Avaliação do potencial vapocrômico de compostos de coordenação de cobre(II) com ligantes dicarboxilatos e pirazol

Abstract

The coordination compounds formed from copper present a multitude of applications in various segments. Therefore, several reasons favor studies with copper, such as its high availability, low cost and great ease of coordination with diferente different types of binders. For the complexes formed from copper(II), in which the incomplete 3d sublayer and a 4s with only one electron allows hybridization and, therefore, copper complexes can have varied geometries. Ligands, in turn, a fundamental role in the formation of these coordination compounds, as they have the ability to form supramolecules and this offers and provides a potential for the synthesis and applications of vapochromic sensors. In general, it is interesting to study the potential of composite compounds containing copper(II) ions as vapochromic sensors because these devices can be viable and have low manufacturing cost and reversible characteristics in their use, allowing the even have an extended service life. The first stage of this work consisted of the synthesis and analysis of complexes formed from copper(II) containing dicarboxylic ligands and pyrazole: [Cu(ox)2(Pz)2] (C1), [Cu(fum)2(Pz)2] (C2) e [Cu(suc)2(Pz)2] (C3) by the technique of vibrational spectroscopy in the infrared region, which allowed us to infer on the mode of coordination of the dicarboxylates used in the synthesis. The coordination compounds obtained were submitted to solid state reactions in order to verify the vapocomic behavior in the face of exposure to vapours of NH3. By the infrared spectra obtained, it was possible to observe significant changes in the asymmetric and symmetrical stretch bands of dicarboxylates and in the NH stretch of the pirazol group. The exposure of the coordination compounds to NH3 vapors also caused changes in the color of the precursors being evidenced by the displacements in RGB values.