Synthesis, Structural Characterization, Hirshfeld Surface Analysis, and Antibacterial Study of Pd(II) and Ni(II) Schiff Base Complexes Derived from Aliphatic Diamine

Abstract

A Schiff base bearing two methyl substituents, namely, 6,6′-((1E,1′E)-((2,2-dimethylpropane-1,3-diyl) bis(azanylylidene)) bis(methanylylidene)) bis(2-methylphenol) [H2AD1Me] was synthesized and characterized through physicochemical and spectroscopic analyses. Then, the Schiff base was complexed with Pd(II) and Ni(II) to form [Pd(AD1Me)] and [Ni(AD1Me)], respectively. Both metal complexes were successfully obtained and characterized through several analyses, viz., melting point, elemental analysis, molar conductivity, magnetic susceptibility, FTIR, 1H NMR, UV–vis, and single crystal X-ray diffraction. A quantitative analysis of the intermolecular interactions in the crystal structures has been performed using Hirshfeld surface analysis. Both metal complexes were crystallized in a monoclinic crystal system with the space group of P21/c. Additionally, the deprotonated phenolic oxygen atom (O1/O2) and azomethine nitrogen atom (N1/N2) of the ligand chelate the Pd(II) and Ni(II) ions, forming a slightly distorted square-planar complex containing three six-membered rings encircling the metal core with dsp2 hybridization. The shift of ν(CN) to a higher frequency in FTIR by 26–28 cm–1 indicated that the complexation to Pd(II) and Ni(II) through the azomethine N was established. It was further supported through the shifting of the azomethine proton signal to higher or lower chemical shifts with Δδ = 0.43–1.15 ppm in 1H NMR. In addition, the shifting of the n−π*(CN) band in UV–vis spectra with Δλ = 24–40 nm indicated the involvement of azomethine nitrogen in the complexation. All the compounds showed no significant antibacterial activity against three bacterial strains, namely, Staphylococcus aureus subsp. aureus Rosenbach (ATCC 6538), Streptococcus mutans Clarke (ATCC 700,610), and Proteus vulgaris (ATCC 6380), as the percent growth inhibition calculated was less than 90%.

Synthesis of a Family of Pd(II) Complexes Using Pyridyl-Ketone Ligands: Crystal Structure, Thermal, Physicochemical, XRD/HSA, Docking, and Heck Reaction Application

“…The HSA computational analysis was carried out via Crystal Explorer 3.1 . The X-ray structure determination of complex-3 was conducted by using a Bruker SMART diffractometer with graphite monochromate Mo Kα radiation (λ = 0.71069 Å).…”

“…The HSA computational analysis was carried out via Crystal Explorer 3.1. 23 The X-ray structure determination of complex-3 was conducted by using a Bruker SMART diffractometer with graphite monochromate Mo Kα radiation (λ = 0.71069 Å). The P 2 1 / c space group structure was determined using a direct technique and enhanced using the SHELXL-97 computer package using full matrix least-squares analysis.…”

Synthesis, Characterization of Two New Schiff Base and Their PdII Complexes and Investigation of Palladium Catalyzed Cross-Coupling Reactions

“…-CH), 2.64, 2.63 (q, 2H, CH 2 ), 2.39 (s, 3H, -CH 3 ), 1.22 (t, 3H, -CH 2 CH 3 ). 13 C-NMR (100 MHz, CDCl 3 ) δ, ppm: 161.23 (C7), 160.99 (C2), 156.59 (C8), 139.58-107.56 (C1-C6, C9-C11, C13), 20.88 (C17), 14.37-13.36 (C16, C18). -CH), 2.67 (q, 2H, CH 2 ), 2.41 (s, 3H, -CH 3 ), 1.23 (t, 3H, -CH 2 CH 3 ).…”