Decomposition mechanism and kinetics of zinc–isophthalate complex with 2,2’-dipyridylamine as a precursor for obtaining nanosized zinc oxide

Abstract

Studies related to the synthesis of nanosized ZnO as the antibacterial agent have become an interdisciplinary area gathering chemists, physicists, biologists, and medics. The broad scope of materials based on ZnO resulted in the development of various techniques for its preparation. Considering the dependence of particle shape and size onto physical and chemical properties of ZnO, the synthesis procedure is of major importance. In this work, an unconventional methodology of synthesis is proposed for obtaining nanosized ZnO. Polymeric zinc complex containing 2,2’-dipyridylamine (dipya) and dianion of 1,3-benzenedicarboxylic acid (ipht), [Zn(dipya)(ipht)]n, was used as precursor. Besides the crystal structure of [Zn(dipya)(ipht)]n which was already published [1], the luminescent properties are presented in this work. Also, the amazing antibacterial activity of this precursor prompted us to investigate the relationship between the crystal structure and thermal properties, especially if we bear in mind the lack of similar studies in the literature. Therefore, the mechanism and kinetics of its degradation was investigated under nonisothermal conditions in nitrogen and air atmospheres. Degradation enthalpies, thermodynamic activation parameters, pre-exponential factor, A, and the apparent activation energy, Ea, were determined for each step using Kissinger’s and Ozawa’s equations. The complexity of degradation steps has been analyzed using isoconversional methods. TG/DCS data were collected at four different heating rates: 10, 15, 20 and 25 ºC min –1 , while the formation of nanosized ZnO was confirmed using XRPD and FESEM techniques. The influence of precursor on the crystallite size and morphology of the resulting ZnO along with its antibacterial activity was examined. The obtained results will be discussed and compared.