Isatin‐Schiff base copper(II) complexes—A DFT study of the metal‐ligand bonding situation

Abstract

Herein, we report results of calculations based on density functional theory (BP86/TZVP) of a set of isatin-Schiff base copper(II) and related complexes, 1-12, that have shown significant pro-apoptotic activity toward diverse tumor cells. The interaction of the copper(II) cation with different ligands has been investigated at the same level of theory. The strength and character of the Cu(II)-L bonding was characterized by metal-ligand bond lengths, vibrational frequencies, binding energies, ligand deformation energies, and natural population analysis. The metal-ligand bonding situation was also characterized by using two complementary topological approaches, the quantum theory of atoms-in-molecules (QTAIM) and the electron localization function (ELF). The calculated electronic g-tensor and hyperfine coupling constants present significant agreement with the EPR experimental data. The calculated parameters pointed to complex 10 as the most stable among the isatin-Schiff base copper(II) species, in good agreement with experimental data that indicate this complex as the most reactive in the series.

Copper(II) and nickel(II) complexes of tetradentate Schiff base ligand: UV-Vis and FT-IR spectra and DFT calculation of electronic, vibrational and nonlinear optical properties

“…The quantum calculations, in particular density functional theory (DFT), are widely used in coordination chemistry not only to achieve a quantitative description of * Corresponding author. Email: sa_zarei@iausdj.ac.ir, Seyedamirzarei@yahoo.com chemical and physical features of different complexes but also to predict new physical and chemical features [16][17][18][19][20][21]. Rigamonti et al reported the DFT calculation of the copper complexes of some salen-type ligands to confirm the assignments of electronic absorption spectra and evaluate the NLO properties [22].…”

A combined EPR spectroscopy and DFT-based structural interpretation of the antitumor properties of oxindolimine-copper(II) complexes

“…They are corroborated by the corresponding DFT-obtained EPR parameters, that indicate a square planar geometry around the metal for all the compounds except for [Cu(isaepy) 2 ] which shows an octahedral geometry with a z axis longer than the others. Differences between the DFT-obtained EPR parameters explored by Caramori et al 20 and the experimental results may be related to the matrix influence on the g-tensors, which was not taken into account during the simulation.…”

“…Figure 2 shows the DFT-optimized structures evaluated in previous investigations. 20 Two functionals, namely BPW91-35 and BPW91-60, were evaluated to understand the influence of spin density and EPR parameters on the combination of exact exchange in hybrid functionals, as previously studied by Kaupp. 24 BP86 was shown to produce underestimated g || values.…”

“…18 Investigations of their antiproliferative activity toward HeLa cells and interactions with crucial biomolecules have been published elsewhere. 19 Geometry optimizations, harmonic frequencies, and Cu-L bonding analysis in different imine-copper complexes had been performed by density functional theory (DFT) by Caramori et al, 20 using the exchange functional of Becke 21 and the correlation functional of Perdew 22 (PB86) as implemented in the Gaussian03 package. 23 The strategy of uncovering the most important structural and spectroscopic characteristics of such oxindolimine-copper complexes by combining DFT studies and experimental EPR data has allowed further rationalization of their antiproliferative activities against tumor cells.…”

Designing boron and metal complexes for fluoride recognition: a computational perspective

“…The topological analysis of the electron density realized through of the QTAIM method shows the existence of bond critical points (BCPs) between the receptors (1-10) and the anion F -, which point to bonding interactions. 39,40 The main molecular graphs have been organized in the Figure 3, while similar representations have been put in the Figure S3. The ratio between the kinetic energy density, Gb, and the potential energy density, Vb, -Gb/Vb, and the electron density, ρb, in the main BCPs of the complexes (1-10) ….…”