Discotic metallomesogens: mesophase crossover of columnar rectangular to hexagonal arrangements in bis(hydrazinato)nickel(II) complexes
作者:Chung K. Lai、Chun-hsien Tsai、Yung-shyen Pang
DOI:10.1039/a800657a
日期:——
Three series ofN-(3,4-dialkoxybenzylidene)-N′-(3′,4′,5′-trialkoxybenzoyl)hydrazine and their nickel(ii) complexes, bis[N-(3,4-dialkoxybenzylidene)-N′-(3′,4′,5′-trialkoxybenzoyl)hydrazinato]nickel(ii), were prepared and characterized. The mesomorphic properties of these disc-like compounds were also studied in terms of liquid crystallinity. The orange nickel(ii) complexes with ten soft alkoxy side chains exhibited columnar disordered mesophases, which were characterized based on DSC analysis and optical polarized microscopy. Nickel complexes with shorter side chains (n=5–8) displayed a monotropic columnar rectangular disordered (Colrd) phase; however, complexes with longer side chains showed monotropic (n=10) and enantiotropic (n=12, 14) columnar hexagonal disordered (Colhd) phases. Similar nickel complexes (n=14) with eight side chains exhibited a columnar hexagonal phase, whereas complexes (n=14) with six side chains formed crystalline phases. The structures of these columnar disordered phases were confirmed by X-ray powder diffraction. XRD data indicated that mesophase crossover from columnar rectangular (Colr) to hexagonal arrangements (Colh) was observed with increasing side chain lengths.
合成了三种系列的N-(3,4-二烷氧基亚苄基)-N′-(3′,4′,5′-三烷氧基苯甲酰)酰肼及其镍(II)配合物,[N-(3,4-二烷氧基亚苄基)-N′-(3′,4′,5′-三烷氧基苯甲酰)酰氨基]合镍(II),并对化合物进行了表征。我们还研究了这些类圆盘状化合物的液晶特性。具有十个柔软烷氧基侧链的橙色镍(II)配合物表现出柱状无序液晶相,这一特性通过DSC分析和光学偏振显微镜得到了表征。含有较短侧链(n=5–8)的镍配合物呈现出单变型柱状矩形无序(Colrd)相;然而,具有更长侧链的配合物呈现出单变型(n=10)和同变型(n=12, 14)柱状六方无序(Colhd)相。类似镍配合物(n=14)具有8个侧链时出现柱状六方相,而6个侧链时则形成晶态相。这些柱状无序相的结构通过X射线粉末衍射得到了确认。XRD数据显示,随着侧链长度的增加,液晶相从柱状矩形(Colr)转变为六方排列(Colh)。