LAUSR

Abstract A solvent-free solid state method has been developed to synthesize three series of substituted azole derivatives (including 1,3,4-oxadiazole, 1,3,4-thiadiazole and 1,2,4-triazole) in high yields by condensation cyclization of N,N′-bishydrazide derivatives with corresponding cyclization agents, respectively. This general method avoids the use of organic solvents, saves cost and resources, simplifies post-processing and increases reaction rates. These compounds have been fully characterized by 1H NMR, 13C NMR, elemental analysis and MS. The structure of 2,5-di (4-tertbutylphenyl)-1,3,4-oxadiazole has been determined by single crystal X-ray diffraction analysis. The cell parameters are as follows: monoclinic crystal system, Cc space group, a = 18.735 (2) A, b = 6.3375 (8) A, c = 16.824 (2) A and α = γ = 90°; β = 98.292 (2). The electronic absorption and fluorescent properties of these compounds have been systematically investigated for the first time. The relationships between heterocyclic structures and photophysical properties have been discussed. The alteration of emission and absorption wavelengths can be elucidated by hybrid atoms' electronegativity and Substituents' Hammett constants. This approach proposes a novel insight to provide a great number of novel substituted azole derivatives with good photophysical properties by a general green method.