Synthesis, spectroscopic properties and theoretical studies of bis-Schiff bases derived from polyamine and pyrazolones

A series of novel bis-Schiff base were synthesized from 1-aryl-3-methyl-4-benzoyl-5-pyrazolones and diethylenetriamine (or triethylenetetramine) as the starting materials. All of these bis-Schiff bases were characterized by means of NMR, IR, and MS. The UV–vis absorption spectra and fluorescent spectra of these bis-Schiff bases were also measured. Moreover, the B3LYP/6-31G(d) method was used to optimize the ground state geometry of the bis-Schiff bases; and the UV–vis spectroscopic properties of the products were computed and compared with corresponding experimental data based on cc-pVDZ basis set of TD-B3LYP method. It has been found that all of these bis-Schiff bases show a remarkable absorption peak in a wavelength range of 270–340 nm; and their maximum emission peaks are around 348 nm.

Graphical abstractA series of novel bis-Schiff bases containing pyrazole group were synthesized using polyamine and 1-aryl-3-methyl-4-benzoyl-5-pyrazolones as the starting materials. The ultraviolet absorption and fluorescence spectra of these compounds have been studied systematically. Moreover, the B3LYP/6-31G(d) method was used to optimize the ground state geometry of the bis-Schiff bases; and the spectroscopic properties of the products were computed based on cc-pVDZ basis set of TD-B3LYP method.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A series of novel Schiff bases containing pyrazole group were synthesized and characterized. ► The UV–vis spectra and fluorescent spectra of various as-synthesized products were measured. ► The B3LYP/6-31G(d) method was used for the optimization of the ground state geometry of the Schiff bases. ► The spectroscopic properties of the Schiff bases were computed based on cc-pVDZ basis set of TD-B3LYP method.