Discotic liquid crystals of transition metal complexes. Part 26: Supramolecular structures of longchainsubstituted octaphenyltetrapyrazinoporphyrazine derivatives
作者:Kazuchika Ohta、Satoru Azumane、Wataru Kawahara、Nagao Kobayashi、Iwao Yamamoto
DOI:10.1039/a905538j
日期:——
Ten novel columnar liquid crystals, [octakis(4-alkoxyphenyl)tetrapyrazinoporphyrazinato]metal(II) (abbreviated as (C
n
O)
8
–M; n = 10, 12; M = Cu, Ni) and [octakis(3,4-dialkoxyphenyl)tetrapyrazinoporphyrazinato]metal(II) (abbreviated as (C
n
O)
16
–M; n = 8, 10, 12; M = Cu, Ni), have been synthesized and characterized. It was found that the mesophase structures of (C
n
O)
8
–M are very sensitive to the central metal and closely related to the aggregate structures in the solution. The (C
n
O)
16
–M derivatives exhibit a D
hd
mesophase at lower temperatures and a D
rd
(C2/m) phase at higher temperatures. Thus, the mesophase with higher symmetry appears at lower temperatures for these (C
n
O)
16
–M derivatives. This is quite opposite to the general tendency for the higher symmetry mesophase to appear at higher temperatures. In order to further clarify the structures of both the mesophases and the aggregate in solutions, the electronic and magnetic circular dichromism (MCD) spectra were measured. The Q band of (C
n
O)
16
–M in n-hexane showed a wide Davidov splitting. It was proven that such a wide splitting of the Q band can be attributed to the formation of dimers. The dimerization was confirmed by vapor pressure osmometric (VPO) measurements in n-hexane solution. Furthermore, the spectrum of the thin film in the mesophase in the absence of solvent at room temperature was similar to that of then-hexane solution. From these electronic absorption spectra, MCD spectra, VPO measurements and temperature-dependent X-ray diffraction studies, it was clarified for (C
n
O)
16
–M that the dimer structure in n-hexane solution is closely related to those in the thermotropic mesophases.
十种新型柱状液晶,[八烷基(4-烷氧基苯基)四吡嗪卟嗪]金属(II)(缩写为 (C n O) 8 -M;n = 10,12;M = Cu、Ni)和[八(3,4-二烷氧基苯基)四吡嗪卟嗪]金属(II)(缩写为 (C n O) 16 -M;n = 8、10、12;M = Cu、Ni)的合成和表征。研究发现,(C n O) 8 -M的介相结构对中心金属非常敏感,并与溶液中的聚合体结构密切相关。(C n O) 16 -M 衍生物在较低温度下表现出 D hd 介相,在较高温度下表现出 D rd(C2/m)相。因此,这些 (C n O) 16 -M 衍生物在较低温度下会出现对称性较高的介相。这与较高对称性介相在较高温度下出现的一般趋势截然相反。为了进一步弄清介相和聚合体在溶液中的结构,我们测量了电子和磁性圆重铬(MCD)光谱。(C n O) 16 -M 在正己烷中的 Q 波段显示出很宽的戴维夫分裂。实验证明,Q 波段出现如此宽的分裂是因为形成了二聚体。在正己烷溶液中进行的蒸气压渗透压(VPO)测量证实了二聚体的形成。此外,在室温下无溶剂介相薄膜的光谱与当时正己烷溶液的光谱相似。通过这些电子吸收光谱、MCD 光谱、VPO 测量和温度相关的 X 射线衍射研究,可以明确 (C n O) 16 -M 在正己烷溶液中的二聚体结构与热致性介相中的二聚体结构密切相关。