Esquaramidas e seus derivados: síntese, estudo teórico e fotoquímico de suas propriedades fotoluminescentes

Abstract

The present Master's dissertation presents the results of the synthesis, characterization and the photoluminescent properties of molecular hybrids, donorsacceptors (D-A), and donors-acceptors-donors (D-A-D), which were obtained through the condensation between aromatic amines Ar-NH2 (electron-donating subunits, D) and dimethyl squarate (acceptor unit, A). Twelve squaramides, including six monosubstituted and six bis-substituted, were prepared with good yields (80-90%). Among these squaramides, one mono-substituted and two bis-substituted compounds are novel through the condensation reaction between dimethyl squarate and aromatic amines. All prepared precursors and intermediates were characterized by hydrogen and carbon-13 nuclear magnetic resonance spectroscopy, and high-resolution mass spectrometry. The squaramides exhibited absorptions in the ultraviolet region (220-400 nm) and fluorescent emissions in the visible region (400-700 nm) and near-infrared region (700-800 nm). The photophysical study of squaramide derivatives was also performed in DMSO solution. Significant changes were observed in the photophysical properties of these derivatives, such as increased intensity and bathochromic shift in both absorbance and emissions. Computational photophysical studies were carried out at the TPSSh/def2-TZVP/CPCM(DMSO) level for absorption and emission energies, as well as optimization of the geometries of the ground state S0 and excited state S1.