The substituent effect on the luminescent properties of a set of 4-amino-4H-1,2,4-triazole: Syntheses, crystal structures and Hirshfeld analyses

A set of compounds based on 4-amino-4H-1,2,4-triazole group, namely, 4,4'-(4-amino-4H-1,2,4-triazole-3,5-diyl)dibenzoic acid (1), 4,4'-(4-amino-4H-1,2,4-triazole-3,5-diyl)dianiline (2), 4,4'-(4-amino-4H-1,2,4-triazole-3,5-diyl)diphenol (3), were obtained through reacting different aromatic nitrile and hydrazine under the solvothermal conditions, respectively. The title compounds 1-3 have been characterized by IR, UV-Vis, H-1 NMR, C-13 NMR, element analysis (EA), single crystal X-ray diffraction, and powder X-ray diffraction (PXRD). In these compounds, a plenty of hydrogen bonds (C/N-H center dot center dot center dot O/N) and C-H center dot center dot center dot pi can be obviously obtained, through which a three-dimensional framework will be constructed. The solidstate luminescent spectra of 1-3 show that the emission maxima are observed at 398, 464 and 402 nm, respectively. The order of maximal peaks is 1<3<2. The Hirshfeld surface analyses confirm that the order of the contribution of C center dot center dot center dot H/H center dot center dot center dot O and H center dot center dot center dot H contacts is 1<3<2, which is in a good accordance with that of the luminescent bands. (C) 2021 Elsevier B.V. All rights reserved.