Co - ordination polymers derived from pyromellitic diamic acid : synthetic , spectral , magnetic , thermal and biological aspects

Introduction The design of metal organic co-ordination polymeric materials have been deeply researched. In recent years, the studies of co-ordination polymers have made much progress. Such polymers are prepared by polymerization of bis ligand and metal ions. Most of the co-ordination polymers are reported based on bis-salicylic acid, bis-salicyaldehyde and bis-oxine.[16] One of the area in which the co-ordination polymer formation through bisamic acid has not been much developed except few instances. Bisamic acid based on maleic anhydride, [7-9] amic acid based on phthalic anhydride[10-13] are only such type of co-ordination compound / polymers based on amic acid. More particularly, multicarboxylate material i.e. 1,2,4,5-benzene tetra carboxylic acid has been shown to be good building blocks in the design of metal organic materials with desired topologies owing to their rich co-ordination modes. Therefore, the dianhydride of 1,2,4,5-benzenetetracarboxylic acid known as pyromellitic dianhydride–PMDA has been selected for the further work. Literature survey also reviewed that, the co-ordination metal polyamide based on bisamic acid of pyromellitic dianhydride (PMDA) has not attracted any attention. Hence, the initial work in this direction has been reported by us recently. [14] This prompted us to extend our work by using other auxiliary ligand such as 2,5-bis (phenylcarbamoyl)terephthalicacid. Considering the special biological activity of these polymeric complexes along with their magnetic properties, thermo gravimetric analysis and polymeric property, we focused our work on this ligand by complexation using Cu(II), Co(II), Ni(II), Mn(II) and Zn(II) metal ions. The synthetic route is shown in Scheme-1. Experimental details Material All the chemicals such as 1,2,4,5-benzenetetracarboxylic dianhydride (pyromellitic dianhydride-PMDA) (m.p. 397400 ̊C) of Fluka Analytical-Japan , Aniline of SD fine chemicals-Mumbai and Cu(II), Co(II), Ni(II), Mn(II) and Zn(II) metal ions salt of Merck Laboratory and SD fine chemicals used were of reagent grade. Solvents are dried and distilled before use according to standard procedures. Measurements Infrared (IR) spectra of all the samples were scanned on a Nicolet-760 FTIR spectrophotometer. H NMR and C NMR were recorded on Bruker spectrophotometer (400 MHz). Elemental analysis of ligand and its co-ordination polymers were carried out on a Thermofingan flash 1101EA (Italy). The metal content of the co-ordination polymers were performed by decomposing a weighed amount of co-ordination polymer followed by the complexometric titration with EDTA(disodiumethylenedi aminetetra acetate).[15] The number average molecular weight of polymers was determined by method reported.[16] Magnetic susceptibility measurements of polymers were carried out at room temperature by the Gouy method. Molar susceptibities were corrected for diamagnetism of component atoms using Pascal’s Constant. [17] The solid diffuse reflectance spectra of polymers and ligand samples were recorded on a Beckman DK-2A spectrophotometer. Thermo gravimetric analysis was carried on Perkin Elmer TGA analyzer. Antibacterial activity of ligand and polymers were studied against gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) and gram-negative bacteria (E.coli, and Salmonella typhi). The fungicidal activity of all the compounds was studied at 1000 ppm concentration in vitro. Plant pathogenic organisms used were Penicillium expansum, Botrydepladia thiobromine, Nigrospora Sp., Trichothesium Sp.. The percentage inhibition for fungi was calculated after five days using the formula given Percentage of inhibition = 100(X-Y) / X. Where, X: Area of colony in control plate, Y: Area of colony in test plate Preparation of 2,5-bis(phenylcarbamoyl)terephthalicacid (bpctpa) The bpctpa was prepared by method reported.[18] According to this method, a mixture of 1,2,4,5-