Synthesis of New Nano-Sized Cu (II), Co (II), and Zn (II) Complexes From β,β′-Dihydroxy-Dithioether Derivative: Spectroscopic Characterization, DNA Interactions, in Vitro Cytotoxicity, Cell Cycle Analysis and Quantum Chemical Calculations

Nano-sized β,β′-dihydroxydithioether bivalent metal complexes of Cu (II) (C1), Co (II) (C2), and Zn (II) (C3) were produced and analyzed of the form [M(L)(H₂O)n]·X(H₂O) where M = Cu (II); n = 0; X = 0, M = Co (II); n = 2; X = 3, M = Zn (II); n = 2; X = 2, and H₂L = [2,2′-(ethane-1,2-diylbis (sulfanediyl))-bis(1-phenylethan-1-ol)]. Several characteristic methodologies were employed to evaluate our monometallic complexes. Quantum chemical computations were made using DFT (density functional theory), B3LYP functional and 6-31++G(d,p)/SDD basis set in order to determine optimized structure parameters and frontier molecular orbital parameters. Based on DFT and experimental evidence, the complexes ensured that the square planar geometry has been proposed for complex C1, octahedral for complexes C2 and C3. The SEM, XRD, EDX, and AFM investigations of the bivalent metal complexes revealed that the presence of distinct and prominent diffraction peaks signify their crystalline indicates with nanoscale particle dimensions. The absorption measurements reveal the interaction of the nano-sized complexes with CT-DNA via intercalation, exhibiting an intrinsic binding constant (K_b) of 4.69 × 10⁶–6.03 × 10⁶ M⁻¹. Nano-sized metal (II) complexes show a higher viscous nature than H₂SOSO. The antiproliferative activity of the ligand (H₂SOSO) and complexes (C1 to C3) were evaluated in vitro against human liver cells (HepG2) and normal skin fibroblast cells (FG0). Our flow cytometry data indicate significant levels of apoptosis and cell cycle arresting in liver cancer cell lines.