DESVENDANDO REAÇÕES E COLISÕES: COMO A QUÍMICA QUÂNTICA COMPUTACIONAL ASSISTE NO ENTENDIMENTO DAS FRAGMENTAÇÕES NA ESPECTROMETRIA DE MASSAS TANDEM POR COLISÃO

UNVEILING REACTIONS AND COLLISIONS: HOW COMPUTATIONAL QUANTUM CHEMISTRY SUPPORTS THE UNDERSTANDING OF COLLISION-INDUCED DISSOCIATION IN TANDEM MASS SPECTROMETRY. Tandem mass spectrometry (MS/MS) occupies a central position in experimental and analytical sciences, with collision-induced dissociation (CID) standing out as a fundamental technique for investigating molecular structures. In this process, molecular ions collide with a neutral gas, generating fragments that enable the elucidation of dissociation mechanisms. However, achieving a rational understanding of the collision phenomenon and its physicochemical implications – particularly the fragmentation channels and mechanisms – remains a theoretical challenge, especially when comparing models with experimental data obtained as a function of collision energy, as in energy-resolved mass spectrometry (ERMS). In this context, theories such as the transition state theory (TST) and the Rice-Ramsperger-Kassel-Marcus (RRKM) model have become well established for providing robust descriptions of the physicochemical processes involved in CID. The foundation of their success lies in the application of quantum mechanics, particularly computational quantum chemistry. This integration makes it possible to predict spectra, estimate energy-dependent intensities, and, above all, model dissociation channels and mechanisms and determine reaction rate constants. Thus, this work presents a synthesis of the contributions of quantum chemistry to the theory applied to CID, highlighting its essential role in advancing understanding and consolidating theoretical foundations for mass spectrometry.