NMR Chemical Shift Values Research Articles

1H, 13C, 15N NMR, and DFT Studies on Complex Formation of Zinc(II) Ion with Ethylenediamine in Ionic Liquid [C2mIm][TFSA

In bis(trifluoromethylsulfonyl)amide (TFSA-)-based ionic liquid (IL), 1-ethyl-3-methylimidazolium TFSA- ([C2mIm][TFSA]), the complex formation equilibria of zinc(II) ion (Zn2+) with ethylenediamine (EN) have been investigated. An EN molecule may coordinate with Zn2+ as a bidentate ligand. First, the formation of Zn2+-EN complexes in [C2mIm][TFSA] was confirmed from the difference of 1H and 13C NMR chemical shift values of EN molecules between [C2mIm][TFSA]-EN binary solvents and the 0.1 mol dm-3 Zn(TFSA)2/[C2mIm][TFSA]-EN solutions as a function of EN mole fraction xEN. Second, the stability constants of Zn2+-EN complexes formed in the IL were determined from the concentration ratio [EN]/[Zn2+] dependence of 15N NMR chemical shift values of the TFSA- N atom in the Zn2+/IL-EN solutions. In the IL, mono-, bis-, and tris-EN complexes are successively formed by 1:1 replacement of TFSA- anions coordinated with Zn2+ by EN molecules with increasing EN content. Third, 1H and 13C NMR measurements with the help of density functional theory (DFT) calculations were made on [C2mIm][TFSA]-EN binary solvents as a function of xEN to clarify key interactions to the mechanism of the complex formation. Fourth, the stability constants of Zn2+-EN complexes in the IL were compared with those in aqueous solutions. It was suggested that the hydrogen bonding of the EN molecule with the imidazolium ring H atoms and the TFSA- O atoms reduces the stability of the mono-EN complex in the IL. In contrast, the intracomplex hydrogen bonds between EN and TFSA- in the first coordination shell contribute to the higher stability of the bis-EN complex in the IL than that in aqueous solutions. The difference in the stability constants between the tris-EN complexes and hexaacetonitrile complexes, where acetonitrile (AN) molecules act as monodentate ligands, was interpreted in terms of the higher electron donicity of EN. Finally, to verify the present evaluation, the experimental 13C NMR chemical shift values of EN molecules in the solutions were compared with the theoretical values calculated by DFT using the stability constants determined.

Synthesis, QTAIM, anticancer activity analysis of pyrrole-imidazole/benzimidazole derivatives and investigation of their reactivity properties using DFT calculations and molecular docking

As part of our ongoing investigation into pyrrole derivatives, we here present the synthesis, spectroscopic characterization, QTAIM, reactivity, anticancer activity, and comparative experimental and computational analysis of pyrrole-imidazole ((3l), (3p)) and benzimidazole derivatives ((3h), (3i), (3j), (3k), (3m), (3n), (3o)). All synthesized compounds (3h-3p) have been well characterized by spectroscopic techniques (FT-IR, 1H and 13C NMR, Mass spectrometry). The experimental 1H and 13C NMR chemical shift values of synthesized pyrrole-imidazole (3l, 3p) and benzimidazole (3h-3o) derivatives have been well corroborated with computed chemical shifts. The vibrational analysis for four derivatives of pyrrole-benzimidazole (3m), (3n), (3o), and pyrrole-imidazole (3p) has the suitability for dimer formation in solid state by intermolecular heteronuclear hydrogen bonding (N–H···O) and the interaction energy of dimers are calculated to be 10.88, 11.70, 9.89 and 10.72 kcal/mol, using DFT. After basis-set superposition error (BSSE) correction, the interaction energies of dimers were found to be 11.12, 12.11, 10.13, and 11.52 kcal/mol. Estimated intermolecular H-bond in (3m-3n) compounds were found to be -13.38, -12.86, -11.02, and -11.28 kJ/mol using QTAIM. All the synthetic pyrrole-imidazole (3l, 3p) and benzimidazole (3h-3o) derivatives exhibit strong antileukemia activity in vitro against the proliferative cell line L1210 leukemia cells. A dataset of investigated compounds was subjected for molecular modelling simulation against three distinct proteins (SYK, PI3K, and BTK), which was found to be highly implicated in the favourable interaction between the compounds and their target proteins in every instance. The synthesized pyrrole-imidazole (3l, 3p) and benzimidazole (3h-3o) derivatives shown favourable interactions with their target proteins, with high activity and binding free energy values falling between 15.22 and 13.43 and -7.4 and -9.8 kcal/mol, respectively. The structure of pyrrole-imidazole (3l, 3p) and benzimidazole (3h-3o) derivatives is thoroughly examined, and several parameters are proposed here to improve their anticancer activity.

Impact of solvents on electronic transition, molecular structure, and spectroscopy analysis of newly synthesized 3-methoxy-5-(1-phenyl-3-p-tolyl-1H-pyrazol-4-yl)-4H-1,2, 4-triazole- rheumatoid arthritis agent

Theoretical DFT calculation and Experimental analysis, such as FTIR and NMR were done on the title compound to anticipate its structural properties, frequency analysis and electronic parameters. The title compound was synthesized using ultrasound radiation. Through optimization, structural properties were found and prominent bond variables of the title compound were highlighted. Frequency analyses for all the normal modes were analyzed and compared with experimental FTIR values. MEP and ESP explain the active region of the title compound. Frontier molecular orbital pictures the electron occupations through HOMO and LUMO orbitals. Benzonitrile, benzyl alcohol, DMF, DMSO, ethanol, Trifluoroethanol, chloroform, methanol, water and gas are the solvents used in UV analysis to find out the solvation effects of the chosen compound. NMR Chemical shift values were predicted using both theoretical and experimental techniques. Optical property was also investigated and the results are compared with prototype substance. Surface properties was analyzed using Multiwfn and VMD softwares. In addition, Drug like properties reveals that title compound does not have any violation against Lipinski's rule of five. Molecular docking was also carried out.

A comparative DFT study of monosubstituted silabenzene and benzene structures: Effects of Si atom incorporation in benzene ring

In the present study, monosubstituted structures with 16 substitutions in the ortho, meta, and para positions of silabenzene have been comprehensively compared with similar structures in benzene. This study aimed to investigate the effect of Si atom incorporation in the benzene ring. This comparison investigated the chemical properties, including structural geometries of molecules, molecular orbitals and reactivity, ring aromaticity, and excitation energy of each monosubstituted silabenzene and benzene structure. The density functional theory (DFT) at the B3LYP/6–311G++(d,p) level of theory was used to perform all relevant calculations. In addition to changes in ring geometry values and electron donating, the results showed that the Si atom incorporation in benzene ring and its monosubstituted derivatives in different positions caused a significant decrease in LUMO, chemical hardness, ring aromaticity, excitation energy, and a significant increase in HOMO, electrophilicity, nucleophilicity, and NMR chemical shift values. Among the positions of the substituents concerning the Si atom in the ring, the ortho and para positions exhibited the most optimal values. In contrast, the meta position displayed different values compared to the ortho and para positions. This difference is attributed to the electron-withdrawing effects of the substituents. Also, among substitutions, electron-donating substitutions especially -NH2 compared to electron-withdrawing substitutions especially -NO2 decreased HOMO, electrophilicity, excitation energy, and increased LUMO, chemical hardness, nucleophilicity, and ring aromaticity.

Imidazole Based Novel Schiff Base: Synthesis, Characterization, Quantum Chemical Calculations, In Silico Investigation of ADMEt Properties and Molecular Docking Simulations against VEGFR2 Protein

The potential drug candidate novel Schiff base, 2-(((3-(4-methyl-1H-imidazol-1-yl)-5-(trifluoromethyl)phenyl)imino)methyl)phenol (MITPIM) was synthesized by the reaction of salicylaldehyde and 3-(4-methyl-1H-imidazol-1-yl)-5-(trifluoromethyl)aniline which is the precursor of the nilotinib molecule used in the cancer treatment. It was characterizated by using spectroscopic techniques such as 1H-NMR, 13C-NMR, 19F-NMR, FT-IR and UV-Vis. DFT computational technique was used for further investigation. DFT/B3LYP method and the 6-311G(d,p) basis set were used to determine optimized geometry. Then by using optimized geometry and DFT approach three-dimensional molecular electrostatic potential (MEP), vibration frequencies, NMR chemical shift values, HOMOs-LUMOs and molecular orbital energies were calculated. It was observed that the experimental and theoretical datas were in good agreement. The ADME and toxicity properties were investigated by using online servers. According to the results, it was concluded that the MITPIM has low toxicity and high oral bioavailability. Molecular docking simulations of the MITPIM with VEGFR2 protein (PDB ID: 2XIR) were investigated. According to molecular docking studies, the binding energy of the complex formed by the MITPIM with VEGFR2 protein (PDB ID: 2XIR) was −9.34 kcal/mol and the value was close to nilotinib’s binding score which was -9.69 kcal/mol. Molecular docking and ADMEt results shown that the newly synthesized MITPIM has the potential to be drug.

5‐Bromosalicylaldehyde: Theoretical, Experimental and Spectroscopic (FT‐IR, Raman, H1 and C13‐NMR, UV‐Vis) Studies and Their Photovoltaic Parameters

AbstractThis study aims to identify a 5‐bromosalicylaldehyde (5BSA) and assess its performance for application in organic solar cells. In the current work, the 5BSA was investigated using various techniques such as FT‐IR, Raman, NMR, and UV‐Vis spectroscopy to characterize the title molecule. The possible conformers of the 5BSA were studied using the MMFF methodology in Spartan software. The geometry optimization of modifications for each conformation was computed using the DFT approach for the B3LYP/6‐311++G(d,p) functional. The energy and dipole moment of most stable form were determined −1879057.42 kcal/mol and 1.455 Debye, respectively. The FT‐IR and Raman vibrational frequencies, the H1 and C13 NMR chemical shift values (in vacuum and in DMSO‐d6), the UV spectrum calculations (both in vacuum and in the solvent ethanol), the HOMO‐LUMO energy, and the map of MEP. Meanwhile, by considering the properties of organic photovoltaic cells, the open‐circuit voltage (VOC), hole reorganization energy (λh) and electron reorganization energy (λe), light‐harvesting efficiency (LHE), total reorganization energy (λtotal), the short‐circuit current density (Jsc), the driving force (ΔGinject), binding energy (Eb) were also computed for the title compound. In addition, transition density matrix (TDM) and density of states (DOS) analyses were conducted for the 5BSA molecule.

Solvent effects on spectroscopic, electronic, and topological analyses, Hirshfeld surface, ADME, and molecular docking studies on antiviral pyridine carboxamide derivatives

A theoretical study of three pyridine carboxamide derivatives in conjunction with the Density Functional Theory (DFT) approach at the 6-311+G(d,p) basis set is presented along with X-ray results. The pyridine carboxamide derivatives were analyzed with the help of FT-IR, UV–Vis, 1H and 13C NMR investigation. The spectral characterizations were made by vibrational energy distribution analysis (VEDA4), which helps to assign vibrational frequencies to specific molecular vibrations. A comparative analysis of computed 1H and 13C NMR chemical shift values with experimental chemical shifts for the pyridine carboxamide compounds by applying the gauge-including atomic orbitals method in chloroform and acetone solvents was carried out. UV–Vis spectroscopy and electronic transitions were conducted on both chloroform and acetone solvents through the assistance of the TD-DFT methodology. Hirshfeld Surface analysis was employed to analyze the intermolecular hydrogen bonds of the type N-H⋯N to the crystal packing. The chemical properties of frontier molecular orbital and global reactivity descriptors were analyzed for the different solvents such as chloroform and acetone. The Fukui functions were used to identify reactive sites in a molecule, including those susceptible to nucleophilic and electrophilic outbreaks. The weak interactions were analyzed using reduced density gradient (RDG) analysis, a computational method used to study noncovalent interactions, including hydrogen bonding. The Absorption, Distribution, Metabolism, and Excretion (ADME) attributes of the studied compounds have been evaluated for drug discovery initiatives. Molecular docking studies with antiviral SARS-CoV-2 Mpro and Omicron variant containing the Q493R mutation proteins of three pyridine carboxamide derivatives (L3–L5) have been performed, and L5 has maximum binding energy values of −7.13 kcal/mol for 6LU7.

Quantum Chemical and Biological Properties of Coumarin Derivative Compound

This work presents the characterization of 8-t-buthyl-4-methyl-2H- chromen 2-one by quantum chemical calculations and spectral techniques. The molecular geometry, vibrational frequencies and gauge including atomic orbital (GIAO) 1H and 13C NMR chemical shift values of title compound in the ground state have been calculated using the density functional method (B3LYP) with the 6-31G(d) basis set. The theoretical vibrational frequencies and chemical shift values show good agreement with experimental values. In addition, DFT calculations of molecular electrostatic potentials and frontier molecular orbitals of the title were carried out at the B3LYP/6-31G(d) level of theory. The title compound was screened for antibacterial, antifungal and antioxidant activities.

A Novel Anthraquinone-Based Azo Compound: Synthesis, Quantum Chemical Calculations and Investigation of ADMET Properties

This study involved the synthesis of the potentially drug candidate 2-((9,10-dioxo-9,10-dihydroanthracen-2-yl)diazenyl)-5-hydroxybenzoic acid (DHA), the elucidation of its structure using spectroscopic techniques and the determination of the compound's lowest energy structure using the DFT/B3LYP method and the 6-311G(d,p) basis set. The compound's vibration frequencies and NMR chemical shift values were then determined using optimized geometry. The three-dimensional molecular electrostatic potential (MEP) map of the compound and the HOMOs-LUMOs and molecular orbital energies were examined using the DFT approach. The compound's ADMET properties were then determined, and its potential for usage as a drug was assessed. Additionally, the predicted toxicity class and LD50 value for the DHA were established. The outcomes demonstrated that by having ADMET properties, this newly synthesized compound has the potential to be a drug.

NMR-Metabolomic Profiling and Genome Mining Drive the Discovery of Cyclic Decapeptides from a Marine Streptomyces.

The integration of NMR-metabolomic and genomic analyses can provide enhanced identification of structural properties as well as key biosynthetic information, thus achieving the targeted discovery of new natural products. For this purpose, NMR-based metabolomic profiling of the marine-derived Streptomyces sp. S063 (CGMCC 14582) was performed, by which N-methylated peptides possessing unusual negative 1H NMR chemical shift values were tracked. Meanwhile, genome mining of this strain revealed the presence of an unknown NRPS gene cluster (len) with piperazic-acid-encoding genes (lenE and lenF). Under the guidance of the combined information, two cyclic decapeptides, lenziamides D1 (1) and B1 (2), were isolated from Streptomyces sp. S063, which contains piperazic acids with negative 1H NMR values. The structures of 1 and 2 were determined by extensive spectroscopic analysis combined with Marfey's method and ECD calculations. Furthermore, we provided a detailed model of lenziamide (1 and 2) biosynthesis in Streptomyces sp. S063. In the cytotoxicity evaluation, 1 and 2 showed moderate growth inhibition against the human cancer cells HEL, H1975, H1299, and drug-resistant A549-taxol with IC50 values of 8-24 μM.

Shielding Effects of Aromatic (Indole) Ring for Structural Analysis.

This review provides a critical analysis of shielding effects induced by an aromatic (indole) ring of small molecules mainly including three members of naturally occurring secondary metabolites asterric acid analogs, diketopiperazines (DKPs) possessing an aromatic or an indole ring, and rubrolides. Empirical rules about the shielding effects induced by an aromatic (indole) ring are classified, based on which some 1H NMR chemical shift values in the A-ring and structures of asterric acid analogs are revised, and the relative configurations of some DKPs possessing an indole ring are also assigned or revised. The empirical rules could provide an efficient and convenient method for NMR data analysis and configuration determination for the three members of small molecules mentioned above.

Some morpholine tethered novel aurones: Design, synthesis, biological, kinetic and molecular docking studies

Enzymes are the biological macromolecules that have emerged as an important drug target as their upregulation/imbalance leads to various pathological conditions, such as inflammation, parasitic infection, Alzheimer’s, cancer, and many others. Here, we designed and synthesized some morpholine tethered novel aurones and evaluated them as potential inhibitors for CTSB, α-amylase, lipase and activator for trypsin. All the newly synthesized compounds were fully characterized by various spectroscopic techniques (1H NMR, 13C NMR, HRMS) and the Z-configuration to them was assigned based on single crystal XRD data and 1H NMR chemical shift values. Further, the hybrids were evaluated for their intracellular (cathepsin B) and extracellular (trypsin, lipase, amylase) enzyme inhibition potencies. The in-vitro inhibition screening against cathepsin B revealed that most of the synthesized compounds are good competitive inhibitors (% inhibition = 22.91–75.04), with 6q (% inhibition = 75.04) and 6r (% inhibition = 71.13) as the eminent inhibitors of the series. At the same time, they exhibited weak to moderate inhibition towards amylase (% inhibition = 7.22–22.48) and lipase (% inhibition = 16.29–54.83). A significant trypsin activation (% activation = 107.42–196.47) was observed even at the micromolar concentration of the compounds. Furthermore, the drug-modeling studies showed a good correlation between the in-vitro experimental results and the calculated binding affinity of the screened compounds with all the tested enzymes. These findings are expected to provide a new lead in drug development for different pathological disorders wherever these enzymes are involved.

Assessment of the Commercially Available Chemical Space for Using in the 19F NMR FAXS Method: a Enamine Ltd. Case

Aim. To analyze commercially available fluorine containing compounds for the possibility of their use in the 19F NMR FAXS method.Materials and methods. The selection of fluorine-containing fragments for the study was performed using 3.9 million instock screening compounds and 248,000 in-stock building-blocks from Enamine Ltd library. The selection and classification of the compounds was carried out using the DataWarrior and KNIME software. The Fluorinated Fragments library of Enamine Ltd. containing 6377 compounds, was also analyzed. To analyze the abovementioned sets of substances, the multistep workflows specially designed were used.Results and discussion. As a result of applying the workflow developed to the compound sets (both screening compounds and building blocks), 13 800 compounds were selected and further classified according to the presence of one out of 12 fluorine-containing groups. The Fluorinated Fragments library was also subjected to a similar workflow. For the latter, 8 out of 12 fluorine-containing groups were identified. Additionally, experimental 19F NMR chemical shift values for Fluorinated Fragments library compounds spectra were analyzed. It has been found that some structural classes have areas of chemical shifts intersection. On the other hand, the ranges from –40 to –60 ppm and beyond –160 ppm are free from any group of compounds from the library analyzed.Conclusions. The analysis has shown that commercially available fluorine-containing fragments do not satisfy the needs of the 19F NMR FAXS method, and further expansion of the chemical space of fluorine-containing compounds by increasing their diversity is required.

Linking quinoline ring to 5-nitrofuran moiety via sulfonyl hydrazone bridge: Synthesis, structural characterization, DFT studies, and evaluation of antibacterial and antifungal activity

In the present work, we report the synthesis, structural characterization, and computational studies of (E)-N'-((5-nitrofuran-2-yl)methylene)quinoline-8-sulfonohydrazide (QNF) as a potential antimicrobial drug candidate. To design the target molecule, we utilized a molecular hybridization technique that connects two antimicrobial pharmacophores (quinoline and 5-nitrofuran rings) with a sulfonyl hydrazone moiety. QNF was synthesized by the condensation of quinoline-8-sulfonohydrazide with 5-nitrofuran-2-carbaldehyde, and characterized by various spectral techniques including single-crystal X-ray crystallography. QNF was extensively evaluated for its antibacterial and antifungal activity. The inhibition capacity of QNF on Candida albicans filamentation and biofilm formation was further investigated. Biofilm inhibition of QNF against C. albicans was supported by molecular docking studies in the binding site of agglutinin-like sequence 3 (Als3). Drug-like profile of QNF was confirmed by in silico calculation of its significant physicochemical properties. Additionally, the optimized geometrical structure, natural bond orbital calculations, frontier molecular orbital and molecular electrostatic potential analysis of QNF were carried out using the density functional theory method at the B3LYP with 6–31+G(d,p) basis set. The predictions of 1H and 13C NMR chemical shift values were performed using the gauge-independent atomic orbital method. Structural parameters and NMR values obtained experimentally were compared with the calculated values.

Nucleophilic reactions with the novel 7-(chromon-3-yl)quinolino [3′,4′:5,6] pyrano[3,2-c]quinoline: Synthesis, biological and computational studies

Condensation reaction of 3-formylchromone (1) with 1-ethyl-4-hydroxyquinolin-2(1H)-one (2) in glacial acetic acid afforded the condensation product 4; in 1:2 molar ratio. Compound 4 was used as precursor for construction of some propenones linked pentacyclic quinolinopyranoquinoline. Ring opening of chromone moiety in compound 4 was achieved via reactions with a diversity of primary amines leading to propenone derivatives 5–7 and 11–13 in good yields (62–73%). All propanone derivatives exist in the E-configuration as deduced from their 1H NMR spectra. DFT/B3LYP functional was used with 6–311+G(d,p) basis sets for all theoretical calculations. Based on optimized geometry, the chemical potential (Pi), electronegativity (χ), hardness (η) and electrophilicity index (ω) are some of the global reactivity descriptors that were computed to predict the chemical reactivity of the studied compounds; where compound 13 has the highest softness and electrophilicity index (ω). Moreover, to determine the relative stability of compounds 1–4, the thermodynamic parameters such as enthalpy and free energies of the reactions were computed; where compound 4 has the lowest free energy of reaction (-439.61 kcal/mol), so its formation is spontaneous. By utilizing molecular electrostatic potential (MEP) and local-based descriptors in the form of condensed Fukui functions of the starting compound 4, the susceptible sites for electrophilic and nucleophilic attack were investigated. For compound 4, fk+ and Δfk values are more positive at C9 and C7 than other sites and these sites have more electrophilic characters. Therefore, nucleophilic attacks began at C9. On the other hand, the GIAO approximation was used to compute the 1H and 13C NMR chemical shift values in the ground state, of the present compounds, where a good agreement was observed between experimental and theoretical chemical shift results. Further, the calculated first hyperpolarizability of prepared compounds are found to be greater than that of urea. So, these compounds are ideal candidates for non-linear optical applications. The synthesized compounds were screened for their antimicrobial and anticancer activities showing variable inhibitory action. Compounds 5, 7 and 13 were more effective antimicrobial candidates against all tested microorganisms, while compound 13 was the most active against HepG-2 cell lines. Furthermore, a quantitative structure–activity relationship (QSAR) (relationship between DFT calculated descriptors and biological activities pIC50) model was built by applying multiple linear regression (MLR) on the synthesized compounds as anticancer agents. Moreover, Lipinski's rule of five indicates no problems with oral bioavailability of the prepared compounds.

Spectroscopic investigations, quantum chemical, drug likeness and molecular docking studies of methyl 1-methyl-4-nitro-pyrrole-2-carboxylate: A novel ovarian cancer drug

Density functional theory (DFT) calculation was used to analyse the structural and vibrational properties of Methyl 1-Methyl-4-nitro-pyrrole-2-carboxylate (MMNPC) using the cc-pVTZ basis set. The potential energy surface scan and the most stable molecular structure were optimized using Gaussian 09 program. A potential energy distribution calculation was used to calculate and assign vibrational frequencies using the VEDA 4.0 program package. The Frontier Molecular Orbitals (FMOs) were analysed to determine their related molecular properties. Ab initio density functional theory (B3LYP/cc-pVTZ) method with basis set was used to calculate 13C NMR chemical shift values of MMNPC in the ground state. Fukui function and molecular electrostatic potential (MEP) analysis confirmed the bioactivity of the MMNPC molecule. The charge delocalization and stability of the title compound were studied using natural bond orbital analysis. All experimental spectral values from FT-IR, FT-Raman, UV–VIS, and 13C NMR are in good agreement with the value calculated by the DFT. Molecular docking analysis was carried out to find the MMNPC compound that can be used as a potential drug development candidate for ovarian cancer.

Chemical reactivity of 3-substituted-6,8-dimethylchromones towards 1H-benzimidazol-2-ylacetonitrile and 5-amino-2,4-dihydro-3H-pyrazol-3-one: Spectroscopic, theoretical and in silico ADME studies

The reactivity of 1H-benzimidazol-2-ylacetonitrile and 5-amino-2,4-dihydro-3H-pyrazol-3-one, as nucleophilic reagents, was examined towards some 3-substituted-6,8-dimethylchromones 2a-d. A diversity of novel pyrido[1,2-a]benzimidazoles, chromeno[2,3-b]pyridines, pyrazolo[3,4-b]pyridines and chromenopyrazolopyridines was efficiently synthesized through different chemical transformations; depending on the functional group present at C-3 position of the chromone moiety. With B3LYP/6–311 G(d,p) basis set in the ground state, density functional theory (DFT) is used to determine the molecular geometry of synthesized compounds. The reactivity of the current compounds was studied by global reactivity descriptors at the same level of theory. In order to forecast the reactive locations on the starting substrates 2a-d for nucleophilic and electrophilic attacks, Fukui functions (local reactivity descriptors) were computed at the same level of theory. On the other hand, molecular electrostatic potential (MEP) surface maps were used to identify the nucleophilic and electrophilic sites. Moreover, 1H and 13C NMR chemical shift values in the ground state was calculated using the Gauge-Including Atomic Orbital (GIAO) technique, and the predicted values were compared with the experimental results. To interpret the nonlinear optical (NLO) property of the synthesized compounds, the dipole moment, polarizability, and first hyperpolarizability values have been measured (in the range β = 0.38 × 1030 - 3.28 × 10−30 esu). First hyperpolarizabilities of the investigated compounds indicate promising candidates for nonlinear optical applications. Also, using web-based platforms, in silico ADME calculations were performed.

Synthesis, characterization, DFT, non-covalent interactions and antioxidant activity of N2O2-type template complexes of Zn(II)-derived from 5-ethoxy-2-hydroxy-acetophenone-S-methylthiosemicarbazone

The N2O2-tetradentate Schiff-base complex of zinc(II) was synthesized by the template reaction of 5-ethoxy-2-hydroxy-acetophenone-S-methylthiosemicarbazone and 2-hydroxy-benzaldehyde (1)/2-hydroxy-4-methoxy-benzaldehyde (2). The compounds were characterized by elemental analysis, UV–visible, FT-IR, 1H NMR spectra, and thermogravimetric analyses. Antioxidant activities of the compounds were determined with Cupric Reducing Antioxidant Capacity and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays. The molecular geometries and vibrational frequencies were calculated using density functional theory (DFT/B3LYP) with the 6-311++G(d,p) basis set. The 1H NMR chemical shift values of the ligand and complexes in the ground state were calculated with the gauge-independent atomic orbital (GIAO) approach applying the same method and the basis set and compared with the experimental data. Using the TD-DFT method, electronic absorption spectra of the complexes were predicted at the same level. Also, the non-covalent interaction (NCI) plot index analysis reveals the presence of different kinds of non-covalent interactions in all complexes.

Synergy in the Microbial Cyclic Lipopeptide/Petroleum-Derived Surfactant Mixture Can Reduce the Total Surfactant Consumption

We report the synergistic effect of the addition of a microbial cyclic lipopeptide, surfactin (SF), to the most common petroleum-derived surfactant, sodium dodecyl sulfate (SDS). The addition of a small amount of SF (0.1 mol %) to an aqueous solution of SDS reduces the critical micelle concentration (CMC) of SDS from 10–3 to 10–6 M order. The addition of SF to SDS at various ratios lowered the surface tension at the CMC of SDS, indicating CMC reduction and, thus, the minimization of total SDS consumption without loss of surface activity. Surface tension measurement and nuclear magnetic resonance spectroscopy were conducted to analyze the synergy between SDS and SF in aqueous solutions as a function of composition. The interaction parameters of the mixed monolayer and mixed micelles were negative, indicating the occurrence of attractive interactions between SDS and SF, which were stronger than those among the individual surfactants. Moreover, the surface tension at the CMC, area occupied per surfactant molecule, difference in the interaction parameter, and 1H NMR chemical shift values of the SDS/SF mixtures as a function of their composition exhibited an extremum at a mole fraction of 0.7. These results suggest that SF has the peculiarities of encapsulation of the anionic surfactant of SDS within the inner cavity and can screen the electrostatic repulsion of SDS via the formation of their inclusion complex at SDS:SF = 2:1, which facilitates the formation of mixed monolayers and micelles in a more stable state.

Green synthesis, Single‐Crystal X‐RD, Hirshfeld Analysis and Anti‐Covid‐19 Molecular Docking Investigation of Symmetrical Azines

AbstractThe 1,2‐bis(3,4‐dimethoxybenzylidene)hydrazine (VAHD) and 1,2‐bis(3‐methoxy‐4‐hydroxybenzylidene)hydrazine (VNHD) are synthesised in a solvent free and catalyst free by greener method (MW). Both the compounds are characterized by FT‐IR,1H NMR and 13C NMR spectral studies. Single crystal XRD analysis provides more information on the structure of the compounds VAHD and VNHD. The energy gap (Eg), frontier orbital energies (EHOMO, ELUMO) and reactivity parameters like chemical hardness and global hardness andMulliken charges are calculated using density functional theory with B3LYP/6‐311++G(d,p) basis set. The experimental and theoretical calculated IR frequencies and NMR chemical shifts values are compared by DFT method. Hirshfeld surface analysis was conducted to study structure and molecular properties. Molecular docking of symmetrical azine at the active sites of SARS‐COVID receptors was investigated. Furthermore, the swissADME online application was used to analyse the physicochemical and pharmacokinetic features of the compounds (VAHD and VNHD).