The position of NH2-subsituted group controlled the luminescent properties based on 4-amino-4H-1,2,4-triazole: Syntheses, crystal structures and Hirshfeld analyses

The tunable photoluminescent materials has drawn extensive attention in recent years. The position of the substituents tuned the luminescent materials are one of attractive methods. Herein, we present a feasible and facile strategy to achieve a 4-amino-1,2,4-1H-triazole-based organic materials. A set of compounds based on 4-amino-4H-1,2,4-triazole group, namely, x,x'-(4-amino-4H-1,2,4-triazole-3,5-diyl)dianiline [x ​= ​2 (1), x ​= ​3 (2), x ​= ​4 (3)] (the formulas are C14H14N6, C14H14N6 and C14H16N6O for compounds 1–3, respectively), were obtained. The title compounds 1–3 have been characterized by IR, UV–Vis, 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⋯O/N) and C–H … π can be obviously found. The order of the packing interactions is represented as the following: 2 ​> ​3>1. The Hirshfeld surface analyses reveal that the contribution order of the H⋯H bond contacts in compounds 1–3 is listed: 2 ​> ​3>1, which is in a good agreement with that of the stacking interactions. The solid-state luminescent spectra of 1–3 show that the emission maxima are observed at 404, 377 and 457 ​nm, respectively, where the order of the peaks is represented as 3 ​> ​1>2. The Hirshfeld surface analyses show that the contribution order of the C⋯H/H⋯C close contacts is listed: 3 ​> ​1>2, which is in a good accordance with that of the fluorescent maxima.