Bio-Macromolecular Interaction Studies: Synthesis, Crystal structure of Water-Soluble Manganese(II) Complexes

Abstract A new family of mono-chelated water soluble Mn(II) complexes [Mn(Pyimpy)(H2O)Cl2], 1 and [Mn(Me-Pyimpy)(H2O)Cl2], 2 were synthesized using designed tridentate ligands. These Mn(II) complexes (1 and 2) were analyzed through a variety of spectroscopic, analytical and theoretical studies. Single crystal X-ray diffraction of [[Mn(Pyimpy)(H2O)Cl2], 1 confirm distorted octahedral environment with meridionally oriented ligand Pyimpy. Packing illustration of complex 1 shows weak π-π interaction along with H-bonding, Cl-O and Cl-Hpy connections. The Hirshfeld surface investigation of 1 gave quantitative analysis of different types of intermolecular contact such as Cl···H, N···H, C···H, O···H, Cl···O, H···H and C···C and presented by 2D fingerprint plot. Electrochemical studies afforded metal centered reduction [Mn(II)/Mn(I) couple] with E1/2 value of −1.234 and −1.257 V (for 1 and 2, respectively) versus Ag/AgCl. Interactions of water soluble complexes 1 and 2 towards DNA and protein (BSA) have been illustrated. It was establish through UV–visible and fluorescence studies that both metal complexes (1 and 2) interact with ct-DNA and BSA fluorophore using groove and static interactions, respectively. Further, Forster theory of nonradiation energy transfer implimented to obtained the distance, r (arround 4 nm), between BSA (donor) and manganese complexes (acceptor). In Addition, molecular docking studies confirmed adequate interactions of DNA/ protein with complex 1, using crystallographic parameters.