Synthesis and Fluorescent Behaviour of 2‑Aryl-4,5-dihydro‑1<i>H</i>‑1,2,4-triazoles

A series of new 4,5-dihydro-1H-1,2,4-triazoles was synthesized from amidrazones and acetylenedicarboxylic acid esters in the presence of pyridine in toluene. The synthesized compounds were characterized by 1H, 13C NMR, FT-IR spectral analyses and XRD data. Optical studies revealed that most of the compounds reported here exhibited emission of blue or green-yellow light upon irradiation in acetone and showed Stokes shifts in the region of 70–96 nm and quantum yields of up to 45%. The interpretation of the experimental findings was supported by state-of-the-art quantum mechanical calculations.