Chemical thermal and spectral characterization of hydrogen bonded liquid crystals

Abstract

Liquid Crystals (LCs) are beautiful and mysterious; with its unique newlinebehaviour it attracts many scientists to work on this soft condensed matter. newlineLCs can act as two different state of matter at the same time, that is both as newlineisotropic liquid and the crystalline solid phase. LCs are also called as newlinemesophases and their application area is wide especially its optical properties newlineare utilized effectively. The liquid crystalline phases are originated from three newlinetypes of order such as; Orientational order, Positional order, and Bond newlineorientational order. Thermotropic and lyotropic liquid crystals are the two newlinemain classes of liquid crystals. The former liquid crystalline phase appears by newlinechanging temperature, and the latter phase appears by changing solution newlineconcentration of amphiphilic compounds. Apart from these two types, there is newlinea special case in which the liquid crystal domains are dispersed into the newlinepolymer matrix to form a Polymer Dispersed Liquid Crystals (PDLC). newlineSupramolecular Hydrogen Bonded Liquid Crystals (SHBLC) are formulated newlineand recognized by the combination of two chemical ingredients by the weak newlinehydrogen bonding, which are formed when they have a pair of atoms, newlinepreferably a proton donor and an electron acceptor that leads to newlinecomplementary weak hydrogen bonding.The main objectives of the present work are detailed below: newline(a) To design and synthesize four novel series of hetero dimer liquid newlinecrystals which exhibits mesogenic property via intermolecular hydrogen newlinebonding. (b) To chemically, thermally and optically characterize all four newlineseries of LC comprising of 28 complexes. (c) To correlate the chemical newlinestructure of the designed mesogens with its physical prop newline newline