New lanthanum (III) complexes containing azaphosphor β-diketon and diimine ligands: Synthesis, crystallography, morphology properties, DNA binding, DNA cleavage, and DFT calculation

Two octa-coordinated lanthanum (III) complexes of deprotonated azaphosphor beta- diketon and diimine ligands, [LnL3Q] (L = [Cl2CHC(O)NP(O)(NC6H12)2], Q = Phen (C1) and Bipy (C2)), were synthesized and characterized by elemental analysis, IR, and NMR spectra. X-ray crystallography revealed a distorted tetragonal antiprism LaO6N2 coordination geometry around the lanthanum atom in both compounds. Nano-sized complexes (C<acute accent>1 and C <acute accent> 2 ) were synthesized via a sonochemical process and analyzed using SEM and XRPD. TGA-DTA analysis were performed on complexes in both bulk and nano scales. Redox behavior was also examined by cyclic voltammetry. The interaction between the complexes and calf thymus DNA (ct-DNA) was investigated using UV-Vis spectroscopy, fluorescence titration, viscosity measurements, and gel electrophoresis. C2 and C <acute accent> 2 likely intercalate between DNA base pairs through van der Waals forces and hydrogen bonding, whereas C1 and C <acute accent> 1 interact with DNA via groove binding. Further, result indicated the apparent association constant (Kapp) in the range of 4.53 x 104 M- 1-26.86 x 104 M- 1 with the highest value for nanocomplex C <acute accent> 2 . Fluorescence studies revealed dynamic and static quenching for C1 , while the other compounds followed a static quenching process. Hirshfeld surface analysis and the NCI method were employed to demonstrate how non-covalent interactions influence the crystal packing through intermolecular interactions.