Schiff Base liquid Crystals with Terminal Alkoxy Group Synthesis and Thermotropic Properties

Abstract

A new homologous series of Schiff base esters comprising a terminal alkoxy substituent N-{(nalkoxy-4``-bezoyloxy)-4`-benzylidene}-4-butyl aniline was studied. The alkyloxy substituent contributes to the molecular polarizability, thus, affecting intermolecular interactions, hence, resulting in nematic polymorphism. The mesomorphic properties were studied using polarizing optical microscope (POM). The lower members, n-methoxy and n-ethoxy derivatives were nonmesogens, enantiotropic nematogenic phase was observed on further lengthening of the alkyl chain from C3 to C6 and smectogenic phase was observed for compounds C7 and C8. FT-IR, 1 HNMR, 13 CNMR, EI-MS and elemental analysis were employed to elucidate the molecular structure of the title compounds whereas the liquid crystal properties were determined by POM analysis. The mesomorphic behaviors of the homologous compounds are rationalized based on the varying lengths of the alky chain.

2-Pyridinyl-Terminated Iminobenzoate: Type and Orientation of Mesogenic Core Effect, Geometrical DFT Investigation

“…The rings of the aromatic part are connected by linkage groups such as a Schiff base (-CH=N-). Therefore, it provides a stepped core structure and preserves the molecular linearity and develops high stability for the compound that enables mesophase formation [8,9]. Compounds containing Schiff bases have many applications; they act as systems with high thermal stability, corrosion inhibitors, and have some biological activity.…”

“…The mesophase becomes more stable when the mutual conjugation increases between the ester carbonyl and the substituent [10]. Several studies have used LC compounds containing a Schiff base ester mesogenic core because of their remarkable properties and wide temperature range [8]. Schiff base ester LCs containing two or three aromatic rings were noticed to have interesting optical behavior.…”

“…Moreover, LCs containing only one mesogenic core differ in behavior from other LCs having two or more mesogenic cores [13]. Furthermore, as the terminal substituent length increases, the molecules tend to arrange in a parallel orientation [8]. Moreover, to create new thermotropic LCs having phase transitions, it is important to select a proper mesogenic moiety, terminal groups, and flexible wings.…”