Banca de DEFESA: JOSE VITOR DE SOUZA MEDEIROS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : JOSE VITOR DE SOUZA MEDEIROS
DATE: 05/06/2023
TIME: 08:00
LOCAL: videoconferência
TITLE:

EVALUATION OF THERMAL AND OPTICAL PROPERTIES OF NOVEL FLUORESCENT 2,4,6- TRIARYLPYRIDINE DERIVATIVES

KEY WORDS:

Heterocycles; 2,4,6-triarylpyridine; organoelectronics; liquid crystals; fluorescence

PAGES: 90
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Orgânica
SPECIALTY: Síntese Orgânica
SUMMARY:

The world has sought to develop new functional advanced material for many applications in the optical-electronic fields, and among them, liquid crystals (LC) are widely employed as fundamental components in screens and displays. This work presents the synthesis and structural characterization as well as the investigation of photo- physical and thermal properties of a new 2,6-bis(4-(dodecyIoxy)phenyl)-4-(4-X-phenyl)pyridines (X = H, 3a; F, 3b; NO2, 3c; 2-thiophen, 3d; Ph, 3e; OCH3, 3f; OC12H25, 3g; carbazole) and 2,4,6-tris(3,4-bis(dodecyloxy)phenyl)pyridine (3h), aiming new fluorescent liquid crystals. These molecules have π-extended heterocyclic nuclei as rigid core and peripheral dodecyloxy chains, being structurally adequate for this proposal. Target molecules 3a-3g were obtained in moderate yielding (33-78%) by a multicomponent protocol based on combination of 1-(4-(dodecyloxy)phenyl)ethanone, 4-X-benzaldehyde and ammonium acetate, in DMF and presence of cobalt chloride. These products were properly characterized by 1H and 13C nuclear magnetic resonance (NMR) and infrared (IR) spectroscopies. Polarized optical microscopy (POM) and differential scanning calorimetry (DSC) indicated that, under heating, compound 3g showed a crystal to crystal transition at 60oC, until 95oC, when becomes isotropic liquid. This behavior was also evidenced by POM on cooling. For compound 3h, although a rationalized spherulitic texture was confirmed by POM, formation of mesophase was not evidenced. The pyridine derivatives showed maximum in absorption bands between 258 nm and 377 nm, and fluriescence in the blue/violet region in solution, emission between 370 and 391 nm, and also in the solid state. The colors associate to emission were confirmed using a chromatographic diagram software based on fluorescence data. At this moment, photo-physical and thermal analysis of target molecules are being carried out.

COMMITTEE MEMBERS:
Presidente - 1803692 - FABRICIO GAVA MENEZES
Interno - 1859346 - MIGUEL ANGELO FONSECA DE SOUZA
Externo à Instituição - RODRIGO CRISTIANO - UFPB