Biotióis; 2,3-dicloro-6,7-dinitroquinoxalina; Quimiodosímetro; Estudo computationa
Biothiols; 2,3-dichloro-6,7-dinitroquinoxaline, Chemodosimeter; Computation study.
Biothiols, such L-cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), are highly relevant species in many biological processes, and therefore, the development of methodologies for the selective detection of these biothiols is a relevant research field. This work aims to provide theoretical support to the results obtainted in our research group for the L-cysteine (Cys) sensing ability of the chemodosimeter 2,3-dichloro-6,7-dinitroquinoxaline (DCDNQX), with an extension for its reactions with Hcy and GSH. The method M06-2X with 6-311+G (2d,p) basis set was applied for all calculations. They were evaluated several mechanistic proposals taken into account the versatility of Cys, Hcy and GSH as nucleophiles, including the possibility of nucleophilick attack by amino ad/or thiol groups, for both mono- and dissubstitution, including intramolecular cyclizations. Geometric parameters, inclding transition states for all molecules and reactions were optimized searching for thermodynamics and kinetics information. The results indicated the preference for the S- over N-attack, and the cyclized product being the most stable. The effect of structure on intramolecular cyclization was also studied.