Copper(II)-photocatalyzed Hydrocarboxylation of Schiff bases with CO 2 : antimicrobial evaluation and in silico studies of Schiff bases and unnatural α-amino acids.

We synthesized and characterized two copper(II) complexes: [CuL2Cl]Cl and [CuL'2Cl]Cl , where L  = 2,2'-bipyridine and L' = 4,4'-dimethyl-2,2'-bipyridine. We evaluated their photocatalytic hydrocarboxylation properties on a series of synthesized Schiff bases ( SBs ): (E)-1-(4-((5-bromo-2-hydroxybenzylidene)amino)phenyl)ethanone ( SB1 ), (E)-N-(4-(dimethylamino)benzylidene)benzo[d]thiazol-2-amine ( SB2 ), (E)-4-Bromo-2-((thiazol-2-ylimino)methyl)phenol ( SB3 ), and (E)-4-((5-bromo-2-hydroxybenzylidene)amino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one ( SB4 ). Under mild photocatalytic reaction conditions (room temperature, 1 atm CO 2 , 30-watt Blue LED light), the derivatives of α-amino acids UAA1-4 were obtained with yields ranging from 5% to 44%. Experimental results demonstrated that [CuL2Cl]Cl exhibited superior photocatalytic efficiency compared to [CuL'2Cl]Cl , attributed to favourable electronic properties. In silico studies revealed strong binding strengths with E. faecalis DHFR (4M7U) for docked Schiff bases ( SB ) and unnatural α-amino acids ( UAAs ). In vitro studies further demonstrated significant antimicrobial and antifungal activity for SB2 , SB3 , and SB4 , while none of the synthesized UAAs exhibited such properties, primarily due to the electronic and binding properties of these molecules.Communicated by Ramaswamy H. Sarma.