A detailed study into the synthesis and characterization of achiral nonsymmetric dimeric bidentate ligands formed by combining salicylaldimine and cyanobiphenyl rodlike anisometric segments through a flexible spacer (varying in its length and parity) and their Cu(II) and Pd(II) complexes is reported. The spacer parity greatly influences the phase behavior of ligands; notably, the dimers with odd-parity spacer stabilize nematic, uniaxial smectic A and biaxial smetic A phases, while the even-members display nematic and / or smectic phase/s. Unlike ligands, both the metal complexes solely show nematic behavior. An odd–even effect, as noted for ligands, was observed for the nematic–isotropic transition temperatures and the associated entropy values of copper complexes, while such behavior was not found in the case of palladium complexes.
报道了通过柔性间隔基(长度和奇偶性不同)将
水杨醛亚胺和
氰基
联苯棒状不等轴片段结合形成的非手性非对称二聚二齿
配体及其 Cu(II) 和 Pd(II) 配合物的合成和表征的详细研究。间隔基奇偶性对
配体的相行为影响很大;值得注意的是,具有奇奇偶校验间隔基的二聚体稳定向列相、单轴近晶A相和双轴近晶A相,而偶数成员则显示向列相和/或近晶相。与
配体不同,这两种
金属配合物仅表现出向列行为。正如
配体所指出的,
铜络合物的向列-各向同性转变温度和相关熵值观察到奇偶效应,而在
钯络合物的情况下没有发现这种行为。