Study of the optical properties of photosensitizers: Triplet formation, two-photon absorption and molecular interaction

• Grant number: 23/05917-1
• Support Opportunities: Scholarships in Brazil - Master
• Start date: August 01, 2023
• End date: July 31, 2025
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Leonardo de Boni
• Grantee: Diego França de Oliveira
• Host Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Associated research grant: 18/11283-7 - Nonlinear photonics: spectroscopy and advanced processing of materials, AP.TEM

Abstract

The work that will be developed in this project aims to analyze photophysical properties of a group of photosensitizing molecules with potential for application in photodynamic therapy. The molecules that will be studied include some already consolidated in the area, in addition to new molecules. The unpublished porphyrins do not present detailed studies regarding their absorption and fluorescence with temporal resolution, therefore, we intend to describe their decay rates in solution, including their intersystem crossing rate (triplet formation). Both classical and unpublished molecules also lack detailed studies regarding their two-photon absorption, so this project also aims to determine the cross-section spectrum of two-photon absorption. The photophysical information acquired from the molecules will be crossed with their structural molecular properties, in order to understand the relationship that exists between these factors.In addition to the spectroscopic analysis of these compounds, we intend to study how the optical properties of these molecules change as a result of intermolecular interactions that they can perform with other molecules in solution. The photosensitizers will be placed in solution with controlled concentration of secondary molecules and it will be observed how the absorption and relaxation properties change as a function of the concentration of these compounds. This analysis aims at a better understanding of the molecular mechanisms that occur in biological environments, in which there is interaction with biomolecules, and a greater understanding of the factors that can help or hinder the efficiency of a photodynamic process.