Condensation Polymers of Terephthalic Acid and 1,4-Diaminobutane and Their Schiff Base Complexes

Amino-terminated oligomeric poly(tetramethylene terephthalamide) (PTTA) was prepared by condensation of terephthalic acid and 1,4-diaminobutane using phosphorylation technique. Schiff base complexes of this polyamide were synthesized with salicylaldehyde and 2-hydroxy-1-naphthaldehyde complexes of Co(II), Ni(II), and Cu(II). The polyamide as well as Schiff base complexes were characterized by elemental analysis, IR spectroscopy, and magnetic susceptibility measurements. Thermal stabilities of ligand and its various complexes were compared by thermogravimetric analysis. 1. Introduction Polyamides, the condensation polymers of dicarboxylic acids and diamines, are frequently referred to as nylons, an important group of polymers which can be synthesized using phosphorylation technique [1]. Oligomers based on these polyamides having reactive terminals are of great importance in order to yield materials with novel properties. Most of the polyamides do not withstand elevated temperature for a longer time. We have tried to get thermally resistant polyamide-metal complexes by inserting metal ions in ligands through the formation of Schiff’s base complexes. We have reported Schiff base complexes with oligomeric poly(methylene diphenylene terephthalamide) [2]. In the present communication we are reporting Schiff base complexes of amino-terminated low molecular weight poly(tetramethylene terephthalamide), PTTA, with salicylaldehyde and 2-hydroxy-1-naphthaldehyde complexes of Co(II), Ni(II), and Cu(II). Various Schiff bases involving aldehydes with aromatic diamines are extensively studied by numerous workers and are critically reviewed and reported for their biological properties, such as antibacterial and antifungal activities [3–5]. Few polymeric complexes with Schiff’s base structures have been synthesized from aromatic amines and phenolic aldehydes. These metal complexes have been widely studied because they have anticancer and herbicidal applications [6–8]. 2. Materials and Methods 2.1. Materials The materials of analytical quality or equivalent grades were used. Salicylaldehyde was from S. Merck., India, and 2-hydroxy-1-naphthaldehyde (AG) was from Fluka. 1,4-diaminobutane of AR grade was obtained from E. Merck, India, and was used without further purification. Dimethyl formamide (DMF), dimethyl sulphoxide (DMSO), and pyridine were GR grade products of Qualigens, Glaxo, India, and were distilled before use. Acetates of cobalt(II), nickel(II), and copper(II) (all of AR grade from E. Merck, India) were used as such. 2.2. Synthesis of Amino-Terminated Oligomeric