ABSTRACT

In the present work two homologue series of four-ring azo/ester/imine compounds; namely, 4-(4′–alkoxy–phenylazo) phenyl–4′′–(benzylidene–amino) benzoate, In, and 4–(4′–alkoxy–phenylazo) phenyl–4′′–[(pyridin-3–ylmethylene)–amino] benzoate, IIn, were prepared and investigated for their mesophase behaviour. In these two types of homologue series, the length of the terminal alkoxy group (n) varies between 6 and 16 carbons. Compounds prepared in both series were structurally characterised via thermogravimetric and elemental analyses, FTIR, ¹H-NMR, and mass spectroscopy. Their mesophase transition temperatures were determined by differential scanning calorimetry (DSC), whereas, the type of the mesophase was identified by polarised light microscopy (PLM). The molecular structure–property relationship was conducted aiming to investigate the effect of replacing the terminal phenyl group in In with a pyridyl one in IIn, in addition to the effect of variation of the alkoxy chain length. Aiming to investigate the effect of inversion of the methineazo group on the mesophase behaviour of the compounds, a comparison was made between the prepared series of compounds (In) with previously prepared four rings 4-(4′-alkoxyphenylazo)–phenyl 4′′–phenyliminomethyl–benzoate phenyl-4ʹ-(4′′-alkoxyphenylazo) benzoate, IIIn. Finally, the mesophases of series IIn were compared with their corresponding three-ring analogues, 4-(4′-alkoxy phenyl −4′′-[(pyridin-4-ylmethylene)–amino] benzoate analogues (IVn).

摘要

在目前的工作中，四环偶氮/酯/亚胺化合物的两个同系物；即，4-(4'-烷氧基-苯基偶氮)苯基-4''-(亚苄基-氨基)苯甲酸酯，I n和 4-(4'-烷氧基-苯基偶氮)苯基-4''-[(pyridin-3 -ylmethylene)-amino] 苯甲酸酯, II n , 被制备并研究了它们的中间相行为。在这两种类型的同系物系列中，末端烷氧基 ( n ) 的长度在 6 到 16 个碳之间变化。通过热重分析和元素分析、FTIR、¹对两个系列制备的化合物进行结构表征H-NMR 和质谱。它们的中间相转变温度由差示扫描量热法 (DSC) 确定，而中间相的类型由偏光显微镜 (PLM) 确定。进行分子结构-性质关系的目的是研究用II n 中的吡啶基取代I n 中的末端苯基的影响，以及烷氧基链长度变化的影响。为研究甲胺偶氮基的反转对化合物中间相行为的影响，对制备的系列化合物（I n) 与先前制备的四个环 4-(4'-烷氧基苯基偶氮)-苯基 4''-苯基亚氨基甲基-苯甲酸酯苯基-4'-(4''-烷氧基苯基偶氮)苯甲酸酯，III n。最后，将II n系列的中间相与其相应的三环类似物 4-(4'-烷氧基苯基 -4''-[(pyridin-4-ylmethylene)-amino] 苯甲酸酯类似物 ( IV n ) 进行比较。