作者:Gemma C. Shearman、Gokhan Yahioglu、Johanna Kirstein、Lionel R. Milgrom、John M. Seddon
DOI:10.1039/b812724g
日期:——
A homologous series of three octakis-alkyl-substituted porphyrin (OAP) derivatives with alkyl chain lengths of C8, C10 and C12 has been synthesised. For each compound, both the free-base (i.e. two H-atoms) and the fourfold coordinated zinc complex were investigated, where the latter for each chain length was found to exhibit liquid-crystalline mesophase behaviour. At low temperatures all three metal coordinated compounds formed a solid S phase with a structure based on a square packing of columns with a stacking periodicity of approx. 4.5 Ã
. At increased temperatures the square packed solid S phases undergo phase transitions to liquid-crystalline columnar phases based on centred rectangular lattices of C2/m symmetry, with the ratio of the lattice parameters, a/b, ranging between 1 and 1.732. The a/b ratio exhibited two discontinuous jumps with increasing temperature prior to melting to the isotropic phase for Zn-OAP-C8, implying the existence of three columnar phases denoted Colr1, Colr2 and Colr3. For the longer chain length compounds, the number of mesophases formed was reduced, first to two for Zn-OAP-C10, then to one for Zn-OAP-C12.
合成了烷基链长为C8、C10和C12的三种八烷基取代卟啉(OAP)衍生物的同系物系列。对于每种化合物,都研究了游离碱(即两个氢原子)和四重配位锌配合物,其中发现每个链长的后者都表现出液晶中间相行为。在低温下,所有三种金属配位化合物形成固体S相,其结构基于柱的方形堆积,堆积周期约为。 4.5×。在升高的温度下,方形堆积固体 S 相基于 C2/m 对称性的中心矩形晶格进行相变,形成液晶柱状相,晶格参数之比 a/b 范围在 1 到 1.732 之间。 Zn-OAP-C8 在熔化到各向同性相之前,随着温度的升高,a/b 比值表现出两次不连续的跳跃,这意味着存在表示为 Colr1、Colr2 和 Colr3 的三个柱状相。对于较长链长的化合物,形成的中间相数量减少,Zn-OAP-C10 首先减少到两个,然后 Zn-OAP-C12 减少到一个。