Ultrasound assisted synthesis of some new 1,3,4-thiadiazole and bi(1,3,4-thiadiazole) derivatives incorporating pyrazolone moiety

Novel substituted 1,3,4-thiadiazole and bi(1,3,4-thiadiazole) were synthesized from reaction of 1-methyl-5-oxo-3-phenyl-2-pyrazolin-4-thiocarbox-anilide with a series of different hydrazonyl halides or N,N'-diphenyl-oxalodihydrazonoyl dichloride. The reactions were carried out under both conventional and ultrasonic irradiation conditions. In general, improvement in rates and yields were observed when reactions were carried out under sonication compared with classical condition. Structures of the products were established on analytical and spectral data.     

In silico studies,synthesis and anticancer activity of novel diphenyl ether-based pyridine derivatives

Molecular Diversity - A series of novel 2-amino-4-(3-hydroxy-4-phenoxyphenyl)-6-(4-substituted phenyl) nicotinonitriles were synthesized and evaluated against HepG2, A-549 and Vero cell lines....     

Unravelling the anticancer potency of 1,2,4-triazole-N-arylamide hybrids through inhibition of STAT3: synthesis and in silico mechanistic studies

Molecular Diversity - The discovery of potent STAT3 inhibitors has gained noteworthy impetus in the last decade. In line with this trend, considering the proven biological importance of...     

Design,synthesis, cytotoxicity and molecular modeling studies of some novel fluorinated pyrazole-based heterocycles as anticancer and apoptosis-inducing agents

Molecular Diversity - 3,5-Diamino-4-(3-trifluoromethylphenyldiazenyl)-1H-pyrazole was used as a starting scaffold for the synthesis of new pyrazole-based heterocycles to study their effects on the...     

Design,synthesis, in silico and in vitro evaluation of novel diphenyl ether derivatives as potential antitubercular agents

Molecular Diversity - Diphenyl ether derivatives inhibit mycobacterial cell wall synthesis by inhibiting an enzyme, enoyl-acyl carrier protein reductase (InhA), which catalyses the last step in the...     

High pressure effect on structural and mechanical properties of some LnO (Ln=Sm, Eu, Yb) compounds

The structural and mechanical properties of LnO (Ln=Sm, Eu, Yb) compounds have been investigated using a modified interionic potential theory, which includes the effect of Coulomb screening. We predicted a structural phase transition from NaCl (B₁)- to CsCl (B₂)-type structure and elastic properties in LnO compounds at very high pressure. The anomalous properties of these compounds have been correlated in terms of the hybridisation of f-electrons of the rare earth ion with conduction band and strong mixing of f-states of lanthanides with the p-orbital of neighbouring chalcogen ion. For EuO, the calculated transition pressure, bulk modulus and lattice parameter are close to the experimental data. The nature of bonds between the ions is predicted by simulating the ion-ion (Ln-Ln and Ln-O) distances at high pressure. The second order elastic constants along with shear modulus and Young's modulus, elastic anisotropy and Poisson's ratio are also presented for these oxides.     

Optical,physical and structural studies of boro-zinc tellurite glasses

To investigate the modification effect of the modifier ZnO on boro-tellurite glass, a series of glasses with compositions 50B₂O₃–(50?x)ZnO–xTeO₂ have been prepared by conventional melt quenching technique. Amorphous nature of the samples was confirmed through X-ray diffraction technique. Optical absorption and IR structural studies are carried out on the glass system. The optical absorption studies revealed that the cutoff wavelength increases while optical band gap (E_opt) and Urbach energy decreases with an increase of ZnO content. Refractive index evaluated from E_opt was found to increase with an increase of ZnO content. The compositional dependence of different physical parameters such as density, molar volume, oxygen packing density, optical basicity, have been analyzed and discussed. The IR studies showed that the structure of glass consists of TeO₄, TeO₃/TeO₃₊₁, BO₃, BO₄ and ZnO₄ units.     

Neutron studies of structural changes in amorphous C60 fullerite under temperature, pressure, and thermobaric effects

The structural behavior of amorphous fullerites obtained as a result of mechanical activation and thermal, baric, and thermobaric effects is studied via neutron diffraction. It is shown that the phase transition between the molecular crystal (fullerite) and atomic crystal (graphite) phases in the nanoscale state occurs through intermediate amorphous phases.     

The synthesis, characterization and optical properties of novel 1,3,4-oxadiazole-containing imidazo[1,5-a]pyridine derivatives

A series of novel substituted 1,3,4-oxadiazole derivatives were synthesized by the reaction of 3-butyl-1-chloroimidazo[1,5-a]pyridine-7-carbohydrazide with propionyl chloride and substituted benzoic chloride in the presence of phosphorus oxychloride. The compounds were characterized using IR, ¹H NMR, ¹³C NMR and HRMS. Absorption and fluorescence spectra were measured in dichloromethane; an intense absorption maxima was noted at ca. 290 nm and emission maxima was noted at ca. 470 nm. The absorption spectra of the 1,3,4-oxadiazole derivatives reveal that a phenyl and an ethyl group attached to the 1,3,4-oxadiazole ring markedly influenced the maximum absorption. The structures based on density function theory (DFT) calculation show planar configurations for the compounds. The calculated molecular orbital correlates well with their absorption.     

Structure-based virtual screening,in silico docking,ADME properties prediction and molecular dynamics studies for the identification of potential inhibitors against SARS-CoV-2 Mpro

COVID-19 is a viral pandemic caused by SARS-CoV-2. Due to its highly contagious nature, millions of people are getting affected worldwide knocking down the delicate global socio-economic equilibrium. According to the World Health Organization, COVID-19 has affected over 186 million people with a mortality of around 4 million as of July 09, 2021. Currently, there are few therapeutic options available for COVID-19 control. The rapid mutations in SARS-CoV-2 genome and development of new virulent strains with increased infection and mortality among COVID-19 patients, there is a great need to discover more potential drugs for SARS-CoV-2 on a priority basis. One of the key viral enzymes responsible for the replication and maturation of SARS-CoV-2 is M^pro protein. In the current study, structure-based virtual screening was used to identify four potential ligands against SARS-CoV-2 M^pro from a set of 8,722 ASINEX library compounds. These four compounds were evaluated using ADME filter to check their ADME profile and druggability, and all the four compounds were found to be within the current pharmacological acceptable range. They were individually docked to SARS-CoV-2 M^pro protein to assess their molecular interactions. Further, molecular dynamics (MD) simulations was carried out on protein–ligand complex using Desmond at 100 ns to explore their binding conformational stability. Based on RMSD, RMSF and hydrogen bond interactions, it was found that the stability of protein–ligand complex was maintained throughout the entire 100 ns simulations for all the four compounds. Some of the key ligand amino acid residues participated in stabilizing the protein–ligand interactions includes GLN 189, SER 10, GLU 166, ASN 142 with PHE 66 and TRP 132 of SARS-CoV-2 M^pro. Further optimization of these compounds could lead to promising drug candidates for SARS-CoV-2 M^pro target.

     

Growth,structural, thermal,optical, dielectric,mechanical and laser damage threshold studies of nicotinium tartrate single crystals

An organic nonlinear optical nicotinium tartrate (NT) single crystal was grown by slow evaporation solution growth technique. The cell parameters of NT crystal were confirmed by single crystal and powder X-ray diffraction studies. The crystalline perfection of NT crystal was examined from HRXRD studies. The presence of functional groups was identified from FTIR spectral analysis. TGA and DSC studies revealed the thermal stability of NT crystal. UV–vis-NIR spectral studies showed that the NT crystal has wide transmission window in the entire visible region. The dielectric study on NT crystal established the normal dielectric behavior. The mechanical strength of NT crystal was studied by Vickers’ microhardness test. The laser damage threshold value of NT crystal was measured using Nd:YAG laser. The relative SHG efficiency of NT was measured to be 1.1 times that of KDP.     

Electrochemical and thermodynamic studies to evaluate the inhibition effect of synthesized piperidine derivatives on the corrosion of mild steel in acidic medium

Ionics - The inhibition ability of three newly synthesized piperidine sulphonamides toward the mild steel (MS) corrosion was investigated using mass loss and electrochemical techniques. The...     

Design,synthesis, in silico and biological evaluation of novel 2-(4-(4-substituted piperazin-1-yl)benzylidene)hydrazine carboxamides

A series of novel 2-(4-(4-substituted piperazin-1-yl)benzylidene)hydrazinecarboxamide derivatives has been successfully designed and synthesized to evaluate their potential as carbonic anhydrase (CA) inhibitors. The inhibitory potential of synthesized compounds against human CAI and CAII was evaluated. Compounds 3a–n exhibited \(\hbox {IC}_{50}\) values between \(1.89{-}415.1\,\upmu \hbox {M}\) against CAI and \(0.62{-}66.9\,\upmu \hbox {M}\) against CAII. Compound 3g was the most active inhibitor, with an \(\hbox {IC}_{50}\) value of \(0.62\,\upmu \hbox {M}\) against CAII. Molecular docking studies of compound 3g with CAII showed this compound fits nicely in the active site of CAII and it interacts with the zinc ion (\(\hbox {Zn}^{2+}\)) along with three histidine residues in the active site. Molecular dynamics simulation studies of compound 3g complexed with CAII also showed essential interactions which were maintained up to 40 ns of simulation. In vivo sub-acute toxicity study using 3g (300 mg/kg) was found non-toxic in adult Wistar rats.     

Advances in theoretical and experimental XAFS studies of thermodynamic properties,anharmonic effects and structural determination of fcc crystals

Thermodynamic properties, anharmonic effects and structural determination of fcc crystals have been studied based on the theoretical and experimental Debye–Waller factors presented in terms of cumulant expansion up to the third order, thermal expansion coefficient, X-ray absorption fine structure (XAFS) spectra and their Fourier transform magnitudes. The advances in these studies are performed by the further development of the anharmonic correlated Einstein model primary only for approximating three first XAFS cumulants into the method using that all the considered theoretical and experimental XAFS parameters have been provided based on only the calculated and measured second cumulants. The obtained cumulants describe the anharmonic effects in XAFS contributing to the accurate structural determination. Numerical results for Cu are found to be in good agreement with the experimental values extracted by using the present advanced method and with those obtained by the other measurements.     

Quantum-chemical modeling of structural,electronic, and spin characteristics of NV centers in nanostructured diamond: Surface effect

The effect of the surface of diamond on atomic, electronic, and spin properties of diamond nanocrystals containing single nitrogen-vacancy defects ([NV]⁻ centers) is studied. The surface was modeled with clusters C₃₃H₃₀[NV]⁻, C₆₆H₇₂[NV]⁻, which were constructed based on bulk clusters C₃₃H₃₆[NV]⁻ and C₆₉H₈₄[NV]⁻, respectively. In all cases, clusters in the triplet state S = 1 are considered with the cluster charge being −1. The geometric structure of clusters is optimized using the principle of minimization of the total energy of the system; then, the electronic and spin characteristics of clusters are calculated by the density functional theory. The isotropic and anisotropic hyperfine interaction constants of the electron spin of the NV center with the nuclear spin of the nitrogen atom and ¹³C atoms located at different sites in the cluster are calculated. It is found that, in contrast to bulk clusters with [NV]-centers in which the spin density is mainly localized at the three carbon atoms that are the nearest neighbors of the vacancy of the center, upon arrangement of the NV center in the immediate proximity to the surface, the spin density is redistributed such that it is mainly localized at the three carbon atoms that are the nearest neighbors of the nitrogen atom of the center and at C atoms that form the first atomic layer of the (111) surface of the nanocrystal.     

Infrared and 1H nuclear magnetic resonance studies of solvent effect on hydrogen bond in some pyridine n-oxide trifluoroacetates

The IR and ¹H NNR spectra are reported for the trifluoroacetates of five substituted pyridine N-oxides in five dry aprotic solvents of different polarity and studied with respect to the influence of the reaction field. Both the centre of gravity ($\text{V}$_H) of continuous absorption and the chemical shift (δ) show weak dependence upon solvent polarity. In the range of ε from 2.27 to 10.36 the continuous absorption is very similar. In acetonitrile (ε = 37.5) $\text{V}$_H is shifted. The magnitude and sign of the $\text{V}$_H shift depend on the proton acceptor properties of N-oxides and can be correlated with the position of the proton in the complex. The influence of the reaction field on OHO bonds is compared with the influence on OH?N?O^??HN⁺ bonds, and the differences in behavior of these complexes are related to their energy surface. The weak dependence of $\text{V}$_H and δ upon the reaction field in pyridine N-oxide trifluoroacetates is consistent with the single minimum energy surface postulated in the literature for the strong OHO bonds.     

Mössbauer,magnetic and ir studies of some mononuclear Fe(III) complexes

Mössbauer studies at room temperature and down to liquid nitrogen temperature were supplemented with magnetic and infrared studies of Monochloroferricbis (X-benzoate) and monochloroferricbis (X-chloroacetate). Mössbauer parameters indicate that all the complexes possess high spin configuration in the trivalent and monomeric states. Positive value of V_zz indicates that there is more negative charge in the x-y plane than in along z-axis, suggesting that Fe is penta-coordinated. Molecular weight determination also confirms that the complexes are mononuclear. The effective magnetic moment of the complexes points out to a weak field iron configuration. An attempt has been made to interpret the structure of these complexes on the basis of the measured data.     

In vitro antimicrobial evaluation and in silico studies of coumarin derivatives tagged with pyrano-pyridine and pyrano-pyrimidine moieties as DNA gyrase inhibitors

Molecular Diversity - Several coumarin-containing substitute nitrogen heterocycles have recently received considerable importance due to their diverse pharmacological properties. One-pot and rapid...     

A DFT studies of structural and quadrupole coupling constants properties in C-doped BeO nanotubes

In the framework of density functional theory (DFT), we calculated the electronic structures and the quadrupole coupling constants (CQ) in the pristine and carbon doped (C-doped) beryllium oxide nanotubes (BeONTs) for the first time. The pristine and C-doped forms of representative (10, 0) zigzag and (5, 5) armchair models of BeONTs were considered in this study. The structures are allowed to relax by performing all atomic optimization. Formation energies indicate that C-doping of Be atom (CBe form) could be more favorable than C-doping of O atom (CO form) in both zigzag and armchair BeONTs. Gap energies and dipole moments detected the effects of dopant in the (5, 5) armchair models; however, those parameters did not detect any significant changes in the C-doped (10, 0) zigzag BeONT models. The calculated nuclear quadrupole coupling constant for the Be and O nuclei reveal that the pristine models can be divided into layers of nuclei with an equivalent electrostatic environment such that those nuclei at the ends of tubes end up in a strong electrostatic environment when compared to the other nuclei along the length of tubes. Comparison with the available data on the pristine BeONTs reveals the influence of C-doping on the CQ parameters of Be and O atoms in the C-doped structures. For most lattice sites, the degree of influence on the CQ parameters of the zigzag model is larger than that of the armchair model. The calculations were performed based on the B3LYP DFT method and 6-31G^∗ standard basis sets using the Gaussian 09 program package.     

Theoretical studies on the structural, electronic, and optical properties of Cu2CdGeSe4

We investigate the electronic structure for Cu₂CdGeSe₄ in stannite structure with the first-principles method. This crystal is the direct band gap compound. In addition, the dielectric function, absorption coefficient, reflectivity, and energy-loss function are studied using the density functional theory within the generalized gradient approximation. We discuss the optical transitions between the valence bands and the conduction bands in the spectra of the imaginary part of the dielectric function at length. We also find a very high absorption coefficient and wide absorption spectrum for this material. The prominent structures in the spectra of reflectivity and energy-loss function are discussed in detail.