New Benzimidazole‐Based Fe (III) and Cr (III) Complexes: Characterization, Bioactivity Screening, and Theoretical Implementations Using DFT and Molecular Docking Analysis

Abstract

Two new Fe (III) and Cr (III) complexes had been synthesized and structurally characterized. The new complexes were based on 2‐methyl‐benzimidazole (MB) and salicylic acid (H2L). Elemental analyses, Fourier transform infrared spectroscopy, UV‐–Vis, mass spectra, conductivity, magnetic, and thermal measurements were used to formulate the compounds structures. The results revealed octahedral geometry for both of Fe (III) and Cr (III) complexes. Structure elucidation of these complexes was also supported by density functional theory (DFT) along with optimized geometrical parameters. Natural bond orbital analysis and molecular electrostatic potential were also investigated. Electronic absorption spectra were theoretically performed using the time‐dependent TD‐DFT/B3LYP in gas phase and acetonitrtile as a solvent. Furthermore, the bio‐mimicking activity as antimicrobial and anti‐inflammatory activity of the understudy compounds was in vitro screened. The results showed that the Fe (III) and Cr (III) complexes exhibited higher pathogenic action than the free ligands. Molecular docking investigation against 3T88 (E. Coli) and 5IKT (Cyclooxygenase‐2) was carried out to provide deep insights into their role in inhibiting the growth of pathogenic microbes.

Synthesis, DFT, Biological and Molecular Docking Analysis of Novel Manganese(II), Iron(III), Cobalt(II), Nickel(II), and Copper(II) Chelate Complexes Ligated by 1-(4-Nitrophenylazo)-2-naphthol

“…Since the HOMO and LUMO orbitals define the molecule’s stability, they also define its susceptibility to attack by nucleophiles and electrophiles [ 28 ]. The difference between E LUMO and E HOMO energy levels (ΔE gap) indicates how reactive a molecule is [ 29 , 30 , 31 , 32 ]. To that end, molecules with smaller ΔE are more receptive to docking (CuL > MnL > NiL > FeL > CoL > HL).…”

“…Colors in the red spectrum represent portions of the surface that are negatively charged (i.e., the most favorable areas are accepting an electrophile). The attraction of the compound’s suitable sites in interactions with electrophiles is represented by a decrease in the compound’s negative charge [ 31 ]. The theoretical map of the MEP diagram for the specified compounds is shown in Figure 4 .…”

“…With the use of the 6-311 (d, p) and LANL2DZ basis sets in conjunction with the hybrid correlation functional (B3LYP) [ 39 , 40 ], for the ligand and its complexes, respectively, geometry optimizations of the subject ligand and its complexes were performed [ 1 , 2 , 3 , 4 ]. Quantum chemical properties were determined by using the values of the lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) energies of the compounds in question, as follows: chemical potential (µ = −χ), electronegativity (χ = (IP + EA)/2), energy gap (ΔE = E LOMO − E HOMO ), chemical hardness (η = (IP − EA)/2), nucleophilicity index (N = 1/ω), softness (σ = ½ η), maximum electronic charge (ΔN max = −μ/η), and electrophilicity index (ω = µ 2 /2 η) where EA and IP, are electron affinity (EA = −E LUMO ) and ionization potential (IP = −E HOMO ) [ 21 , 22 , 28 , 31 ].…”

“…We found the widely used antimicrobial Chloramphenicol effective against bacteria and fungi using the same method. The % Activity Index, defined as (IZ of test compound/IZ of Standard) × 100, was used to compare the anti-microbial efficacy of the identified compounds to that of the reference [ 1 , 2 , 3 , 4 , 22 , 31 ].…”

“…Hydrogen atom addition, receptor type connections, potential energy fixation, active pocket search, and dummy generating are all steps in the receptor preparation process. Docking patterns and interaction parameters were exported to score inhibitory activity using a scoring function (S, kcal/mol) and analyze interaction features [ 22 , 23 , 28 , 31 ].…”