聚4-乙烯基吡啶与Cu(Ⅱ)离子配合过程及配合物的结构

Coordination Process and Complex Structure between Poly(4-vinylpyridine) and Cu(Ⅱ) Ion

采用粘度法确定了聚4-乙烯基吡啶(P4VP)在乙醇/水混合溶剂中的临界交迭浓度c*,分别在稀溶液与亚浓溶液浓度范围内,采用光谱法与电导滴定法研究了P4VP与Cu(Ⅱ)离子的配合过程及配合物的结构,通过红外光谱(FTIR)对配合物的化学结构进行了表征,并用差示扫描量热法(DSC)测定了配合物的热性能．结果表明,对于相对分子质量为1.06×105的P4VP,其c*为15 mmol·L-1(按P4VP中的链节量计算)．在稀溶液中P4VP与Cu(Ⅱ)离子形成可溶性的分子内配合物,表观配位数为9-10;在亚浓溶液中,P4VP与Cu(Ⅱ)离子发生分子间配合作用,由于配位交联,形成不溶性的配合物P4VP-Cu(Ⅱ),配位数为3．P4VP与Cu(Ⅱ)离子形成配合物后,玻璃化温度明显提高．

The critical overlap concentration c^＊ ofpoly （4-vinylpyridine） （P4VP） in a mixed solvent of ethanol and water （V/V=1/1） was determined with viscometry. Afterward, the coordination process and complex structure between P4VP and Cu^2＋ ions were studied in dilute solution range and semi-dilute solution range with visible spectral method and coordination-conductometric titration method, respectively. The chemical structure of the complex was characterized by FTIR spectra, and the thermal property was measured with differential scanning calorimetry （DSC）. The experiment results show that the critical overlap concentration c^＊ for P4VP with Mr=1.06×10^5 is 15 mmol· L^-1. In dilute solution, the intramolecular coordination of the macromolecular chains of P4VP with Cu^2＋ performs, and a blue soluble complex forms. It was found that the intramolecular complex needed at least nine or ten ligand units per cupric ion owing to the rigidity of polymer chains and the steric hindrance of bulky pyridine rings. Over the critical overlap concentration c^＊, namely in semi-dilute solution, the intermolecular coordination of the macromolecular chains of P4VP with Cu^2＋ takes place, an insoluble complex P4VP-Cu（Ⅱ） forms due to coordination crosslinking, and the coordination number of the complex is three. The glass transition temperature （Tg） of the complex P4VP-Cu（Ⅱ） is higher than that of P4VP.