Polar Uç Gruplara Sahip Yeni Üç-Halkalı Kalkon-İmin Türevlerinin Sentezi, Yapısal ve Mesomorfik Karakterizasyonu

Abstract

Bu çalışmada, uç pozisyonlardan birinde n-dodesiloksi grubu, diğerinde ise siyano veya brom grubu bulunan üç-benzen-halkalı merkezi üniteden oluşan yeni kalkon-imin türevleri sentezlenmiştir. Elde edilen türevlerin kimyasal yapıları spektral analizlerle (1H-, 13C/APT-NMR ve FT-IR) aydınlatılmıştır. Türevlerin mesomorfik davranışları diferansiyel taramalı kalorimetri (DSC) ve polarize optik mikroskop (POM) ile gözlemlenmiştir. Siyano-uçlu kalkon-imin türevinin (3a) 19 ˚C termal sıcaklık aralığı ile karakterize edilen enansiyotropik SmA mesofazını ve ayrıca M mesofazını sergilerken, brom-uçlu kalkon-imin türevinin (3b) ise herhangi bir mesomorfik davranış göstermediği belirlenmiştir. Bu sonuç, polar uç grubunun türü ve doğasının moleküllerin sıvı kristal özelliklerini büyük ölçüde etkilediğini vurgulamaktadır.

Keywords

• Sıvı kristaller
• Kalkon-imin türevleri
• Mesomorfik davranış
• Çubuksu molekül

Synthesis, Structural and Mesomorphic Characterization of New Three-Ring Chalcone-Imine Derivatives with Polar End Groups

Abstract

In this study, new chalcone-imine derivatives composed of three-benzene-ring central unit containing n-dodecyloxy group at one end and cyano or bromo group at other end have been synthesized. Chemical structures of the obtained derivatives have been clarified by spectral analyses (1H-, 13C/APT-NMR and FT-IR). The mesomorphic behaviour and optical textures of the derivatives have been observed by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). It was determined that cyano-terminated chalcone-imine derivative (3a) exhibits enantiotropic SmA mesophase, characterized by thermal range of 19 ˚C and also a M mesophase, while bromo-terminated chalcone-imine derivative (3b) does not show any mesomorphic behaviour. This result emphasizes that the type and the nature of the polar end group has a huge impact on the liquid crystalline properties of the molecules.

Keywords

• Liquid crystals
• Chalcone-imine derivatives
• Mesomorphic behaviour
• Rod-like molecule

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