Abstract
•Exploring the new synthetic designs of Sulfonamide metal complexes for combined Antimicrobial, Enzyme inhibitory and anti-oxidant properties.•Structural studies of ligands and metal complexes at M06/6-311+G(d,p) levels to explore their synthetic mode.•NBO, MESP and NPA analysis at WB97XD/6-311+G(d,p) function.•Third order GRP analysis to establish the experimental vs theoretical consequences.
In this report, new sulfonamide based ligands (L1)-(L3) from 4-amino-N-(pyrimidin-2-yl)benzene-1-sulfonamide are synthesized and branded on the basis of their physical, analytical and spectral (1H & 13C-NMR, MS, FT-IR, UV–Vis) grounds. The ligands reacted with the transition metals (VO2+, Fe2+, Co2+, Ni2+, Cu2+ & Zn2+) to synthesize their complexes (1)-(18). Their structure was considered by their elemental, conductance, magnetic, physical, and spectral (UV–Vis, FT-IR & MS) analysis. The geometry optimization of the compounds was achieved at M06/6-311+G(d,p). The natural bond orbital (NBO) analysis with a WB97XD/6-311+G(d,p) function demonstrated that the inter-molecular charges and the hyper conjugation play a significant role in stabilizing the molecular systems. The orbital band gap explained chemical interactions and the phenomena of charge transfer. The lowest band gap of HOMO/LUMO (0.78 eV) is shown for compound (l3), while the highest gap of 1.47 eV is found for ligand (L3). The global parameters of reactivity (GRP) have been investigated with (L2) having higher hardness (2.384 eV) and (17) with higher (2.27 eV) softness (S). The in vitro screening results for their antibacterial activity revealed the compound (5) with the highest activity (31 mm) against Streptococcus aureus while the antifungal activity ranged between 11-28 mm with the compound (12) having the highest one for Aspergillus niger. The enzyme inhibition activity (%) against α-Amylase, Protease, Acetylcholinesterase (AChE) and Butyrylcholinesterase (BChE) with highest (75±0.11; IC50: 66±0.11µL, 73±0.11; IC50: 68±0.10 µL, 75±0.12; IC50: 66±0.11 µL and 71±0.12; IC50: 70±0.08 µL) activity for compounds (16), (18), (17), respectively. The antioxidant action was explored by operating several in vitro assays: scavenging activity against DPPH radical, reducing power against ferric oxidation and total phenols as Gallic acid equivalents. Results indicated that the compound (7) has offered the highest (67.02 ± 0.09) DPPH activity. The results revealed all the compounds to be more biologically active than free ligands. These results also indicated that the meal complexes may be considered for further drug design endeavors.
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