SF₅-Terminated Fluorinated Schiff Base Liquid Crystals

Abstract

Novel liquid crystals based on fluorinated carbon chains and terminated with SF 5 groups are presented for the first time. Attachment of an SF 5 group separated from a benzylidine group by a fluorinated spacer leads to monotropic nematic and smectic phases, while an enantiotropic nematic phase is observed in mixtures. The phase sequence of these new compounds is comparable to hydrocarbon analogues of nO.m (n-alkoxym-alkylbenzylidine) series. Despite a long alkoxy chain, the nematic f smectic A transition is closer to second order, with M TCP predicted ≈ 0.995 values that are even higher than for the nCB (n-alkylcyanobiphenyls) series. Single crystal and quantum computational studies suggest that electrostatic interactions play a major role in governing the value of M TCP . Molecular packing in the crystal structure exhibits monoclinic P2 1 /a symmetry. A flexible synthetic strategy that allows the synthesis of another homologous series with a bend in the molecular structure is also presented. The bent core structure of 10O.2 SF 5 investigated shows a monotropic, tilted smectic phase for the higher C 10 alkoxy chain. The compounds in this series reveal a high degree of undercooling (well above 50 °C), which is rationalized using finite size effects on nucleation.

Synthesis and characterization of fluorinated poly(azomethine ether)s from new core-fluorinated azomethine-containing monomers

“…phases. [24][25][26][27][28][29][30] It is interesting to note that such fluorinated liquid crystals have good stability, high voltage holding ratio, and specific resistance. Moreover, they are characterized with low threshold switching voltage (V th ) and small temperature coefficient of V th , and are, therefore, widely used now in LC displays.…”

Single crystal X-ray structural features of aromatic compounds having a pentafluorosulfuranyl (SF5) functional group

“…In particular, compounds containing the trifluoromethyl (CF3) group or sulfurpentafluoride (SF5) group have a key role in organofluorine chemistry due to their special properties such as low surface energy, hydrophobicity, high chemical resistance, high thermal stability and electronegativity. Compounds containing fluorinated groups have been also used as materials, polymers and organic superconductors [13][14][15][16][17][18]. Although SF5 bearing aromatic compounds have been getting huge attention, their crystal structures have been sparsely reported.…”

The influence of the excited-state substituent effect on the reduction potentials of Schiff bases

“…Schiff bases, also called as imines, are a class of compound containing C=N bond, which have various interesting properties and activities. Because of its wide range of applications in chemistry, biology, pharmaceutical areas, and materials, Schiff bases have drawn considerable attention of researchers from various fields for a long time.…”