1, 5-diaminotetrazole at conditions of its interaction with chalcones (1, 3- diphenylpropenones) in hot DMF undergoes Dimroth rearrangement to 5- tetrazolylhydrazine, which results in formation of 1-(5-tetrazolyl)-3, 5-diaryl-Δ2-pyrazolines (I). Structure of the obtained products was confirmed by their parallel synthesis and X-ray structural analysis. Unusual fluorescence behavior of the tetrazolopyrazolynes in polar ...