Facile Synthesis of 5-Aryl-N-(pyrazin-2-yl)thiophene-2-carboxamides via Suzuki Cross-Coupling Reactions, Their Electronic and Nonlinear Optical Properties through DFT Calculations

Synthesis of 1-(4-Bromobenzoyl)-1,3-dicyclohexylurea and Its Arylation via Readily Available Palladium Catalyst-Their Electronic, Spectroscopic, and Nonlinear Optical Studies via a Computational Approach

In this study, we reported the synthesis of 1-(4-bromobenzoyl)-1,3-dicyclohexylurea by the reaction of DCC (N,N'-dicyclohexylcarbodiimide) with 4-bromobenzoic acid. Subsequently, we further synthesized a new series of 1-(4-arylbenzoyl)-1,3-dicyclohexylurea (5a-g) derivatives using a Suzuki cross-coupling reaction between 1-(4-bromobenzoyl)-1,3-dicyclohexylurea (3) and various aryl/heteroaryl boronic acids (4). Thus, density functional theory (DFT) calculations have been performed to examine the electronic structure of the synthesized compounds (3, 5a-g) and to calculate their spectroscopic data. Moreover, optimized geometries and thermodynamic properties, such as frontier molecular orbitals (HOMO, LUMO), molecular electrostatic potential surfaces, and reactivity descriptors, were also calculated at the PBE0-D3BJ/def2-TZVP/SMD1,4-dioxane level of theory to validate the structures of the synthesized compounds.

Computational Study of Benzothiazole Derivatives for Conformational, Thermodynamic and Spectroscopic Features and Their Potential to Act as Antibacterials

Benzothiazole analogs are very interesting due to their potential activity against several infections. In this research, five benzothiazole derivatives were studied using density functional theory calculations. The optimized geometry, geometrical parameters and vibrational spectra were analyzed. The charge distribution diagrams, such as FMO (HOMO-LUMO), energies of HOMO-LUMO, polarizability, hyperpolarizability, MESP and density of states, were calculated. The computed energies of HOMO and LUMO showed that the transfer of charge occurred within the compound. The effect of the change of substituents on the ring on the value of the HOMO-LUMO energy gap was also observed. It was observed that, in this series, compound 4 with CF3 substituent had the lowest energy gap of HOMO-LUMO, and compound 5 with no substituent had highest HOMO-LUMO energy gap. From the energies of HOMO and LUMO, the reactivity descriptors, such as electron affinity (A), ionization potential (I), chemical softness (σ), chemical hardness (ƞ), electronic chemical potential (μ), electrophilicity index (ω), were calculated. In addition, the 13C and 1H NMR chemical shifts of the molecules were calculated using the gauge-independent atomic orbit (GIAO) method; the shifts were in good agreement with the experimental values. The anti-bacterial potential of compounds 1 to 5 was tested by molecular docking studies toward target proteins 2KAU and 7EL1 from Klebsiella aerogenes and Staphylococcus aureus. Compounds 3 and 1 showed high affinity toward 2KAU and 7EL1, respectively.

Facile Synthesis of Functionalized Phenoxy Quinolines: Antibacterial Activities against ESBL Producing Escherichia coli and MRSA, Docking Studies, and Structural Features Determination through Computational Approach

The synthesis of new 6-Bromoquinolin-4-ol derivatives (3a–3h) by Chan–Lam coupling utilizing different types of solvents (protic, aprotic, and mixed solvents) and bases was studied in the present manuscript. Furthermore, their potential against ESBL producing Escherichia coli (ESBL E. coli) and methicillin-resistant Staphylococcusaureus (MRSA) were investigated. Commercially available 6-bromoquinolin-4-ol (3a) was reacted with different types of aryl boronic acids along with Cu(OAc)₂ via Chan–Lam coupling methodology utilizing the protic and aprotic and mixed solvents. The molecules (3a–3h) exhibited very good yields with methanol, moderate yields with DMF, and low yields with ethanol solvents, while the mixed solvent CH₃OH/H₂O (8:1) gave more excellent results as compared to the other solvents. The in vitro antiseptic values against ESBL E. coli and MRSA were calculated at five different deliberations (10, 20, 30, 40, 50 mg/well) by agar well diffusion method. The molecule 3e depicted highest antibacterial activity while compounds 3b and 3d showed low antibacterial activity. Additionally, MIC and MBC standards were calculated against the established bacteria by broth dilution method. Furthermore, a molecular docking investigation of the derivatives (3a–3h) were performed. Compound (3e) was highly active and depicted the least binding energy of −5.4. Moreover, to investigate the essential structural and physical properties, the density functional theory (DFT) findings of the synthesized molecules were accomplished by using the basic set PBE0-D3BJ/def2-TZVP/SMD water level of the theory. The synthesized compounds showed an energy gap from 4.93 to 5.07 eV.