A new and highly efficient microwave promoted N-alkylation of triazolo-quinazolinones was developed by treating various phenyl-substituted heterocyclic amines with benzyl chloride using K2CO3 as a base in the presence of DMF. Also the heterocyclic amines were synthesized by condensing the 3-amino-1,2,4-triazole substituted benzaldehydes and 1,3-cyclohexanedione in the presence of microwave irradiation under solvent free condition. The synthesized heterocycles 4a–o and 6a–o were further confirmed by using different spectroscopic techniques such as NMR and HRMS. The compounds 6a–o was studied for their solvatochromic property with increasing polarity of solvents. The determinations of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) scavenging effect of the scaffolds 6a–o were carried out by UV–Vis spectrometer. In terms of IC50 all the compounds have shown remarkable antioxidant property compared with Ascorbic acid. © 2016 Elsevier B.V.