Novel phthalocyanines bearing 1,2,4 triazole substituents: Synthesis, characterization, photophysical and photochemical properties

Quantum chemical studies on structural, spectroscopic, nonlinear optical, and thermodynamic properties of the 1,2,4-triazole compound

In this study, the structure of 4-[4-(diethylamino)-benzylideneamino]-5-benzyl-2H-1,2,4-triazol-3(4H)-one (DBT) was examined through spectroscopic and theoretical analyses. In this respect, the geometrical, vibrational frequency, 1H and 13C-nuclear magnetic resonance (NMR) chemical shifts, thermodynamic, hyperpolarizability, and electronic properties including the highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) energies of DBT as a potential non-linear optical (NLO) material were investigated using density functional theory at the B3LYP level with the 6-311G basis set. 1H and 13C-NMR chemical shifts of DBT with the gauge-invariant atomic orbital and continuous set of gauge transformation methods (in the solvents) were estimated, and the computed chemical shift values displayed excellent alignment with observed ones. Time-dependent density-functional theory (TD-DFT) calculations with the integral equation formalism polarizable continuum model within various solvents and gas phases in the ground state were used to evaluate UV-vis absorption and fluorescence emission wavelengths. Thermodynamic parameters including enthalpy, heat capacity, and entropy for DBT were also calculated at various temperatures. Moreover, calculations of the NLO were carried out to obtain the title compound’s electric dipole moment and polarizability properties. To illustrate the effect of the theoretical method on the spectroscopic and structural properties of DBT, experimental data of structural and spectroscopic parameters were used. The correlational analysis results were observed to indicate a strong relationship between the experimental and theoretical results.

Highly Luminescent 4H-1,2,4-Triazole Derivatives: Synthesis, Molecular Structure and Photophysical Properties

An alternative approach to the Suzuki cross-coupling reaction is used to synthesize a series of new luminophores based on 4-alkyl-4H-1,2,4-triazole cores conjugated via 1,4-phenylene linker to fused-bicyclic and tricyclic aromatic, or heteroaromatic arrangements. The described methodology allows one to conduct the coupling reaction with the use of commercially available boronic acids in the presence of conventional solvents or ionic liquids and produced excellent yields. It was found that the use of ultrasounds or microwaves significantly accelerates the reaction. The obtained compounds exhibited high luminescent properties and a large quantum yield of emitted photons. The X-ray molecular structures of three highly conjugated 4H-1,2,4-triazole representatives are also presented.