•DFT and molecular docking studies were realized on synthesized novel Chalcone-DIM hybrids and Pirazoline-DIM hybrids compounds.•The title compounds were fully characterized by spectroscopy and spectrometric techniques (FT-IR 1H NMR, 13C NMR and HRMS-DART).•Some compounds showed antibacterial activity against Staphilococcus aureus ATCC6538 strain.•Theoretical studies revealed good π-cation, π-π and hydrogen bonding interactions with both catalytic and allosteric sites with PBP2 enzyme of S. aureus strain. In this research we present the synthesis of a novel series of Pyrazoline-DIM hybrids compounds using microwave irradiation as activation energy, derived from their corresponding parent Chalcone-DIM hybrid, both with potential biological activity and not related to β-lactam antibiotics. The antibacterial activity of these compounds, against Staphylococcus aureus, has been investigated by means of in-vitro radial growth inhibition technique and supported by in-silico DFT methods, as well as molecular docking studies on the allosteric and catalytic sites of Penicillin-Binding Protein 2a. Biological activity seems to be correlated with HOMO location in the molecular structure, the HOMO-LUMO gap, softness and electrophilicity index. Docking studies reveal π-cation interactions as well as hydrogen bonds. These interactions and their frequency suggest that the biological activity of the synthetized molecules can be attributed mainly to interactions with the allosteric site instead of the catalytic one. Display omitted