Preparation Of Optically Active Poly (Meth) Acrylamide Derivatives And Study Of Molecular Recognition Properties

Many polymethacrylamides bearing optically active side chains have been used as chiral stationary phase (CSPs) for high-performance liquid chromatography (HPLC) to separate chiral drug, at the same time, the amide groups is very good hydrogen bond donor, so it can be used as receptor molecules in anion recognition. In this work, two kinds of optically actively methacrylamide derivatives were synthesized, respectively. Then their chiral recognition abilities as chiral stationary phases (CSPs) for HPLC and anion recognition abilities were investigated.The novel optically active methacrylamide derivatives, (S)-(N-phenyl ethyl)-methyl acrylamide ((S)-MPMA), 3-Ethoxy silylpropyl methacrylamide (3-T-PMA), N-(S)-(N-(R)-(1-phenyl ethyl amide)-pyrrolidine)-acrylamide ((R,S)-APEPCA) and 1-acryloy-(S)-yrrolidine-2-carboxylic acid ((S)-APCA) were separately synthesized by Shorter-Bowman or amidation reaction in this study.In this study, optically active copolymers of N-[(S)-(+)-a-methylbenzyl] methacrylamide((S)-MPMA) and a amount of N-(3-(triethoxysilyl)propyl) methacrylamide (3-T-PMA) were successfully immobilized onto silica gel via the intermolecular polycondensation of the triethoxysilyl groups on the polymer. The chiral recognition ability of different immobilized-type CSPs and different eluents was evaluated by HPLC. The increase of 3-T-PMA in CSPs or decrease of isopropanol in eluents show a better chiral recognition ability. The CSP have the best chiral recognition ability for racemate 3 (2,2'-dihydroxy-6,6'-binaphthyl phenyl) and racemate 6 (6,6'-dibromo-1,1'-bi-2-naphthol) when adding THF to the eluent. The resolution for racemate 3 was effectively improved after adding chloroform.However, more content of chloroform can not contribute to the improvement of recognition abilities for the racemates except racemate 3.The anion recognition ability of PMPMA and PAPEPCA were evaluated using the tetra-n-butylammonium (TBA) salts of a series of anions in THF. A new absorption peak appeared in UV-Vis upon the addition of anions such as F-,I- and OH-. The fluorescence emission of polymers were significantly weaken, The optically active of polymers and monomers were tested by the polarimeter and circular dichroism (CD). From the experimental results found that the polymers form secondary structure. From CD spspectra of polymers under different temperatures and different solvents, we found the Cotton effect were increase with temperature rise or the content of methanol decreased. The results indicated that the hydrogen bonds in the polymers played an important role in the formation of secondary structure. Changing external environment affects the optically active of polymers. The Cotton effects were decreased after adding F-, Br-, I- and OH-. It should be noted that the Cotton effect of PMPMA not only decreased but also shifted to long wavelength by the addition of Br-. The 1H NMR titrations of polymers revealed that the changes of UV-Vis, CD and fluorescence emission were considered to be the direct consequence of the hydrogen-bonding complex formation between the amide group and the anions.