closo-B 10H 10] 2- anion: Investigation of liquid crystalline polymorphism in an homologous series of 1,10-bis(4-alkoxypyridinium) zwitterions]]>

摘要

A series of pyridinium bis-zwitterions [closo-B10H8-1,10-2 (4-ROC5H4N)] (1[n]) was obtained in 55–60% yield by reacting [closo-B10H8-1,10-2(IPh)] (3) with 4-alkoxypyridines and the resulting derivatives were analyzed for their liquid crystalline properties. Optical, thermal and XRD analyses revealed the formation of a nematic and rare lamellar phases, LamCr, driven by dipolar interactions. Upon elongation of the terminal alkoxy chain, the nematic phase is gradually replaced by the lamellar polymorphism. The solid-state structures of1[8],1[12]and1[16]were established by single crystal XRD:1[8]P21/c, Z?=?4,a?=?12.6009 (2) ?,b?=?20.7889 (2) ?,c?=?12.61150 (10) ?, β?=?103.9910 (10)°;1[12]P-1, Z?=?2,a?=?9.6262 (2) ?,b?=?12.0464 (2) ?,c?=?17.9226 (3) ?, α?=?80.5940 (10)°, β?=?83.0700 (10)°, γ?=?74.9860 (10)°;1[16]P-1, Z?=?2,a?=?9.6827 (3) ?,b?=?11.6711 (5) ?,c?=?22.8486 (7) ?, α?=?77.416 (3)°, β?=?86.925 (2)°, γ?=?66.202 (4)°.