Synthesis, characterization and molecular docking study of Nitro(4′-(2-pyridyl)-2,2′:6′,2″-terpyridyl) Palladium(II) nitrate

Abstract

The title compound Nitro(4′-(2-pyridyl)-2,2′:6′,2″-terpyridyl) palladium(II) nitrate, 1 consists of a terpyridyl derivative 4′-(2-pyridyl)-2,2′:6′,2″-terpyridyl, (terpy) L bonded to a Pd(II) unit through Pd-N coordinate bond. The complex 1 is characterized by 1H, 13C NMR, H-H COSY, C-H COSY and by single crystal X-ray diffraction technique. The NMR data of complex shows the diamagnetic shielding of the signal due to terpy α-proton. The crystal structure of the compound shows that the fourth coordination site of palladium is occupied by a nitrate ion. The electrical neutrality of the complex is maintained by another nitrate ion present outside of the coordination sphere. The core structure of the terpyridine moiety lies almost co-planar and the substituted pyridine group is slightly twisted with respect to the core structure. The dihedral angle between the substituted pyridine group and the mean plane passing through the core terpyridine unit is found to be approximately 12°. Further analysis of the crystal structure show one molecule of the complex cation 1 is linked to two other molecules (one on either side) by inter molecular π-π stacking interaction and forms a one dimensional π-polymer. Several of these π-polymers engaged in further π-π stacking to form the three dimensional array. The complex 1 shows the ability to bind to B-DNA. Molecular docking studies show that complex 1 binds to the minor grove of B-DNA with an attractive van der Waals energy of −7.48 kcal/mol.