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该文合成了3种希夫碱镍金属催化剂:NiL1〔乙二胺缩香草醛Ni(Ⅱ)〕、NiL2〔邻苯二胺缩3,5-二叔丁基水杨醛Ni(Ⅱ)〕、NiL3(1S,2S-二苯基乙二胺缩水杨醛Ni(Ⅱ)),并用1HNMR、X-ray单晶衍射等方法对新合成的催化剂NiL3进行了表征。以NiL1为催化剂通过单因素分析,选择合适的L-LA(左旋丙交酯)本体开环聚合条件,在该聚合条件下,对比不同配体结构特点的催化剂NiL1、NiL2、NiL3的催化聚合效果,结果表明,催化剂配体结构中引入供电子基团甲氧基有利于提高催化剂活性;配体结构中在金属活性中心周围增大位阻效应有利于得到相对分子质量(简称分子量,下同)分布较窄的聚合产物。
In this paper, three kinds of Schiff base nickel metal catalysts were synthesized: NiL1 [ethylene diamine vanillin Ni (Ⅱ)], NiL2 [o-phenylenediamine tris-butyl salicylaldehyde Ni (Ⅱ)] , NiL3 (1S, 2S-diphenylethylenediamine salicylaldehyde Ni (Ⅱ)) were synthesized and characterized by 1HNMR and X-ray single crystal diffraction. Using NiL1 as catalyst, the suitable L-LA (L-lactide) ring-opening polymerization conditions were selected by single factor analysis. Under the polymerization conditions, the catalytic polymerization effects of catalysts NiL1, NiL2 and NiL3 with different ligand structure were compared The results showed that the introduction of the electron-donating group methoxy group in the catalyst ligand structure was beneficial to the improvement of the catalytic activity. Increasing the steric hindrance effect around the active center of the metal in the ligand structure is favorable for obtaining the relative molecular mass (molecular weight, the same below) Narrow distribution of the polymerization product.