Halogen-bonded liquid-crystalline complexes formed from 4-alkoxyphenylpyridines with iodine and with interhalogens

Abstract

Strongly halogen-bonded complexes are formed between 4-alkoxyphenyl-4-pyridines and iodine as well as the interhalogen compounds ICl and IBr, and examples of each are characterised by single crystal X-ray crystallography. On...

Halogen‐Bonded Liquid Crystals

“…Halogens and interhalogens tend to form rather strong halogen bonds [55] and there are reports of liquid-crystalline complexes formed with iodine, bromine and some interhalogens (Figure 18). [10,56,57] Some of the complexes were characterised crystallographically and, for example, in a complex between an alkoxyphenylpyridine and ICl, a N•••I distance of 2.276(2) Å was found, which represents only 64 % of the sum of the van der Waals' radii. In general, these complexes showed mesophases to quite elevated temperatures, maybe ca.…”

“…[10] In contrast, in reporting the behaviour of the azopyridines, Chen et al not only prepared complexes of bromine but showed them to have liquid crystal properties, with textures given in the manuscript. [57] There are some aspects of the thermal behaviour that are not explained and the characterisation of the complexes is perhaps incomplete, but nonetheless, it is believed that these latter complexes are the only examples of liquid crystals with a halogen bond to bromine. Second was the observation that the longer-chain homologues of the stilbazole•••I 2 complexes showed a SmC phase.…”