Dinuclear Phenoxo-Bridged Nickel(II) and Copper(II) Complexes of Phenolate-Based Tripodal Ligand: Theoretical and Experimental Insights

Abstract Three dinuclear complexes of composition [NiII2(L)2][ClO4]2 and [CuII2(L)2(OClO3)2].3H2O have been synthesized using a new tripodal ligand [(2-pyridyl)methyl](2-benzyl)-aminomethyl}-phenol (HL)], in its deprotonated form, providing a N2O donor set. Crystallographic analyses reveal that [CuII2(L)2(OClO3)2].3H2O has a diphenoxo-bridged structure. In [CuII2(L)2(OClO3)2].3H2O, each metal center is MIIN2O3-coordinated with a square-pyramidal environment for each copper(II) center. In this work, the molecular structure, harmonic vibrational frequencies and UV-Vis of [NiII2(L)2]2+ and [CuII2(L)2]2+ has been explored. With the help of density functional theory (DFT)/B3LYP techniques and LANL2DZ as a basis set, the ground-state molecule shape and vibrational frequencies were computed. The basic vibrations were allocated using the VEDA program to compute the potential energy distribution (PED) of the vibrational modes. The band gap energies of the title complexes ([NiII2(L)2]2+ and [CuII2(L)2]2+) are 3.21 eV and 1.59 eV, respectively, according to HOMO-LUMO energies. The maximal absorption wavelength and band gap energy of the title complexes were calculated theoretically using the UV absorption spectra. MEP analysis identifies electrophilic and nucleophilic sites. Hirshfeld surface analysis was used to characterize the 3D intermolecular interactions in ([NiII2(L)2]2+ and [CuII2(L)2]2+) of the crystal surface, whereas fingerprint plots were used to explain the 2D interactions. The biological activity of the complexes was investigated using molecular docking.


Introduction
2][3][4] A relationship between structure and function governs the magnetochemistry of polynuclear complexes of transition metals, as examples of molecular nanomagnets.6][7] Researchers have also observed symmetric and asymmetric magneto-structural correlation of dibridge complexes with -mÀhydroxo, mÀphenoxo or mÀalkoxo dimetallic cores, and are continuing to work on this. 1 Transition dinuclear metal complexes and ligands have long piqued the interest of chemists working in a variety of fields.][10][11] Furthermore, many of the examples having two metal centers collaborate, 12 contributing to a better understanding of oxygen transport in metalloenzymes for industrial catalysis. 13,14Despite the broad scope of the complex, each approach may have its own merit, but it should be noted that the various protocols described above have so far been limited, and so, models of such dinuclear centers have been extensively investigated in terms of their structural and functional design. 12,15n the present work, the coordination properties of the nickel(II) and copper(II) complexes of tripodal pyridine amine phenol ligand, HL with N,N,O-donor atoms possessing pendent arms containing benzylic group, are described (Scheme 1).TD-DFT calculations on complexes [Ni II 2 (L) 2 ] 2þ and [Cu II 2 (L) 2 ] 2þ have been performed in order to grow a better grasp of their electrical, structural, and absorption spectral characteristics.Here we provide a comprehensive connection between experimental and theoretical values of complexes [Ni II 2 (L) 2 ][ClO 4 ] 2 and [Cu II 2 (L) 2 ][ClO 4 ] 2 in this paper.DFT is the best method used for the theoretical study of hybrid materials since it gives a good compromise between calculation time and precision of the results.Therefore, the present study aims is to highlight the structural, Hirshfeld surface and IR spectroscopic (theoretical and experimental).Moreover, electrostatic potential (MEP), frontier molecular orbitals (FMOs) and their energy gaps have been constructed for understanding the electronic properties, nucleophilic and electrophilic site of the considered compounds.In addition, a molecular docking analysis was performed whose purpose is to determine the biological activities of complexes.It is a significant method in molecular modeling applications and drug design.16a,b

General remarks
All reagents and solvents were acquired from commercial sources and used exactly as directed.Solvents were dried/purified prior to use.The ligand HL was synthesized according to the reported procedure. 17heme 1. Ligand of pertinence to this work.

General synthetic procedure for complexes
To the methanolic solution of the ligand (0.100 g, 0.33 mmol), the appropriate metal salt [M(H 2 O) 6 ](ClO 4 ) 2 (M ¼ Ni, Cu; 0.33 mmol) dissolved in dry CH 3 OH was added dropwise.Two equivalent of Et 3 N (0.067 g, 0.66 mmol) was added and the reaction mixture was continued for 2 h.A solid crude precipitate was isolated and dried in vacuo.

Crystallographic studies
Single-crystals of [Cu II 2 (L) 2 (OClO 3 ) 2 ] .3H 2 O of appropriate dimensions were used for data collection.Diffraction intensities were collected on a Bruker D8 Venture diffractometer, with graphitemonochromated Mo-K a (0.71073 Å) radiation at 100(2) K.The results were absorption-corrected.The structures were solved by intrinsic phasing using the ShelXT program, 18 and refined with SHELXL.19aThe OLEX2 software was used as a graphical interface.The positions of the hydrogen atoms were estimated but not refined using ideal geometries.On F2, full-matrix least-squares techniques were used to refine all non-hydrogen atoms with anisotropic thermal characteristics.The CIF validation report has been provided in the end of the Supplementary File (Table 1).

Computational details
Using density functional theory (DFT), a computational quantum mechanical modeling approach, the electronic structure of many-body systems was calculated.All computations in this paper were done with the B3LYP levels from the Gaussian 09 W package 20 programmed with the LANL2DZ basis set function of the density functional theory (DFT).3][24] The frequency assignments were done with excellent accuracy by comparing the results of the GAUSS VIEW 5.0 program with symmetry considerations. 25The bond length and bond angle with molecular geometries were analyzed using a Gaussian output file as a source.The vibrational frequencies were calculated and scaled down by a relevant factor. 26Vibrational energy distribution analysis (VEDA) 4 software and Potential energy distribution (PED) data were used to assign vibrational wavenumbers. 27For determining the potential area, Gaussview 09 software 20 was used to create the highest occupied and lowest unoccupied molecular orbital maps (HOMO-LUMO), band energy gap and molecular electrostatic potential maps.To detect the charge transfer throughout the molecule, researchers produced frontier molecular maps.The Auto Dock 4.2.6 software program was also used to investigate the Molecular Docking (ligand-protein) interaction. 28Crystal Explorer 17.5 was used to create the Hirshfeld molecular surfaces and their related 2 dimensional (2D) plots. 29The TD-DFT computation predicts five transitions in the UV-vis range by using orca 5.0. 30

The complexes and their general characterization
A deprotonated ligand, L(-), offers three kinds of donating atoms: an amine-N, a pyridine-N, and  ST1.Perspective view of copper complex is displayed in Figure 1.In an X-ray crystallographic structure, [Cu II 2 (L) 2 (OClO 3 ) 2 ] appears to be a dimeric complex consisting of Cu(II) monomers arranged around a center of   6 For all the reported structures, the asymmetric part of the complex is shaped like an umbrella.Two related complexes combine to form a dimer, with the O1 atoms acting as coordination bridges.The Cu 2 O 2 cycle is a planar cycle.The dihedral angles between the least-squares plane of the Cu 2 O 2 cycle and the N1-N2-Cu1-O1-O1# fN21A-N22A-Cu2A-O22A-O22A$and N21B-N22B-Cu21-O21B-O21B$g plane are 8.072 (83) f1.817(15) and 4.159 (24) ; for the other molecule in the asymmetric unitg for [Cu 2 L 2 (OClO 3 ) 2 ].

Optimized molecular geometry
In Figure 2(A-C), the optimized structure of the titled complexes is presented, and the complexes have C1 point group symmetry.The B3LYP technique with the LANL2DZ basis set was used to determine the optimal structural characteristics of HL and complexes, such as bond lengths and angles.The experimental data in Table ST1-ST3 was compared to the theoretically calculated bond length and angle values for the titled complexes.However, owing to solid-to-gas phase transitions, a few numbers of values vary in the second decimal digits.The majority of the computed and theoretical values are highly correlated.From the structural data given in Table ST2, it was observed that the calculated Cu1-O3 bond lengths and Cu1-O4 bond lengths were found in the range 1.9682 and 2.011 Å, respectively, and these calculated values were well agreed with the experimental values (exp.1.917 and 2.396 Å) given in the Table ST1.The calculated bond lengths of Cu1-N6 and Cu2-O4 were observed in the range of 2.0951 Å and 1.9682 Å, and experimental values of the same bonds were observed at 2.031 Å and 1.9224 Å. Calculated bond lengths Cu1-N6 (2.0951 Å) and Cu2-N8 (2.095 Å) show higher values than N8-C18 (1.5246 Å) and N8-C19 (1.5391 Å) bond lengths.The maximum value of bond angle was observed between O3-Cu1-O4 and O4-Cu2-N7 as 176.22 and 176.20 .The calculated bond angle between O3-Cu1-O4 was 75.51 (exp.78.93 ), this shows a good accord between the calculated and experimental values (Table ST3).The calculated bond angles between the Cu1-O3-Cu2 and Cu1-O4-Cu2 were the same 104.48 and experimental obtained values (99.88 ) were also same.Some of the bond angles like angles between C15-C11-C25, N6-C13-C21 and N6-C13-H28 show a complete agreement between calculated and experimental values.The calculated bond length and angle values of [Ni 2 (L) 2 ] 2þ have been shown in Table ST2 and ST3 and compared with experimental data.From the values given in Table ST2 it was observed that O1-Ni86 bond lengths and O1-Ni85 bond lengths were found in the range 1.8896 and 1.9242 Å, respectively.The calculated bond lengths of N3-Ni86 and N4-Ni86 were observed in the range of 1.9109 and 1.9587 Å, and experimental values of the same bonds were observed at 1.9445 and 2.0363 Å.The calculated bond angle between O1-Ni86-O2 and O1-Ni86-N4 were 79.02 and 95.61 respectively (Table ST3).The calculated bond angles between N86-O1-N85 and N86-O2-N85 were the same 100.97 .

Vibrational frequency analysis
The non-linear molecule maximum number of potentially active observable basis is 3 N-6, where N is the number of atoms in the complex. 33[Cu 2 (L) 2 ] 2þ has 85 stretching modes of vibration, 84 bending modes of vibration and 83 torsion vibrational modes.Figure 3(A,B) depicts theoretical FT-IR spectra of complex [Cu 2 (L) 2 ] 2þ and [Ni 2 (L) 2 ] 2þ , while Table ST4 lists spectral assignments as well as PED contributions of complex [Cu 2 (L) 2 ] 2þ .Further, the unscaled vibrational wavenumbers has been scaled by a relevant factor 0.961.The VEDA program 27 was used to calculate the potential energy distributions.The complex structure is more stable with C1 symmetry, which can be ascribed to the high percentage of Potential Energy Distribution achieved for most basic modes of vibration.A few important vibrations and their characteristics, such as intensities, are discussed below.

C-C vibrations
Carbon vibrations are attributed to the bands between 1400 and 1650 cm À1 in aromatic and hetero aromatic substances. 35Within the range of 1300 À 1000 cm À1 , ring stretching vibrations (C ¼ C) are expected. 36The theoretical frequencies ascribed to CC stretching vibrations in this work are 1584, 1580, 1568, and 1542 cm À1 .Table ST4 shows that the PED of these vibrations for the titled complex is pure modes.

Ni-O vibrations
The bands appeared at 708 and 92 cm À1 are attributed to Ni-O stretching vibrations with 19 and 11% PED assignments.The other peaks appeared in the IR spectrum of Ni dimer observed at 42 cm À1 attributed to Ni-O-Ni bending vibration.The torsion vibrations appeared at 165, 17 cm À1 with 11 and 28% PED are assigned to Ni-O-Ni-N.The bands for C-N-Ni bending vibrations are appeared at 334, 75, 37, and 20 cm À1 with 11, 10, 13, and 14% PED.The bending vibrations for N-Ni-O appeared at wavenumbers 251, 52, and 20 cm À1 .

Other vibrations
In the low wavenumber range (below 600 cm À1 ) bending and torsion vibrations are expected to occur.Because the number of carbon atoms is higher than other atoms and any vibrational motion in the complex leads in the transmission of vibration to these bonds, as shown in Table ST4, the bands appeared at 424, 114, 58, 48, 20, and 19 cm À1 are attributed to CCNCu torsion vibrations with PED assignments of 13, 12, 22, 12, 29, and 24%.There are two torsion vibrations appeared at 1015 and 406 cm À1 assigned to CCCO vibrations with 10 and 20% PED assignments.OCuNC torsion vibrations are appeared at 203 and 145 cm À1 (mode nos.12 and 11).From Table ST4, there is one torsion vibration obtained for NCuOCu with 12% PED.CCCN torsion vibrations are appeared at 91, 54, and 13 cm À1 (mode nos.8, 6, and 1).

Molecular electrostatic potential (MEP)
MEP calculates the relative polarity of a molecule and uses it to explain reactivity, bonding, residual interaction, polarizability, and the structure-activity relationship in biomolecules and medicines.37a,bMEP also includes cellular, molecular and organismal knowledge. 38MEP was performed at the B3LYP/LANL2DZ level optimized geometry with the Gauss view 5.0 software program to determine the electrophilic and nucleophilic reactive sites of the titled complexes, and the MEP map is shown in

Frontier molecular orbital (FMO) and UV-Vis spectral analysis
In MeCN solution, the UV spectra of [Cu 2 (L) 2 ](ClO 4 ) 2 , and in MeOH solution the UV-Vis spectra of [Ni 2 (L) 2 ](ClO 4 ) 2 , as illustrated in Figure 5(A-D), was measured.Table 2 lists the experimental absorption wavelengths (energies) and calculated electronic values of [Cu 2 (L) 2 ](ClO 4 ) 2 , whereas, the experimental and calculated electronic values of [Ni 2 (L) 2 ](ClO 4 ) 2 given in Table ST5.At 492 nm, the absorption wavelengths are measured in [Cu 2 (L) 2 ](ClO 4 ) 2 and estimated to be 498 nm in MeCN solvent.In case of [Ni 2 (L) 2 ](ClO 4 ) 2 the absorption wavelengths are measured at 689 nm and calculated at 645 nm in MeOH.The electronic structure of [Cu 2 (L) 2 ](ClO 4 ) 2 and [Ni 2 (L) 2 ](ClO 4 ) 2 that was optimized in the singlet state was calculated using the Gaussian 09 W software. 20The HOMO energy is defined by electron donation, whereas the LUMO energy is defined by electron uptake, and the difference between the two defines molecule chemical stability. 40The energy gap between the highest occupied and lowest unoccupied molecular orbitals of the title [Cu 2 (L) 2 ](ClO 4 ) 2 is 1.59 eV, and it is 3.21 eV in [Ni 2 (L) 2 ](ClO 4 ) 2 , as shown in Figure 6(A,B), which is a crucial metric in defining molecular electrical transport characteristics because it is a measure of electron conductivity. 41Aside from band gap energy, there are a number of other significant factors linked with  molecule stability, as shown in Table 3  The application of the electrophilicity index to link toxicological behavior has been proven to be valid. 43The sufficiently high value of the electrophilicity index (65.439)serves as a prelude in investigating the title [Cu 2 (L) 2 ] 2þ biological activity in terms of molecular docking, in which the title [Cu 2 (L) 2 ] 2þ serves as the ligand and is docked to appropriate proteins.The B3LYP technique was used to calculate the hypothetical chemical softness of the drug, which was 0.6281 depending on how it was determined.It is obvious that the target drug is less reactive (0.6281) and nontoxic to the environment as a result of the lower value for chemical softness.

Electron density distribution (EDD) and hole density distribution (HDD)
Density distribution maps for electrons (q ele (r)) and hole (q hole (r)) are typical areas of photoexcited states that are comparable to ground state molecular orbitals.Tian Lu and Cheng Zhong 44a,b demonstrated that the Electron density distribution (EDD) and Hole density distribution (HDD) can be described in terms of the molecular orbital wavefunction (U) and configuration coefficient (w), which correspond to the transition of an electron on electronic excitation from an occupied MO(i) to a virtual MO(l), as shown in Equations ( 1) and ( 2).
i !l i! l j 6 ¼ i !l The aforesaid approach was utilized to compute EDD and HDD maps for the titled [Cu 2 (L) 2 ] 2þ and [Ni 2 (L) 2 ] 2þ in this study.Multiwfn 3.3.4,created by Tian Lu, 44a,b was used to do calculations at the DFT-B3LYP/LANL2DZ level using CPCM in MeCN in [Cu 2 (L) 2 ] 2þ and MeOH in [Ni 2 (L) 2 ] 2þ .In MeOH, electronic structure calculations at the TD-DFT-B3LYP/LANL2DZ level with CPCM predicted one major electronic transition in [Cu 2 (L) 2 ] 2þ depicted in Figure 5(A): the intense absorption band at k max ¼ 971.69 nm (1.27 eV) corresponding to HOMO-2!LUMO, whereas, the strong absorption band at k max ¼ 1341.04 nm (0.92 eV)    4 and 5 show the EDD and HDD Centroid coordinates for [Cu 2 (L) 2 ] 2þ and [Ni 2 (L) 2 ] 2þ , respectively, as well as the calculated configuration coefficients for permissible electrical excitations.

Hirshfeld surface analysis
To visualize the intermolecular interactions in the crystal of [Cu 2 (L) 2 ] 2þ , a Hirshfeld surface (HS) research 45 was carried out using Crystal Explorer 17.5. 28Figure 8 shows the Hirshfeld surfaces of [Cu 2 (L) 2 ] 2þ , including dnorm, shape index, de and di, curvedness and fragment patches.The white surface in the HS plotted over dnorm (Figure 8(A)) shows contacts with distances equal to the sum of the vander Waals radii, whereas the red and blue hues indicate distances shorter (in close touch) or longer (distinct contact), respectively. 46The dnorm value is mapped onto the Hirshfeld  The curvedness varies between À3.5772 and 0.4711 Å.The lowest, maximum and mean values for each 3D surface are shown in Table 6.[Cu 2 (L) 2 ] 2þ , 2-D fingerprint map with the dnorm surface exhibits various interactions on the hirshfeld surface, as seen in Figure 9.The calculated distance from the surface to the closest nucleus inside and outside the surface is 1.7409 and 1.7909 Å, respectively, according to the analysis.Based on the E enrichment ratio, a clear picture emerged of the type and contribution of bonds created in the molecule.According to calculations, H-H formed 43.8 percent of the molecular surface, followed by H-O (18%), C-H (15.3%),H-C (13.2%), and Cu-O (3%), as shown in Table 7.

Molecular docking
Molecular docking is a recent approach in computational science that has resulted in substantial advances in prescription disclosure and planning in the realm of medical science. 48The in silico docking technique investigates the coupling mechanism and inclination of a small particle inside the receptor target protein coupling site.The docked ligands were positioned in ligand receptor constructs based on their coupling affinity.The title [Cu 2 (L) 2 ] 2þ , was docked against four proteins (membrane proteins and transport proteins) including 6Y5A, 2W8G, 6VRH and 5I74, in this work (PDB ids), whereas, the [Ni 2 (L) 2 ] 2þ was also docked with 6Y5A, 6VRH, 2W8G and 7LWD proteins.The behavior of biological interfaces such as 6Y5A, 2W8G, 6VRH, 5I74 and 7LWD from the RCSB Protein Data Bank was evaluated using molecular docking.The docking scores for the tested ligands revealed that all of the produced admixtures had the ability to interact with one or more receptor active site (binding pocket).The [Cu 2 (L) 2 ] 2þ had the best docking score with 6VRH protein, À9.1 kcal/mol and a significant score of À9.0 kcal/mol with 6Y5A protein, followed by À8.3 kcal/mol  POLYCYCLIC AROMATIC COMPOUNDS with 2W8G protein and À6.4 kcal/mol with 5I74 protein (Table 8).[Cu 2 (L) 2 ] 2þ binding site in the active site of 6Y5A, 2W8G, 6VRH and 5I74 interaction 3D was depicted in Figure 10.On the other hand, [Ni 2 (L) 2 ] 2þ had the best docking score with 7LWD protein, À9.9 kcal/mol and a significant score of À8.6 kcal/mol with 6VRH protein, followed by À8.3 kcal/mol with 6Y5A protein and À7.6 kcal/mol with 2W8G protein (Table 9).[Ni 2 (L) 2 ] 2þ binding site in the active site of 7LWD, 6VRH, 6Y5A, and 2W8G interaction 3D was depicted in Figure 11.Allampura et.al., studied antimicrobial property of Cu complex against Staphylococcus aureus and methicillin-resistant Staphylococcus aureus which shows that Cu dimer can also show antimicrobial property. 49

Conclusion
HL, a tridentate Mannich base ligand, stabilizes dicationic dinuclear complexes formed by simple chemical methods using Ni(II), and Cu (II).A synthetic method that produced dicationic complexes of the type f[ML] 2 g 2þ with high purity and yield.All experimental measurements confirm that all the complexes have square-pyramidal geometry.By virtue of its phenolate group, each ligand provides a phenoxo bridge.The successful preparation and systematic investigation of three closely related complexes' properties provides a valuable source of information for understanding their structures and magnetic properties.The goal of this study is to use FTIR and UV-Vis techniques and tools derived from density functional theory to reveal the spectroscopic features of title complexes, such as molecular parameters, frequency assignments and electronic transition.The complexes structures were optimized using the DFT/B3LYP approach using LANL2DZ as the basis set.The electrical characteristics of the complexes were investigated both theoretically and practically using the TD-DFT technique and the UV spectrum.The complexes [Cu 2 (L) 2 ] 2þ and [Ni 2 (L) 2 ] 2þ had their vibrational FT-IR spectra recorded and their vibrational wavenumbers and PED were computed.Most of the basics have extremely minor discrepancies between observed and scaled wavenumber values.The existence of ICT within the complexes is shown by Frontier Molecular Orbitals research, which is further validated by charge transfer interactions owing to excitation.The band gap energies of the title complexes were computed using the HOMO and LUMO energy values and they were found to be 1.59 eV and 3.21 eV, respectively.MEP analysis was used to look into the reactive sites of the title complexes.Intermolecular interactions were investigated using Hirshfeld surface analysis of [Cu 2 (L) 2 ](ClO 4 ) 2 , which comprised dnorm, di, de, shape index, curvature and fragment patches, as well as 2D fingerprint diagrams.

Figure 4 .
Different colors represent the different electrostatic potentials at the surfaces, with red indicating the most negative electrostatic potential areas, blue indicating the most positive electrostatic potential areas, and green indicating near zero potential areas.The order of the electrostatic potential on the origin of color code follows red < orange < yellow < green < blue.39a,b The MEP trace clearly shows the potential locations for electrophilic and nucleophilic attacks in the titled complexes.The color coding for these maps is À7.747e-2 e.s.u (red) to þ7.747e-2 e.s.u (deepest blue) in HL, Whereas, in complex [Cu 2 (L) 2 ] 2þ and [Ni 2 (L) 2 ] 2þ these maps have a color coding in the ranges of À0.205e-2 e.s.u to þ0.205e-2 e.s.u and À0.212e-2 e.s.u to þ0.212e-2 e.s.u.In HL, the negative area of electrostatic potential is shown by the red color distributed over the oxygen atom.Blue color surrounds nitrogen and hydrogen atoms, indicating a positive potential area.These are the visible reactive sites of electrophilic and nucleophilic ligand attacks.The MEP surface's predominant green color indicates that the electrostatic potential is located in the middle of the red and blue regions.There are no such electrophilic sites in [Cu 2 (L) 2 ] 2þ and [Ni 2 (L) 2 ] 2þ , as these complexes lack an electron cloud.As a result, the titled complex anticipated reactive site demonstrates the possibility of intermolecular interactions, making [Cu 2 (L) 2 ] 2þ and [Ni 2 (L) 2 ] 2þ chemically and biologically active.

Figure 7 .
Figure 7. (A) EDD and HDD maps of second excited state of Cu dimer in MeCN.(B) EDD and HDD maps of second excited state of Ni dimer in MeOH.

Figure 5 (
Figure 5(C) corresponding to HOMO-8!LUMO involving a single molecular orbital pair excitation from the occupied to the unoccupied orbital.The calculated EDD map (Figure 7(A) shows a significantly denser isosurface localized on Cu and oxygen atoms, whereas the HDD map shows a denser isosurface on the rings attached to oxygen atoms.Tables 4 and 5 show the EDD and HDD Centroid coordinates for [Cu 2 (L) 2 ] 2þ and [Ni 2 (L) 2 ] 2þ , respectively, as well as the calculated configuration coefficients for permissible electrical excitations.

Figure 9 .
Figure 9. 2D fingerprint plot of different contributions for Cu dimer.
in case of [Cu 2 (L) 2 ](ClO 4 ) 2 and Table ST6 in case of [Ni 2 (L) 2 ](ClO 4 ) 2 .The chemical hardness of [Cu 2 (L) 2 ](ClO 4 )2 , which in this study was 0.7961 eV, confirms its stability.Similarly, electronegativity was determined to be 10.2075, which is a measure of an atom attraction to electrons in a covalent connection.The concept of density functional theory (CDFT) is used to predict a variety of properties, including hardness, electrophilicity index, and reactive sites.The Electrophilicity index 42 is a vital CDFT-based descriptor for studying bio-activities.

Table 4 .
Calculated EDD and HDD centroid coordinates and distances for Cu dimer allowed excited state transitions in MeOH.

Table 5 .
Calculated EDD and HDD centroid coordinates and distances for Ni dimer allowed excited state transitions in MeOH.

Table 6 .
Surface property information in Hirshfeld for Cu dimer.

Table 7 .
Finger print percentage of the total surface area for closed contact between atoms inside and outside the surface for Cu dimer.

Table 8 .
Molecular docking of Cu dimer with centromere-related protein inhibitor protein targets.