Banca de DEFESA: VITOR FERREIRA DA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : VITOR FERREIRA DA SILVA
DATE: 03/02/2025
TIME: 14:00
LOCAL: videoconferência
TITLE:

SYNTHESIS, PHOTOCHEMICAL STUDY, ACIDOCROMISM, AND INTERACTION WITH METAL CATIONS OF 2-(4-(DECYLOXY)PHENYL-1H-IMIDAZO[4,5-F]PHENANTHROLINE)

KEY WORDS:

N-Heterocycles; Imidazophenanthroline; Fluorescence; Acidochromism; Chemosensors

PAGES: 70
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Orgânica
SPECIALTY: Fotoquímica Orgânica
SUMMARY:

The study of fluorescent organic materials has been of great relevance due to their significant applications in different fields. Within this context, the exploration of structures containing aromatic N-heterocyclic cores stands out, being particularly interesting for acidochromism studies, which have important implications in the field of sensors. This work presents a study of the photochemical and acidochromic properties of the compound 2-(4-(decyloxy)phenyl-1H-imidazo[4,5-f]phenanthroline (1), which was synthesized with yields ranging from 50-65% through two multicomponent protocols. The photochemistry of compound 1 was studied in dichloromethane (DCM), tetrahydrofuran (THF), acetonitrile (ACN), dimethyl sulfoxide (DMSO), and methanol (MeOH), and the maximum absorption wavelengths were found to be between 307-317 nm, indicating the absence of pronounced solvatochromism. On the other hand, the fluorescent capacity of 1 varied considerably depending on the solvent, with higher emissions observed in THF (λEM = 430 nm) and DMSO (λEM = 450 nm), and quantum yield values of up to 31% in the first solvent and 23% in the second. In the other solvents, either the emissions were low, or the material was characterized as non-emissive. The effect of water addition on the emissive behavior of compound 1 in polar solvents was investigated. In MeOH, a slight enhancement in emission was observed with fw = 20%, probably due to an aggregation effect. In ACN, there was a drastic reduction in emission from the initial additions of water. In THF and DMSO, the aqueous mixture up to fw = 20% and fw = 10%, respectively, resulted in a small reduction in emission, but the intensity remained high and red-shifted (λEM = 450 nm for THF and λEM = 453 nm for DMSO). The acidochromism of 1 was evaluated in THF-H2O (fw = 20%) and DMSO-H2O (fw = 10%) mixtures using HCl and NaOH. In an acidic medium, the aqueous mixture of 1 in THF had its emission band at λEM = 450 nm completely suppressed, whereas the aqueous solution of 1 in DMSO not only had its emission band at λEM = 453 nm reduced but also resulted in a new band at λEM = 389 nm. The study in a basic medium revealed that the THF-H2O system had its band at λEM = 467 completely suppressed. In contrast, the DMSO-H2O system showed a decrease in the band at λEM = 450 nm and the appearance of another band at λEM = 525 nm. The acidochromism was further confirmed through 1H NMR analysis, which showed significant changes in the spectrum. Additionally, 1, when adsorbed onto filter paper, demonstrated the ability to detect HCl and NH3 vapors. The interaction of 1 with 3,4,5-tridodecyloxybenzoic acid was evaluated using UV-vis, fluorescence, and 1H NMR. The results are promising, as it was observed that the interaction induces an increase in fluorescence, and changes were noted in the 1H NMR spectrum, indicating the formation of a molecular salt. The derivative 1 was also evaluated as a chemosensor for cations. However, it showed low selectivity towards metals.

COMMITTEE MEMBERS:
Externo à Instituição - LUÍS ALEXANDRE ALMEIDA FERNANDES COBRA BRANCO - NOVA
Externo à Instituição - ANDRÉ HERCULANO DE OLIVEIRA - UFRN
Interna - 349770 - DULCE MARIA DE ARAUJO MELO
Presidente - 1803692 - FABRICIO GAVA MENEZES
Interno - 1198847 - JOSE LUIS CARDOZO FONSECA