Effects of hybrid QM/MM solvation and ions interactions on spectroscopy and photophysical processes of sulfonamides tautomers

• Grant number: 25/13459-9
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: December 01, 2025
• End date: July 31, 2026
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
• Principal Investigator: Roberto Luiz Andrade Haiduke
• Grantee: José Luiz Felix Santos
• Supervisor: Adrian Roitberg
• Host Institution: Instituto de Química de São Carlos (IQSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Institution abroad: University of Florida, Gainesville (UF), United States
• Associated to the scholarship: 22/14780-7 - Theoretical study of the effects of hydrogen bonds and interactions with ions on the ground, electronically excited states and energetic barriers of the sulfonamide photodegradation reaction, BP.DR

Abstract

Sulfonamides (SAs) are synthetic antibiotics that exhibit potencial threat to aquatic environments and human healthy. Moreover, SAs pose a complex tautomeric behavior in aqueous environments, withsignificant implications for their photochemical and photophysical properties. This project aims toinvestigate how explicit solvation and interactions with environmentally relevant metal cations (e.g., Ca²¿, Zn²¿, Mg²¿) modulate the structural and spectroscopic features of SA tautomers in solution. Hence, the study integrates classical molecular dynamics (MD) with quantum mechanical/molecularmechanical (QM/MM) simulations, along with excited-state electronic structure methods. The project also explores nonadiabatic molecular dynamics (NAMD) to understand how solvent effects and ionic interactions influence the photophysical processes (e.g., vibronic couplings, internal conversion and intersystem crossing). The research will provide a detailed molecular-level understanding of the behavior of SAs under physicochemical and environmental conditions. The outcomes are expected to contribute to the rational design of photodegradation strategies and enhance the predictive capabilities of hybrid QM/MM models for complex molecular systems.