Coordination of Zn(II), Pd(II) and Pt(II) with ligands derived from diformylpyridine and thiosemicarbazide: Synthesis, structural characterization, DNA/BSA binding properties and molecular docking analysis

摘要

Synthesis of three novel inorganic complexes (Zn(II), Pd(II), and Pt(II) - [Zn(H2L)] (NO3)(2), [Pd(L)], and [Pt (L)], respectively) based on 2,6-diformylpyridine-bis-(4-phenyl) thiosemicarbazone (H2L) was obtained under reflux medium, yielded in the range of 67% and 86%. Characterization of each compound was done via X-ray diffraction and spectroscopic methods. Structural analysis revealed the formation of complexes with pentagonal and quadratic bipyramidal geometry. Electronic absorption spectra for the ligand and inorganic complexes exhibited pi -> pi* and n -> pi* transitions in the UV region, however, [Pd(L)] and [Pt(L)] showed other less energetic bands attributed to ligand-to-metal charge transfer (LMCT). The interaction between each compound and two macromolecules: calf-thymus DNA (CT-DNA) and bovine serum albumin (BSA) was conducted by spectroscopic techniques combined to molecular docking calculation. For CT-DNA interaction, [Zn(H2L)] (NO3)2 is the weakest intercalate compound and the increasing order of K-b values follows [Zn(H2L)] (NO3)(2) < H2L < [Pd(L)] approximate to [Pt(L)]. Molecular docking results suggested van der Waals interactions as the main intermolecular force involved in the interaction process between DNA and each derivative. For BSA, experimental results indicated weak (H2L and [Zn(H2L)](NO3)(2)) and moderate ([Pd(L)] and [Pt(L)]) interaction in the ground-state, in the proportion 1: 1 (n similar to 1.0). Molecular docking results suggested Trp-212 containing binding site as the main protein pocket for H2L, [Zn(H2L)] (NO3)(2), [Pd(L)], and [Pt(L)].