Green synthesis, antioxidant and antibacterial activities of 4-aryl-3,4-dihydropyrimidinones/thiones derivatives of curcumin. Theoretical calculations and mechanism study

3,4-Dihydropyrimidin-2(1H)-one/thione analogs of curcumin were synthesized in good yield by a one-pot multi-component cyclocondensation using curcumin, substituted aromatic aldehydes, and urea/thiourea in less volume of ethanol catalysed by commercial heteropolyacide Keggin type H3PMo12O40 5% mol as a recyclable and nontoxic catalyst under conventional heating and microwave irradiation. All the synthesized curcumin derivatives 4a–n were screened for antioxidant and antimicrobial activity. Biological activity data of the synthesized showed that most of the synthesized compounds exhibited greater antioxidant and antibacterial activity than curcumin. Geometries of synthesized compounds were optimized by using B3LYP method with 6-31G* basis set. Then, DFT based reactivity descriptors such as HOMO, LUMO, chemical hardness, electronegativity, chemical potential were calculated and discussed.