Síntese e propriedades ópticas de materiais moleculares avançados derivados do heterociclo 2,4,6-triarilpiridina

Abstract

The search for new advanced materials for application in optical-electronic devices is a promissory research field in organic chemistry. Liquid crystals are largely employed in electronic devices, such as screen and display components. Structurally, heteroaromatic systems are commonly explored as rigid nuclei in liquid crystals, whereas peripheric aliphatic long chains characterize the flexible units. This combination may allow the liquid crystal state (called mesophase), which presents solid and liquid properties, such as birefringence and fluidity, respectively. Furthermore, these molecular systems may also present luminescence, which is also relevant for application in electronic devices. The main goal of this work is synthesis and structural characterization, as well as the study of optical and chemical properties of a new pyridine derivative, 2,6-bis(4-(dodecyloxy)phenil)-4-(thiophen-2-yl)pyridine (1), as a potential liquid crystal. This target-molecule was obtained in moderate yield by a multicomponent protocol involving 1-(4-(dodecylocy)phenyl)ethanone, thiophene-2-carbaldehyde and ammonium acetate, e properly characterized by infra-red (IR), 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopies. Compound 1 showed absorption bands, having their maximum at 302 nm, 341 nm and 357 nm. Both naked eye and fluorometry spectroscopy analysis showed that compound 1 presented fluorescence with emission in the blue region. Optical polarized microscopy and DSC analysis showed that compound 1 is not thermotropic liquid crystal, presenting only one phase transition (melting at 87,3 oC). However, despite the mesophase absence, the study herein presented is a relevant advance for the development of molecular materials based on 2,4,6-triarylpyrydine system, leading to promissory perspectives for future works.