Propriedades vibracionais de derivados do ácido de Meldrum complexados com Zn e Cu por cálculos DFT e espectroscopias Raman e infravermelho

Abstract

In this study, four derivatives of Meldrum’s acid complexed with Zinc and Copper were characterized: C24H24N4O10Zn, C24H24N4O10Cu, C18H18N6O8S2Cu, and C28H32N4O8Cu. Spectroscopic analyses of FT-IR and FT-Raman, combined with Density Functional Theory (DFT) using the B3LYP/6-31G (d,p) method/basis set, were performed to evaluate information on molecular conformational preferences and vibrational assignments. The results showed that the aminomethylene chain played an important role in the complexation process. In addition, the main bands of aromatic rings were shifted relative to traditional regions. Five bands, called the Meldrum signature, were also identified that characterize the existence of the Meldrum ring in the IR spectrum of the compounds. Comparative analysis of the structural geometrical parameters of uncomplexed and complexed Meldrum’s acid derivatives, as well as a complete analysis of the vibrational modes, were provided for the Meldrum’s acid derivatives complexed with Zinc and Copper. In some cases, molecular conformational changes were observed due to the presence of the metal in the aromatic ring oxygenation form. A comparative table of the IR active modes of Copper complexes was also provided. These results suggest the possibility of using these compounds as potential therapeutic agents or in electrochemical catalysis applications.