Synthesis, Characterization and Study of Mesomorphic Behavior of New Bent and Liner Core Compounds Containing Heterocyclic

Alaa K Shanshal,Nisreen H Karam

doi:10.30526/30.3.1615

Abstract

We described herein the synthesized and characterized of new bent and liner core compounds containing thiazolidin-4-one ring[XI-XIII] and [XIV-XVI] respectively. These compounds synthesized by sequence reactions starting from reaction resorcinol or hydroquinone with chloracetyl chloride to yield compounds [I] and [II] ,then the later compounds reactant with 4-hydroxybenzylaldehyde to product dialdehyde compounds [III] and [IV] .The Schiff bases compounds[V-VII] and [VIII-X] synthesized from reaction the compound [III] or [IV] with different aromatic amines, while the bent and liner core mesogens containing thiazolidin-4-one ring [XI-XIII] and [XIV-XVI] synthesized from reaction Schiff bases compounds[V-VII] or [VIII-X] with thioglycolic acid. In addition estrfecation of cinnamic acid with methanol to yield ester compound[XVII]which was converted to their acid hydrazid[XVIII] and the acid hydrazid reacted with glysine in phosphorous oxychloride to yield (5-styryl-1,3,4-oxadiazol-2-yl) methanamine [XIX]. Then reactant the1,3,4-oxadiazol compound[XIX] with dialdehyde compound [III] or [IV] to product new Schiff bases compounds [XX] and [XXI] , afterword added thioglycolic acid to give new thiazolidin-4-one derivatives [XXII] and [XXIII], respectively. The synthesized compounds were characterized by melting points , FTIR ,1HNMR and mass spectroscopy (of some of them).The liquid crystalline properties were studied by hot stage polarized optical microscopy (POM) and differential scanning calorimetry(DSC).All the Schiff bases compounds [V-X] showed liquid crystals phases while thiazolidin-4-one derivatives[XI-XIII],[XIV-XVI]and [XXIII] didn’t show any liquid crystals properties except the compound [XXII] showed enantiotropic nematic phase.

Highlights

In recent years, there has been interest study of liquid crystals resulting in the discovery of many applications in modern technologies, in display devices due to their unusual optical and electrical properties
Many workers synthesized bent or liner core liquid crystals compounds containing1,3disubstitutedphenylene or 1,4-disubstitutedphenylene from resorcinol or hydroquinone, respectively, as Ciobanu et al.[4] synthesized and investigated liquid crystalline behavior of symmetrical non liner liquid crystal containing 1,3- disubstituted benzene ring as a central core consisting of different linkage groups beside to terminal alkyloxy chain containing 6 to 10 carbon atoms(1).All compounds appeared enantiotropic mesophases
Huzum et al.[5]synthesized and studied mesomorphic behavior of two new series of bent core liquid crystalline compounds based on a 1,3-dihydroxybezene core and containing a cholesteryl 6-oxyhexanoate wing

Summary

Introduction

There has been interest study of liquid crystals resulting in the discovery of many applications in modern technologies, in display devices due to their unusual optical and electrical properties. Many workers synthesized bent or liner core liquid crystals compounds containing1,3disubstitutedphenylene or 1,4-disubstitutedphenylene from resorcinol or hydroquinone, respectively, as Ciobanu et al.[4] synthesized and investigated liquid crystalline behavior of symmetrical non liner liquid crystal containing 1,3- disubstituted benzene ring as a central core consisting of different linkage groups beside to terminal alkyloxy chain containing 6 to 10 carbon atoms(1).All compounds appeared enantiotropic mesophases (nematic and smectic phases). Huzum et al.[5]synthesized and studied mesomorphic behavior of two new series of bent core liquid crystalline compounds based on a 1,3-dihydroxybezene core and containing a cholesteryl 6-oxyhexanoate wing. One the other hand ,synthesized liner core liquid crystals compounds containing 1,4disubstitutedphenylene from hydroquinone as, synthesized three aromatic rigid mesogenicdiols(3) based on hydroquinone and 4-hydroxy benzoic acid as starting materials[8]. Massspectrum was determined by scan110(1.257min):direct prob-013777.d,at Central lab ,Tehran University.uncorrected melting points were determined by using Hot-Stage, Gallen Kamp melting point apparatus.The transition temperatures and textures of the mesophases were determined using polarized opticalmicroscope model Leica DM2500 Mand DSC measurements were conducted with STAPT-1000LINSIS

HC N C

Results and discussion

C OH2 CH2NH2