Functionalized sulfamethoxazole and its metal complex: structural characterization, antibacterial and anticancer study of sulfamethoxazolyl-azo-salicylic acid and its copper(II) complex

Sulfamethoxazolyl-azo-salicylic acid, SMX-N=N-C₆H₃(p-OH)(m-COOH) (1) and its Cu(II) complex, Na₂[Cu(SMX-N=N-C₆H₃(p-O)-(m-COO))₂].4H₂O (2) are structurally characterized by different spectroscopic data. The single crystal X-ray structure of 1 shows inter- and intra-molecular hydrogen bonds and π---π interactions and has constituted 1D chain. The optimized structure of 2 is optimized by theoretical computation. The compounds, 1 and 2, show better antimicrobial activity to S. aureus (Gram-positive bacteria) and E. coli (Gram-negative bacteria) relative to the drug SMX and follow the order SMX < 1 < 2. The IC₅₀ data of S. aureus are 320.2 μg/ml (SMX), 210.1 μg/ml (1), 150.2 μg/ml (2) and that of E. coli are 300.1 μg/ml (SMX), 200.0 μg/ml (1), 147.2 μg/ml (2). The compounds, 1 and 2, also exhibit promising anticancer activity against human breast cancer cells, MDA-MB 468 and the LD₅₀ values are 63.00 (1), 65.00 (2) μM. The electronic and spectral properties have been explained by DFT and TD-DFT data. In silico Molecular Docking is analyzed to determine the most favorable binding site of minimum free energy of the drugs with the active site residues of DHPS (dihydropteroate synthetase).