Reatividade de clorido complexos terpiridina de rutênio (II) coordenados a ligantes diimina: Estudo cinético e termodinâmico de aquação e interação com DNA

Abstract

Metal complexes have garnered significant interest in bioinorganic chemistry due to their chemical properties and potential biological applications. In particular, ruthenium(II) polypyridyl complexes stand out for their propensity to interact with DNA, making them promising candidates for studies in antitumor models. Furthermore, their remarkable photochemical and photophysical properties expand their potential applications. The development of these compounds as drug candidates requires an understanding of how geometry and co-ligands influence their chemical reactivity and biological activity. In this study, two complexes of the type [RuIICl(bd)(tpy)]PF6 and [RuIICl(bdq)(tpy)]PF6 — where tpy = 2,2':6',2''-terpyridine, bd = o-phenylenediamine, and bdq = 3,4-diaminobenzoic acid — were synthesized and characterized, along with their corresponding aqua complexes, [RuII(OH2)(bd)(tpy)](PF6)2 and [RuII(OH2)(bdq)(tpy)](PF6)2. To investigate the kinetics of the spontaneous aquation reaction of the chlorido complexes, spectroscopic variation studies in the UV-visible region and HPLC analyses were performed, revealing that [RuIICl(bd)(tpy)]PF6 exhibits a higher rate constant than the complex bearing the bdq ligand. Experimental results were complemented by theoretical calculations to determine the aquation rate constants and activation parameters. An associative mechanism was proposed for the aquation reaction, where the steric effect of the –COOH substituent influences the entry of the aqua ligand. To elucidate their interaction with biomolecules, spectroscopic studies demonstrated that both complexes interact with fs-DNA via intercalation, with apparent binding constants of (2.39 ± 0.11)×106 and (1.33 ± 0.33)×106 L mol–1 for [RuIICl(bd)(tpy)]PF6 and [RuIICl(bdq)(tpy)]PF6, respectively. Antiviral assays revealed that [RuIICl(bd)(tpy)]PF6 exhibited greater efficacy in inhibiting the Zika and Chikungunya viruses.