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

Abstract

The experimental fourier transform infrared (FT-IR) and ultraviolet-visible (UV-Vis) spectra of copper(II) and nickel(II) complexes of the deprotonated tetradentate Schiff base ligand N,N -bis(2-hydroxybenzylidene)-2,2-dimethyl-1,3-propanediamine (H 2 L) are compared with their corresponding theoretical ones. The applied theoretical method is based on the density functional theory and time-dependent density functional theory at the UPBE0/PBE0 levels using Def2-TZVP basis set. The computational optimised geometric parameters of the complexes are in good agreement with their corresponding experimental data. The FT-IR and UV-Vis spectra of the complexes were reproduced on the basis of their optimised structures. The vibrational assignments of some fundamental modes of the complexes are performed. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies are calculated. The analyses of the calculated electronic absorption spectra of the complexes are carried out to elucidate the electronic transitions assignments and their characters. Second-order nonlinear optical property of the complexes is evaluated by the above-mentioned theoretical method that implies much greater values for the complexes in comparison with the corresponding value of urea.

Electronic and magnetic properties of the [Ni(salophen)]: An experimental and DFT study

“…Similar bond lengths were observed in the literature for [M(salophen)] (M = Mn, Ni, Cu, and Zn) and related molecular structures [31] , [32] . For [Zn(salophen)(OH 2 )], the coordination site bond distances calculated at the PBE0/6-311G++(d,p) level are equal to 2.104 and 1.987 Å for M-N 12 and M-O 10 , respectively.…”

“…For [Ni(salophen)] obtained using B3LYP/6-31G(d), these values are 1.860 and 1.842 Å, respectively, which is in agreement with crystal refinement obtained by Lecarme et al [32] , who also studied the electronic structure of [Ni(salophen)]-related structures, focusing on one-electron-oxidized Ni(II) salophen complex and its amino derivatives. Optimized structures obtained for [Cu(salophen)] and [Ni(salophen)] at the PBE0/def-TZVP level reported by Zarei et al [31] showed the bond lengths to be: 1.959 and 1.910 and 1.881 and 1.853 Å for Cu—N 12 , Cu—O 10 , Ni—N 12 , and Ni—O 10 , respectively. Finally, Atakol et al [33] identified the structural positions of [Ni(salophen)]-related molecular structures via crystal refinement using the DRX technique.…”

Study of interaction of metal ions with methylthymol blue by chemometrics and quantum chemical calculations

“…The DFT approaches have widely been used to study different aspects of chemical studies, such as investigating electronic structures and reaction mechanisms of some small molecules 29 , 30 , adsorption properties of surface reactions 31 and reaction mechanism of complicated enzymatic systems 32 . In addition, there is a large number of previous studies that used TD-DFT calculations to predict electronic transitions and to establish a correlation between the experimental and computed wavelengths 33 – 38 . In other words, the reliability of DFT approaches to simulate UV–Visible spectra of organic and organometallic molecules are well documented.…”