Egap Values Research Articles

Linear electronic relationship of surface functionalized fly ash and substituted phenols on bactericidal activity with the computational study

AbstractFly ash is a solid waste by‐product obtained from coal‐burning power plants. It is a silico‐aluminate material with an admixture of several metal oxides, which finds an application in geopolymers, zeolites, cement, catalysts, etc. The present article aims to assess the antibacterial activity of fly ash and substituted phenols against Escherichia coli and Staphylococcus in broth and agar cultures, respectively. High‐Temperature Activated Fly Ash (TAFA) shows significant bactericidal activity against gram positive (+) and negative (−) bacteria as compared to Mechanically Activated Fly Ash (MAFA) and Waste Polyethylene Coated Fly Ash (WPCFA), which attribute to the augmentation of mullite phase (lacking charge balancing cation) of fly ash at high temperature. These modified fly ash (TAFA, MAFA, and WPCFA) were characterized by Fourier Transform Infra Red (FT‐IR), Scanning Electron Microscope (SEM), and X‐Ray Diffraction (XRD) techniques. The substituted phenols further explored the significance of charge on the antibacterial properties. The para‐substituted phenols with groups having (+) mesomeric effect M > (−) I Inductive effect and ortho substituents with (+) I effect shows a linear electronic relationship with antibacterial properties with gram (+) bacteria, owing to charge augmentation at oxygen atom of phenoxide ion due to electronic effects. Further, the bactericidal efficacy was less significant on gram (−) bacteria. Small energy gap (Egap) values corroborated the chemical reactivity of phenols and substituted phenols. The antimicrobial potential of phenol/substituted phenols can be correlated with global descriptors. Molecular Electrostatic Potential (MEP) maps obtained through Density Functional Theory (DFT) indicate the nucleophilic centers in the molecular structure.

Exploring the electronic structure of tetrathienylethene derivatives for OLED applications: A theoretical study

AbstractThe B3LYP/6‐31G(d,p) method is applied to investigate the structural and electronic properties of tetrathienylethene (TTE) derivatives, specifically for the properties of 14 distinct TTE derivatives. The results indicate that the T1–T14 derivatives exhibit numerous advantages over the parent TTE compound. Notably, substituents predominantly impact the LUMO energy level of the TTE parent compound. Additionally, all modified molecules exhibit lower energy band gaps (Egap) and improved charge transfer capacity relative to TTE. These findings suggest that the T1–T14 derivatives may be promising candidates for use as materials in OLED applications. The values of chemical hardness (η) indicate that all compounds T1–T14 manifest greater softness relative to the parent compound TTE. This correlation aligns with the calculated Egap values, wherein compounds T1–T14 consistently exhibit smaller Egap values compared to the TTE compound. These research findings indicate that compounds T1 and T10 display remarkable and harmonious charge transfer capabilities. This is evident from their corresponding values of λh and λe, which stand at 0.39/0.41 and 0.41/0.41 eV, respectively. Remarkably, compound T1 exhibits the most pronounced absorption peak, occurring at a wavelength of 441 nm. This absorption is accompanied by the highest oscillator strength recorded for the compound, reaching a value of 0.638.

Structural investigation, photoluminescence, and antibacterial properties of purified palygorskite impregnated with α-Ag2WO4 microcrystals

The presence of organic contaminants in aquatic environments, such as antibiotics, induces the proliferation of resistant pathogens, giving rise to the need to develop new materials with antimicrobial action. Therefore, in this work, we report new results to purified Palygorskite (P-Pal) clay with a surface impregnated with alpha-silver tungstate (α-Ag2WO4) microcrystals abbreviated as AWO, and its structural, photoluminescence (PL) and antibacterial investigation for inactivation of gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus) bacterial strains at concentrations of P-Pal/x%/AWO from x = 4–32%. X-ray diffraction patterns, Rietveld refinement data, and Fourier transform infrared spectroscopy confirmed that the P-Pal is composed of two crystal phases (Mg2.074Al1.026) (Si4O10.48)2(OH)2(H2O)10.68 with an orthorhombic structure and α-SiO2 with a rhombohedral structure; already the AWO microcrystals are single-phase with an orthorhombic structure and their vibrational modes. Ultraviolet–visible spectroscopy shows an increase in the Egap values for mixed systems compared to the isolated materials, indicating a synergistic interaction between the energy levels of both materials. Field emission scanning electron microscopy images display the presence of several elongated fibers and hexagonal crystals in the P-Pal clay and rod-like AWO microcrystals. In contrast, P-Pal clay/AWO microcrystals exhibit the presence of all three crystal shapes. Photoluminescence spectra show a high emission for the P-Pal clay/4% AWO microcrystals, indicating a better energy band gap synergistic. Finally, the microbiological tests show that as the proportion of AWO crystals on the P-Pal clay surface increases, there is a rise in antibacterial activity.

Evaluation of novel pyridoxal isonicotinoyl hydrazone (PIH) derivatives as potential anti‐tuberculosis agents: An in silico investigation

AbstractThis investigation employed computational methodologies to assess the therapeutic potential of derivatives (1–16) of pyridoxal isonicotinoyl hydrazone (PIH) as potential treatments for tuberculosis. Various computational techniques, including molecular dynamics simulation, molecular docking, density functional theory, and global chemical descriptors, were employed to analyze the interactions between the ligands and target proteins. Docking results indicated that ligands 6, 7, 8, and rifampin exhibited binding affinities of −8.4, −7.4, −9.2, and − 7.2 kcal mol−1, respectively, against mycobacterium tuberculosis enoyl acyl carrier protein reductase (INHA), with ligand 8 demonstrating superior inhibition. Molecular dynamics (MD) simulations were utilized to assess the stability of protein‐ligand interactions. Remarkably, the Root Mean Square Deviation (RMSD) of the INHA‐ligand 8 complex remained minimal, with peak values at .40, .56, .37, and .50 nm at temperatures of 300, 305, 310, and 320 K, respectively. This suggests superior stability compared to the reference drug rifampin and INHA complex, which exhibited an RMSD range of .2 to .8 nm at 300 K. Furthermore, analysis using Frontier Molecular Orbital (FMO) revealed that the Egap value of ligand 8 (4.407 eV) is lower than all the reference drugs except rifampin. This comprehensive theoretical analysis positions ligand 8 as a promising candidate for anti‐tuberculosis drug development, underscoring the need for further exploration through in vitro and in vivo studies.

Temperature-dependent optical bandgap of TiO2 under the Anatase and Rutile phases

A crucial step in developing new and/or more efficient devices relies on the detailed knowledge of the properties of their main (elemental or combined) parts. The same applies to titanium dioxide TiO2 that forms the basis of today numerous applications whose performances are determined by the presence or relative amount of the Anatase (A-) and Rutile (R-) most common phases of TiO2. Whereas the basic structural characteristics of these two polymorphs are very well-established, some of their optical aspects still deserve attention. With these ideas in mind this work presents a comprehensive investigation of the optical bandgap Egap of TiO2 under the Anatase and Rutile phases. The study considered pure A-TiO2 and R-TiO2 samples in the form of powder, and optical reflectance and Raman spectroscopy in the 83–823 K temperature range. In addition to reliable Egap values the study explores their temperature-dependent Egap(T) behavior that is expected to assist future advancements in the field of TiO2-based materials and devices (thin films, interfaces, low-dimensional systems, and photocatalytic and solar cells, for example).

Exploring the anticancer and antibacterial potential of naphthoquinone derivatives: a comprehensive computational investigation.

This study investigates the potential of 2-(4-butylbenzyl)-3-hydroxynaphthalene-1,4-dione (11) and its 12 derivatives as anticancer and biofilm formation inhibitors for methicillin-resistant staphylococcus aureus using in silico methods. The study employed various computational methods, including molecular dynamics simulation molecular docking, density functional theory, and global chemical descriptors, to evaluate the interactions between the compounds and the target proteins. The docking results revealed that compounds 9, 11, 13, and ofloxacin exhibited binding affinities of -7.6, -7.9, -7.5, and -7.8kcalmol-1, respectively, against peptide methionine sulfoxide reductase msrA/msrB (PDB: 3E0M). Ligand (11) showed better inhibition for methicillin-resistant staphylococcus aureus msrA/msrB enzyme. The complex of the 3E0M-ligand 11 remained highly stable across all tested temperatures (300, 305, 310, and 320K). Principal Component Analysis (PCA) was employed to evaluate the behavior of the complex at various temperatures (300, 305, 310, and 320K), demonstrating a total variance of 85%. Convergence was confirmed by the eigenvector's cosine content value of 0.43, consistently displaying low RMSD values, with the minimum observed at 310K. Furthermore, ligand 11 emerges as the most promising candidate among the compounds examined, showcasing notable potential when considering a combination of in vitro, in vivo, and now in silico data. While the naphthoquinone derivative (11) remains the primary candidate based on comprehensive in silico studies, further analysis using Frontier molecular orbital (FMO) suggests while the Egap value of compound 11 (2.980eV) and compound 13 (2.975eV) is lower than ofloxacin (4.369eV), indicating their potential, so it can be a statement that compound 13 can also be investigated in further research.

Influence of acceptors on the optical nonlinearity of 5H-4-oxa-1,6,9-trithia-cyclopenta[b]-as-indacene-based chromophores with a push-pull assembly: a DFT approach.

Herein, a series of compounds (TPD1-TPD6) having a D-π-A architecture was quantum chemically designed via the structural modulation of TPR. Quantum chemical calculations were employed to gain a comprehensive insight into the structural and optoelectronic properties of the designed molecules at the M06/6-311G(d,p) level. Interestingly, all the designed chromophores displayed narrow energy gaps (2.123-1.788 eV) and wider absorption spectra (λmax = 833.619-719.709 nm) with a bathochromic shift in comparison to the reference compound (λmax = 749.602 nm and Egap = 3.177 eV). Further, Egap values were utilized to evaluate global reactivity parameters (GRPs), which indicate that all the chromophores expressed higher softness (σ = 0.134-0.559 eV-1) and lower hardness (η = 4.155-4.543 eV) values than the reference chromophore. Efficient charge transfer from donors towards acceptors was noted through FMOs, which was also supported by DOS and TDM analyses. Overall, the TPD3 derivative exhibited a remarkable reduction in the HOMO-LUMO band gap (1.788 eV) with a red shift as λmax = 833.619 nm. Furthermore, it exhibited prominent linear and non-linear characteristics such as μtotal = 24.1731 D, 〈α〉 = 2.89 × 10-22 esu, and βtotal = 7.24 × 10-27 esu, among all derivatives. The above findings revealed that significant non-linear optical materials could be achieved through structural tailoring with studied efficient acceptors.

Photovoltaic and Optical Characterization of Organic Heterocyclic 6,6′‐Dibromoindigotin Crystal Under Changing Solvent Polarity by DFT Analysis

AbstractThe photovoltaic and optical properties of 6,6′‐dibromoindigotin (DBI) crystal under changing solvent polarity are investigated through DFT analysis. It includes geometry optimization, global reactivity, UV–vis analysis, open circuit voltage (Voc), FMOs, and NBO analysis. The highest HOMO‐LUMO gap (Egap) value is found for the gaseous phase (1.82 eV), while the lowest Egap is found for dichloro methane (1.64 eV), and intermediate values with the other solvents. The molecule has a high IP of 2.48 eV, low EA of 0.74 eV, moderate polarity, and hardness (η). The maximum absorption wavelengths (λmax) of the compound in different solvents are dichloromethane and DMSO (373 nm), chloroform (372 nm), methanol and water (371 nm), toluene (367 nm), and gaseous (356 nm). Their Voc range is 0.2–0.28 eV. Among all, chloroform demonstrates the highest performance with a fill factor (FF) of 0.8630, normalized open circuit (Nor. Voc) of 31.69 eV, and Jsc of 26.47 mA cm−2. Toluene also shows promising results with an FF of 0.8060, Nor. Voc of 19.71 eV, and Jsc of 21.19 mA cm−2. Water, although not as effective as other solvents, still exhibits respectable values with an FF of 0.8315, Nor. Voc of 23.96 eV, and Jsc of 24.63 mA cm−2.

Transmittal Effect Evaluation of Heterocyclic Rings on Nonlinear Optical Ambit of Benzotrithiophene-Based Push-Pull Driving Materials: a Theoretical Approach

To obtain extensive insights into NLO properties, herein, two series of benzotrithiophene (BTT) based organic compounds (MS1-MS5 and MP1-MP5) containing D1-π 1-D2-π 2-A-type framework have been designed. The structural tailoring was accomplished via the incorporation of thiophene and pyrrole units in MS1-MS5 and MP1-MP5, respectively at the region of π 2 in each derivative. Quantum chemical calculations including: frontier molecular orbitals (FMOs), natural population analysis (NPA), UV-Vis investigation, transition density matrix (TDMx), density of state (DOS), molecular electrostatic potential (MEP) and natural bond orbitals (NBOs) analyses were accomplished at MPW1PW91/6-311G(d,p) functional to determine the influence of π-linkers on the optical response of designed chromophores. Conclusively, remarkable NLO results were obtained for thiophene-based derivatives (MS1-MS5) as compared to pyrrole-based derivatives (MP1-MP5). Interestingly, among all the derivatives, minimum Egap values of 2.248 and 2.264 eV were observed for MS4 and MS5, respectively, and the Egap values were found in the following decreasing order: MS1>MS3>MS2>MS5>MS4. Surprisingly, MS4 and MS5 displayed maximum amplitudes of < α> i.e., 2.44 × 10−22 and 2.65 × 10−22 esu as well as < γ> such as: 3.91 × 10−32 and 4.35 × 10−32 esu, respectively. Moreover, the declining trend of < γ> was observed as follows: MS5 > MS4 > MS2 > MS3 > MS1. In a nutshell, this investigation may provide a new insight for the use of these BTT-based organic chromophores especially MS4 and MS5 for potential NLO-based hi-tech applications.

Potansiyel JNK1 İnhibe Edici Aktiviteye Sahip 2-((4-(dimetilamino)benziliden)amino)-5-metilfenol’ün Sentezi, Teorik Çalışmaları, Sitotoksisitesi

Cisplatin, doxorubicin, hydroxycamptothecin, leucovorin, vincristine and 5-fluorouracil resistance of cancer cells are associated with the activities of C-Jun N-Terminal Kinase 1 (JNK1). Inhibition of the JNK1 by pharmacological agents could be a beneficial attempt for reversing the chemoresistance of various cancer cells. However, there is no FDA-approved JNK inhibitor for safe use in clinics in today’s clinics. In this study, a Schiff base 2-((4-(dimethylamino)benzylidene)amino)-5-methylphenol, (7S4) has been synthesized and characterized by 1H, 13C-NMR, FT-IR and elemental analysis. The stable geometry of 7S4 has been determined by DFT method with Gaussian09 program (B3LYP/6-311g++(d,p))). The Gibbs Free energies, stable tautomer forms, H-bond, Mulliken charges, dipole moment, natural bond orbital (NBO), HOMO, LUMO and band gap energy (EGAP), molecular electrostatic potential (MEP) and solvent accessibility surface areas (SASA) have been calculated. Drug-likeness, anticancer and JNK1 inhibitory activities of 7S4 have been evaluated. Enol tautomer form of trans 7S4 was characterized as the most stable structure. 7S4 was observed to be a reactive compound in chemical reactions with a low EGAP value. In addition, high and low electron density regions of 7S4 are responsible for the establishment of chemical bonds in biological systems. 7S4 exhibited strong druggability with the agreement on Lipinski, Ghose, Veber, Egan, and Muegge rules. Cytotoxicity tests and molecular docking revealed that 7S4 poses a potential JNK1 inhibitor activity.

Adsorption Features of Tetrahalomethanes (CX4; X = F, Cl, and Br) on β12 Borophene and Pristine Graphene Nanosheets: A Comparative DFT Study.

The potentiality of the β12 borophene (β12) and pristine graphene (GN) nanosheets to adsorb tetrahalomethanes (CX4; X = F, Cl, and Br) were investigated using density functional theory (DFT) methods. To provide a thorough understanding of the adsorption process, tetrel (XC-X3∙∙∙β12/GN)- and halogen (X3C-X∙∙∙β12/GN)-oriented configurations were characterized at various adsorption sites. According to the energetic manifestations, the adsorption process of the CX4∙∙∙β12/GN complexes within the tetrel-oriented configuration led to more desirable negative adsorption energy (Eads) values than that within the halogen-oriented analogs. Numerically, Eads values of the CBr4∙∙∙Br1@β12 and T@GN complexes within tetrel-/halogen-oriented configurations were -12.33/-8.91 and -10.03/-6.00 kcal/mol, respectively. Frontier molecular orbital (FMO) results exhibited changes in the EHOMO, ELUMO, and Egap values of the pure β12 and GN nanosheets following the adsorption of CX4 molecules. Bader charge transfer findings outlined the electron-donating property for the CX4 molecules after adsorbing on the β12 and GN nanosheets within the two modeled configurations, except the adsorbed CBr4 molecule on the GN sheet within the tetrel-oriented configuration. Following the adsorption process, new bands and peaks were observed in the band structure and density of state (DOS) plots, respectively, with a larger number in the case of the tetrel-oriented configuration than in the halogen-oriented one. According to the solvent effect affirmations, adsorption energies of the CX4∙∙∙β12/GN complexes increased in the presence of a water medium. The results of this study will serve as a focal point for experimentalists to better comprehend the adsorption behavior of β12 and GN nanosheets toward small toxic molecules.

Structural Characterization and Molecular Docking Screening of Most Potent 1,2,4-Triazine Sulfonamide Derivatives as Anti-Cancer Agents

One of the biggest problems facing contemporary medicine is cancer. New approaches to therapy are required due to the difficult and prolonged treatment, the numerous adverse properties of the medications employed, and the developing confrontation of neoplastic cells to treatment. Ten 1,2,4-triazine sulfonamide derivatives (1–10) were chosen for the first time in the current work, and their chemical structures were examined by DFT studies. The in silico flexible docking analysis of the chosen receptors involved in cancer development and metastasis (3RHK, 5GTY, 6PL2, and 7JXH) revealed that the selected compounds are the most promising. The binding affinity of compounds 10, 2, 6, and 4 is much better than the standard drug, Erlotinib, whereas compounds 9, 3, 1, and 7 showed better affinities as compared to standard drugs Neratinib and Tepotinib in the case of 3RHK receptor. The binding affinity against the 5GTY receptor of compounds 10, 5, and 3 is much better than the standard drug Tepotinib, and compounds 7, 6, 2, 4, 1, 8, and 9 showed better than Erlonitib and Neratinib. The binding affinity against the 6PL2 receptor of compounds 8, 3, 5, 4, 9, and 1 is much better than the standard drug Tepotinib. Compounds 10, 6, 7, and 2 were better than Erlotinib and Neratinib. All selected drugs showed better binding affinities than the standard anti-cancer drug Neratinib in the case of the 7JXH receptor, whereas compounds 2, 10, 5, 9, and 8 are better than Erlotinib. In silico ADME experiments supported the identified compounds’ drug similarity. According to the MEP calculations, compounds 3 through 10 can interact non-covalently. The interactions might take the form of σ- and π-hole interactions. Softest compound 4 has the smallest energy gap, with an E-gap value of 3.25 Ev. Compound 4 has the largest energy gap at 3.41 eV. Compound 5 superior electron donor has the highest HOMO energy (6.5470 eV for HOMO). Compound 2 has the lowest LUMO energy, which suggests that it would be the best electron acceptor (ELUMO = 5.766364 eV).

Bending Effect on the Electronic Properties and Nonlinear Optical Responses of Linear Porphyrin Oligomer

AbstractPhysical bending provides a more stable and controllable method to modify the electronic properties and device applications compared to chemical doping/surface modification in traditional optoelectronic materials. The bending effect on the electronic properties and nonlinear optical (NLO) responses of linear porphyrin oligomer is explored using quantum chemistry methods by designing a series of curved structures with different bending degrees. The highest occupied molecular orbital−lowest unoccupied molecular orbital energy gap (Egap) of the linear porphyrin oligomer decreases after being bended to form the curved structures, and the Egap values and orbital distributions show independent behavior on bending degree. In the electronic absorption spectra, the maximum absorptions mainly come from the S0 → S1/S0 → S2 transitions with the characteristic of local excitation. The NLO response presents a tendency to increase and then decrease with decreasing the bending degree, which is in good accordance with the widely used two‐level model. The curved frameworks as well as the results offer guidelines for novel organic NLO device design and fabrication.

The Relationship between Photoluminescence Emissions and Photocatalytic Activity of CeO2 Nanocrystals.

In this work, we focus on understanding the morphology and photocatalytic properties of CeO2 nanocrystals (NCs) synthesized via a microwave-assisted solvothermal method using acetone and ethanol as solvents. Wulff constructions reveal a complete map of available morphologies and a theoretical-experimental match with octahedral nanoparticles obtained through synthesis using ethanol as solvent. NCs synthesized in acetone show a greater contribution of emission peaks in the blue region (∼450 nm), which may be associated with higher Ce3+ concentration, originating shallow-level defects within the CeO2 lattice while for the samples synthesized in ethanol a strong orange-red emission (∼595 nm) suggests that oxygen vacancies may originate from deep-level defects within the optical bandgap region. The superior photocatalytic response of CeO2 synthesized in acetone compared to that of CeO2 synthesized in ethanol may be associated with an increase in long-/short-range disorder within the CeO2 structure, causing the Egap value to decrease, facilitating light absorption. Furthermore, surface (100) stabilization in samples synthesized in ethanol may be related to low photocatalytic activity. Photocatalytic degradation was facilitated by the generation of ·OH and ·O2- radicals as corroborated by the trapping experiment. The mechanism of enhanced photocatalytic activity has been proposed suggesting that samples synthesized in acetone tend to have lower e'─h· pair recombination, which is reflected in their higher photocatalytic response.

Adsorption of Favipiravir on pristine graphene nanosheets as a drug delivery system: a DFT study.

The efficiency of pristine graphene (GN) in the delivery process of the Favipiravir (FPV) anti-COVID-19 drug was herein revealed within the FPV⋯GN complexes in perpendicular and parallel configurations in terms of the density functional theory (DFT) method. Adsorption energy findings unveiled that the parallel configuration of FPV⋯GN complexes showed higher desirability than the perpendicular one, giving adsorption energy up to -15.95 kcal mol-1. This favorability could be interpreted as a consequence of the contribution of π-π stacking to the overall strength of the adsorption process in the parallel configuration. Frontier molecular orbitals (FMO) findings demonstrated the ability of the GN nanosheet to adsorb the FPV drug by the alteration in the EHOMO, ELUMO, and Egap values before and after the adsorption process. Based on Bader charge results, the FPV drug and GN sheet exhibited electron-donating and -accepting characters, respectively, which was confirmed by the negative sign of the computed charge transfer (Qt) values. The FPV(R)⋯T@GN complex showed the most desirable Qt value of -0.0377e, which was in synoptic with the adsorption energy pattern. Electronic properties of GN were also altered after the adsorption of the FPV drug in both configurations, with more observable changes in the parallel one. Interestingly, the Dirac point of the GN sheet coincided with the Fermi level after the adsorption process, indicating that the adsorption process unaffected the presence of the Dirac point. The occurrence of the adsorption process was also noticed by the existence of new bands and peaks in the band structure and DOS plots, respectively. Short recovery time rendered the GN nanosheet an efficient FPV drug delivery system. The obtained findings provide new insight into the biomedical applications of the GN sheet as a promising drug delivery system.

Heat treatment influence on structural and optical properties of NiWO4 crystals

In this work, we investigated the effect of heat treatment on the structural and optical behavior of NiWO4 crystals synthesized by coprecipitation followed by the hydrothermal method, with post-treatment at different temperatures., Rietveld refinement and Raman spectra indicate that NiWO4 crystals have a wolframite-like monoclinic structure with a space group (P2/c) and a symmetry point group (C2h4). A preferential growth in the (011) planes was observed at 500 ​°C, confirmed by XRD, theoretical and documented, thus, crimped on the y-axis of partials (W) tung event sequences for modeling unit cells/crystals in this temperature range in TGA and DSC. In Raman spectroscopy, the NiWO4 spectrum gradually changed in the spectra from its nanometer character and became a bulk material. The Egap values showed a tendency of reduction with increasing heat treatment up to 500 ​°C (2.75 ​eV), increasing from there. Such alterations being confirmed in the colorimetric analysis, where from the temperature of 500 ​°C/2 ​h the material acquired the yellow color and it becomes intended.

Vacancy defects transform zinc tellurite glass from insulator to semiconductor: A first-principles prediction

The effect of vacancy defects on the zinc tellurite glass (ZnTeO3) was investigated by performing density functional theory using GGA-PBESOL functional and norm-conserving pseudopotential. The effect of the inclusion of Hubbard-U correction for only Ud, Zn state or Up, O state or both states was investigated to obtain the experimental band gap. The lattice parameters, band structure, and density of states of ZnTeO3 were predicted. The value of Up, O has a significant impact on the band gap (Egap) value of ZnTeO3. Our calculated Egap exactly agrees with the experimental value (4.1 eV). The Egap values of the vacancies were significantly decreased as compared to the perfect structure. The Egap values of the Zn-vacancy and Te-vacancy were 2.5 eV and 2.0 eV, respectively. Three kinds of O vacancies were studied and their Egap values ranged from 2.2 eV to 2.5 eV. The vacancy defects changed the insulating character of ZnTeO3 to semiconductor behavior, which may have promising applications. The vacancies stability follows the order of perfect crystal > O-vacancy > Zn-vacancy > Te-vacancy, i.e., based on their cohesive energies. The formation energies were calculated and indicated that the spontaneous formation of the vacancies is impossible; however, the formation of the O-vacancy was determined to be the most probable, followed by Zn-vacancy and then Te-vacancy under specific conditions. The optical properties (refractive index, reflectivity, dielectric function, optical conductivity, and loss function) and thermodynamic properties of zinc ZnTeO3 and its vacancy defects were predicted.

Structural investigation and sonophotocatalytic properties of the solid solutions Sr(Mo1−xWx)O4 crystals synthesized by the sonochemical method

In this paper, the solid solutions of strontium molybdate-tungstate [Sr(Mo1−xWx)O4] crystals with (x = 0, 0.25, 0.50, 0.75, and 1) were synthesized by the sonochemical method. Their structure, morphology, optical, and sonophotocatalytic properties were performed in function of the replacement of Mo6+ by W6+ cations into the lattice. Their structure and elemental composition were characterized using X-ray diffraction, Rietveld refinement, micro-Raman, energy-dispersive X-ray, and Fourier-transform infrared spectroscopies proving that all samples are monophasic, crystalline, and exhibit a scheelite-type tetragonal structure. Field-emission scanning electron microscopy images revealed the octahedral and dumbbell-like morphologies for SrMoO4 and SrWO4 crystals. Moreover, it is noted to pass through spindle-like morphology for the microcrystals containing both Mo6+ and W6+ cations (x = 0.25, 0.50, and 0.75). Ultraviolet-visible diffuse reflectance spectroscopy showed a directly proportional increase in the optical band gap (Egap) values from 4.27 to 5.01 eV. These data indicate an increase in the intermediary electronic levels between valance and conduction bands with the increase in the concentration of W6+ cations in the lattice. Finally, we have obtained good sonophotocatalytic performances for SrMoO4 crystals (90%), and mainly to Sr(Mo0.25W0.75)O4 crystals (98%) in the degradation of Rhodamine B dye until 240 min under UV-C light.

Sensing cyclosarin (a chemical warfare agent) by Cucurbit[n]urils: A DFT/TD-DFT study

The detection of toxic chemical warfare agents (CWAs) has been a prime aim of the scientific community. The non-toxic nature and capability to mimic the biological systems of the Cucurbit[n]uril (CB[n]), a macrocyclic molecular family has made them good candidates for capturing and sensing the CWAs. Here density functional theory (DFT) and time-dependent density functional theory (TD-DFT) has been exploited to study the sensing of an important nerve agent i.e., cyclosarin molecule with CB[n] (n = 5–8) host molecules. M06-2X (out of twelve functionals tested) offers good agreement with the experiment in terms of mean absolute deviations (MAD) of bond lengths and bond angles. The cyclosarin binding with CB[6] is thermodynamically favoured compared to other CB[n]s indicated by vander Waals interactions through Bader's quantum theory of “Atoms in Molecules” (QTAIM) calculations. This binding stability fizzles out on further addition of cyclosarin guest (total five) with the host molecules. The inclusion complexes having cyclosarin within the CB[6-8] host cavity are thermodynamically favoured over lateral or exterior host-guest interactions. The Infra-red (IR) spectroscopic vibrational signatures indicate the charge transfer which provide stability to the inclusion complexes. The smaller Egap values in CB[6-8]_NBD (where NBD is 7-nitrobenzo-2-oxa-1,3-diazole) compared to the simple CB[6-8] indicate kinetic control and reversible nature of inclusion complex formation in the former case. The sensing of cyclosarin is not possible through naked eye because the absorption and fluorescence spectra of CB[6-8]_cyclosarin complexes fall outside the visible region of wavelengths (380–750 nm). The NBD (7-nitrobenzo-2-oxa-1,3-diazole) fluorophore attached hosts CB[n]_NBD absorb and fluoresce in visible range (380–750 nm) on cyclosarin binding, thus making them important fluorescent sensors for cyclosarin and other CWAs.

LGB-Stack: Stacked Generalization with LightGBM for Highly Accurate Predictions of Polymer Bandgap.

Recently, the Ramprasad group reported a quantitative structure–property relationship (QSPR) model for predicting the Egap values of 4209 polymers, which yielded a test set R2 score of 0.90 and a test set root-mean-square error (RMSE) score of 0.44 at a train/test split ratio of 80/20. In this paper, we present a new QSPR model named LGB-Stack, which performs a two-level stacked generalization using the light gradient boosting machine. At level 1, multiple weak models are trained, and at level 2, they are combined into a strong final model. Four molecular fingerprints were generated from the simplified molecular input line entry system notations of the polymers. They were trimmed using recursive feature elimination and used as the initial input features for training the weak models. The output predictions of the weak models were used as the new input features for training the final model, which completes the LGB-Stack model training process. Our results show that the best test set R2 and the RMSE scores of LGB-Stack at the train/test split ratio of 80/20 were 0.92 and 0.41, respectively. The accuracy scores further improved to 0.94 and 0.34, respectively, when the train/test split ratio of 95/5 was used.