Full text
| |
| Author(s): |
Gabriel de Oliveira Campos
Total Authors: 1
|
| Document type: | Master's Dissertation |
| Press: | São Carlos. |
| Institution: | Universidade de São Paulo (USP). Instituto de Física de São Carlos (IFSC/BT) |
| Defense date: | 2025-03-06 |
| Examining board members: |
Cleber Renato Mendonça;
Márcio André Rodrigues Cavalcanti de Alencar;
Pablo José Gonçalves
|
| Advisor: | Cleber Renato Mendonça |
| Abstract | |
Great importance has been attributed to organic molecules in photonics research. Part of this can be connected to the wide range of applications these compounds have, ranging from the monitoring of biological processes through fluorescent probes to bioimaging via two-photon absorption fluorescence microscopy. In this context of innovation, the imidazopyridine group emerges as an excellent candidate due to its characteristics of: high electronic delocalization and the formation of tautomers in excited states, leading to the appearance of interesting optical responses. In this regard, the present study aims to evaluate the linear and nonlinear absorptive characteristics of a series of sulfonated imidazopyridines, along with the investigation of the dynamics of their excited states. For this, UV-Vis spectroscopy, fluorimetry, time-resolved fluorescence, Z-scan, and transient absorption experiments were conducted, complemented by computational simulations using Density Functional Theory (DFT). The results presented here show good agreement between the experimentally and simulated obtained molar absorptivity values and dipole moments, the presence of fluorescence in a subset of molecules with lifetimes ranging from 0.7 ns to 1.3 ns, and fluorescence quantum efficiency ranging from 0.5% to 3.6%. These results also show high two-photon cross-sections (~50 GM), explained by both the donor and acceptor nature of the added peripheral groups and the cooperation between two-photon absorption between the S0 → S1 levels and one-photon absorption between the S1 → Sn levels. In this sense, the present work represents an advancement in the understanding of the linear and nonlinear optical properties of imidazopyridines, opening the door for the engineering of new optimized compounds with potential applications. (AU) | |
| FAPESP's process: | 22/16848-8 - Analysis of the influence of different peripheral groups on the multiphoton absorption of sulfonated imidazopyridines |
| Grantee: | Gabriel de Oliveira Campos |
| Support Opportunities: | Scholarships in Brazil - Master |