光学活性N-邻噁唑啉苯基甲基丙烯酰胺聚合物的合成及其手性光学性质  

SYNTHESIS AND CHIROPTICAL PROPERTY OF N-(o-OXAZOLINEPHENYL) METHACRYLAMIDE BASED OPTICACLLY ACTIVE POLYMERS

作　　者：刘光烜[1] 路伟[1] 江黎明[1] 孙维林[1] 沈之荃[1] 王玉康[1] 

机构地区：[1]浙江大学高分子科学与工程系高分子合成与功能构造教育部重点实验室,杭州310027

出　　处：《高分子学报》2009年第8期775-780,共6页Acta Polymerica Sinica

基　　金：国家自然科学基金(基金号20274036;20434020)资助项目

摘　　要：在三氟甲磺酸稀土盐(Ln(OTf)3,Ln=La,Nd,Sm,Y)的存在下,光学纯N-邻唑啉苯基甲基丙烯酰胺((S)-MeOPMAM)经自由基聚合反应得到相应的光学活性聚合物.考察了稀土盐种类、用量及溶剂性质等因素对聚合反应立体化学的影响.研究发现,以Y(OTf)3为调节剂、正丁醇为溶剂的体系能在一定程度上提高聚合反应的全同立体定向性.聚合物的手性光学性质明显依赖于立构规整度,随全同含量增大,聚合物的比旋光度和π-π*电子跃迁区域的Cotton效应强度呈下降趋势.利用1H-NMR技术研究了上述聚合物与1,1′-联-2-萘酚(BINOL)的对映选择性相互作用,结果表明,全同三元组含量较高的聚合物不仅使酚羟基质子峰向低场位移,而且导致信号分裂.Enantiopure methacrylamide derivative, N- [ o- （4-methyl-4,5-dihydro-1,3-oxazol-2-yl） phenyl] methacrylamide （（S）-MeOPMAM） was synthesized and radically polymerized in the presence of rare earth metal trifluoromethanesulfonates （Ln（OTf）3, Ln = La, Nd, Sm, and Y） to yield corresponding optically active polymers. Among these Lewis acids, Y（OTf）3 was found to be most effective for increasing the isotactic specificity during the radical polymerizations when using n-butanol as a solvent. The effect of the Lewis acids was significantly influenced by the ratio of Ln（OTf）3 to monomer and the nature of solvents. The tacticity of polymers was estimated by ^13 C-NMR spectroscopy on the basis of the peak splitting of the quaternary carbon of the main chain （ δ= = 46.5 - 48.5）. Theconventional polymerization without Y（OTf）3 produced syndiotactic-rich polymer with rr = 67%, while the polymer with a relatively high isotacticity （mm = 47% ） was obtained in the case of an equimolar amount of Y（OTf）3 to the monomer. Also, the addition of the rare-earth salt increased both the polymer yield and molecular weights. The relationship between the stereoregularity and the chiroptical property as well as the ehiral recognition was then examined for the resulting polymers with various taeticities by spectroscopic techniques such as circular dichroism （CD） and NMR. The syndiotactic-rich polymer showed a specific rotation of ＋ 118.6°; however, the absolute value of [ α]D^25 decreased with an increase in the isotactie triad content and a negative value （ - 2.1°） was observed for the polymer having mm= 47 %. Correspondingly, the CD intensities at 240 nm and 220 nm were depressed evidently. On the other hand, ^1H-NMR measurements of the mixture of poly [ （ S ）-MeOPMAM ] s and racemic 1, 1′-bi-2- naphthol （BINOL） were conducted in chloroform-d. The characteristic hydroxyl proton signal of BINOL was splitinto two peaks ascribed respectively to the levo- and dextro-isomer; further

关 键 词：自由基聚合 稀土盐 立构规整性 光学活性聚合物 手性识别 

分 类 号：O633.5[理学—高分子化学]