Characterization (XRD/TGA-DSC) and assessment of calf thymus DNA interaction with single-crystalline novel complexes from Schiff base ligands

[Display omitted] •XRD/TGA-DSC reveals single-crystal purity and thermal behaviour.•Insight into the structural architecture of the complexes through XRD analysis.•Complexes exhibit moderate intercalation with CT-DNA (Kb ∼ 104 L/mol).•Complex-DNA binding study indicates groove binding with partial intercalation.•Intercalative and lipophilic properties with potential for medicinal applications. The Schiff base complexes [Zn(H2L)2Cl2] 2/3(CH3OH) 2/3(H2O) (1) and [Cd(H2L)2(NO3)2(CH3OH)2] (2), where H2L is an N-Acylhydrazone ligand, have been investigated mainly using a combinatory approach of single-crystal X-ray diffractometry (XRD), thermogravimetric and differential thermal analysis (TGA-DSC). XRD analysis revealed that both complexes coordinate through the nitrogen atom of the ligand’s pyridine ring. In complex (1), the zinc(II) ion coordinates with two ligands and two chloride ions, forming a distorted tetrahedral geometry. In complex (2), the cadmium(II) ion coordinates with two ligands, two nitrate ions, and two methanol molecules, resulting in an octahedral geometry. The crystalline material’s high purity and precise stoichiometry were crucial for accurate thermoanalytical analysis. Additionally, characterizations were performed using infrared (IR), ultraviolet–visible (UV–vis), molar conductivity, elemental analysis (EA) and nuclear magnetic resonance (NMR) spectroscopy. Biological studies with calf thymus DNA (CT-DNA), using UV–vis spectroscopy, viscosity measurements and ethidium bromide displacement assays indicated intercalative binding of the complexes with DNA. The binding (Kb) and quenching (Ksv) constants (104 L/mol) suggest moderate interaction with CT-DNA. The positive partition coefficients (log P) values in water and 1-octanol suggest a significant preference for the lipid-like organic phase, implying that these complexes can efficiently penetrate biological membranes.