchable catalysis in Aldol reaction. The photocontrolled catalytic conditions including solvent, amount of MIP, adsorption concentration, reaction time, and reaction temperature were optimized. The scope and recyclibility of the molecularly imprinted catalyst were discussed. The molecularly imprinted catalysts were characterized via SEM, TG, FT-IR, and N2 adsorption desorption analysis.3. In Chapter Three, a functional azobenzene monomer 4-(pyrrole 2-carboxamido)-4’-methylacrylate Azobenzene PCMAAB with photoresponsive properties and catalytic activity was prepared by diazotization coupling, esterification reaction, reduction, amidation, and Boc protection using p-nitroaniline, phenol, methacrylic acid, proline and Boc acid anhydride as the starting materials. Its chemical structure, photoresponsive performance and catalytic activity were characterized via’H NMR, UV-Vis, and HPLC, respectively. A photoresponsive molecularly imprinted polymer (MIP) was prepared using the product of aldol reaction as the template, PCMAAB as the functional monomer, and EGDMA as the cross-linker. The influence of the molar ratio of cross-linker and functional monomer on the MIP polymer was discussed. Based on photoresponsive properties, MIP with better properties was selected as catalysts for photocontrolled aldol reaction, and the photocontrolled catalytic conditions were optimized. The recyclibility of the molecularly imprinted material was investigated. The molecularly imprinted catalysts were characterized via SEM, TG, FT-IR, and N2 adsorption desorption analysis.4. In the last Chapter, the main results and conclusions were summarized, and some recommendations for future work are given.