RESUMEN
The SARS-CoV-2 virus and its mutations have affected human health globally and created significant danger for the health of people all around the world. To cure this virus, the human Angiotensin Converting Enzyme-2 (ACE2) receptor, the SARS-CoV-2 main protease (Mpro), and spike proteins were found to be likely candidates for the synthesis of novel therapeutic drug. In the past, proteins were capable of engaging in interaction with a wide variety of ligands, including both manmade and plant-derived small molecules. Pyrus communis L., Ginko bibola, Carica papaya, Syrian rue, and Pimenta dioica were some of the plant species that were studied for their tendency to interact with SARS-CoV-2 main protease (Mpro) in this research project (6LU7). This scenario investigates the geometry, electronic, and thermodynamic properties computationally. Assessing the intermolecular forces of phytochemicals with the targets of the SARS-CoV-2 Mpro spike protein (SP) resulted in the recognition of a compound, kaempferol, as the most potent binding ligand, -7.7 kcal mol-1. Kaempferol interacted with ASP-187, CYS-145, SER-144, LEU 141, MET-165, and GLU-166 residues. Through additional molecular dynamic simulations, the stability of ligand-protein interactions was assessed for 100 ns. GLU-166 remained intact with 33% contact strength with phenolic OH group. We noted a change in torsional conformation, and the molecular dynamics simulation showed a potential variation in the range from 3.36 to 7.44 against a 45-50-degree angle rotation. SAR, pharmacokinetics, and drug-likeness characteristic investigations showed that kaempferol may be the suitable candidate to serve as a model for designing and developing new anti-COVID-19 medicines.
Asunto(s)
COVID-19 , Proteasas 3C de Coronavirus , Humanos , Animales , Cricetinae , Simulación del Acoplamiento Molecular , Quempferoles , Ligandos , Simulación de Dinámica Molecular , SARS-CoV-2 , Glicoproteína de la Espiga del Coronavirus , Mesocricetus , Inhibidores de ProteasasRESUMEN
In this study, for the first time, boron oxide nanoflake is analyzed as drug carrier for favipiravir using computational studies. The thermodynamic stability of the boron oxide and favipiravir justifies the strong interaction between both species. Four orientations are investigated for the interaction between the favipiravir and the B3O3 nanoflake. The Eint of the most stable orientation is -26.98 kcal/mol, whereas the counterpoise-corrected energy is -22.59 kcal/mol. Noncovalent interaction index (NCI) and quantum theory of atoms in molecules (QTAIM) analyses are performed to obtain insights about the behavior and the types of interactions that occur between B3O3 nanoflake and favipiravir. The results indicate the presence of hydrogen bonding between the hydrogen in the favipiravir and the oxygen in the B3O3 nanoflake in the most stable complex (FAV@B3O3-C1). The electronic properties are investigated through frontier molecular orbital analysis, dipole moments and chemical reactivity descriptors. These parameters showed the significant activity of B3O3 for favipiravir. NBO charge analysis transfer illustrated the charge transfer between the two species, and UV-VIS analysis confirmed the electronic excitation. Our work suggested a suitable drug carrier system for the antiviral drug favipiravir, which can be considered by the experimentalist for better drug delivery systems.
Asunto(s)
Compuestos de Boro , Teoría Cuántica , Teoría Funcional de la Densidad , Portadores de FármacosRESUMEN
Switchable nonlinear optical (NLO) materials have widespread applications in electronics and optoelectronics. Thermo-switches generate many times higher NLO responses as compared to photo-switches. Herein, we have investigated the geometric, electronic, and nonlinear optical properties of spiropyranes thermochromes via DFT methods. The stabilities of close and open isomers of selected spiropyranes are investigated through relative energies. Electronic properties are studied through frontier molecular orbitals (FMOs) analysis. The lower HOMO-LUMO energy gap and lower excitation energy are observed for open isomers of spiropyranes, which imparts the large first hyperpolarizability value. The delocalization of π-electrons, asymmetric distribution and elongated conjugation system are dominant factors for high hyperpolarizability values of open isomers. For deep understanding, we also analyzed the frequency-dependent hyperpolarizability and refractive index of considered thermochromes. The NLO response increased significantly with increasing frequency. Among all those compounds, the highest refractive index value is observed for the open isomer of the spiropyran 1 (1.99 × 10-17 cm2/W). Molecular absorption analysis confirmed the electronic excitation in the open isomers compared to closed isomers. The results show that reversible thermochromic compounds act as excellent NLO molecular switches and can be used to design advanced electronics.
RESUMEN
The interest in the NLO response of organic compounds is growing rapidly, due to the ease of synthesis, availability, and low loss. Here, in this study, Cu(II)-catalyzed selective N-arylation of 2-aminobenzimidazoles derivatives were achieved in the presence of different bases Et3N/TMEDA, solvents DCM/MeOH/H2O, and various aryl boronic acids under open atmospheric conditions. Two different copper-catalyzed pathways were selected for N-arylation in the presence of active nucleophilic sites, providing a unique tool for the preparation of NLO materials, C-NH (aryl) derivatives of 2-aminobenzimidazoles with protection and without protection of NH2 group. In addition to NMR analysis, all synthesized derivatives (1a-1f and 2a-2f) of 5-bromo-2-aminobenzimidazole (1) were computed for their non-linear optical (NLO) properties and reactivity descriptor parameters. Frontier molecular orbital (FMO) analysis was performed to get information about the electronic properties and reactivity of synthesized compounds.
RESUMEN
In the present study, 2-bromo-4-chlorophenyl-2-bromobutanoate (3) was synthesized via the reaction of 2-bromo-4-chlorophenol with 2-bromobutanoyl bromide in the presence of pyridine. A variety of 2-bromo-4-chlorophenyl-2-bromobutanoate derivatives (5a-f) were synthesized with moderate to good yields via a Pd-catalyzed Suzuki cross-coupling reaction. To find out the reactivity and electronic properties of the compounds, Frontier molecular orbital analysis, non-linear optical properties, and molecular electrostatic potential studies were performed.
Asunto(s)
Teoría Funcional de la Densidad , Hidrocarburos Halogenados/química , Paladio/química , Catálisis , Hidrocarburos Halogenados/síntesis química , Electricidad Estática , TermodinámicaRESUMEN
Nonlinear optical (NLO) switchable materials play a crucial role in the fields of electronics and optoelectronics. The selection of an appropriate switching approach is vital in designing such materials to enhance their NLO response. Among various approaches, thermos-switching materials have shown a 4-fold increase in NLO response compared to other photo-switching materials. In this study, we computationally investigated the geometric, electronic, and nonlinear optical properties of reversible lactone-based thermochromic compounds using the ωB97XD/6-311+G (d,p) level of theory. Molecular orbital studies are employed to analyze the electronic properties of the close and open isomers of these compounds, while time-dependent density functional theory (TD-DFT) analysis is utilized to evaluate their molecular absorption. Our findings reveal that the π-electronic conjugation-induced delocalization significantly influences the ON-OFF switchable nonlinear optical response of the lactone-based thermochromic compounds. Notably, among all compounds, the open isomer of lactone 2 exhibits the highest hyperpolarizability value (6596.69 au). Furthermore, we extended our analysis to investigate the frequency-dependent second and third-order hyperpolarizabilities. The most pronounced frequency-dependent NLO response is observed at 532 nm. Additionally, we calculated the refractive index of these thermochromic compounds to further assess their nonlinear optical response. The open isomer of lactone 1 demonstrates the highest refractive index value (3.99 × 10-14 cm2/W). Overall, our study highlights the excellent potential of reversible thermochromic compounds as NLO molecular thermos-switches for future applications.
Asunto(s)
Refractometría , Teoría Funcional de la DensidadRESUMEN
Ab initio calculations were performed to determine the sensing behavior of g-C3N4 and Li metal-doped g-C3N4 (Li/g-C3N4) quantum dots toward toxic compounds acetamide (AA), benzamide (BA), and their thio-analogues, namely, thioacetamide (TAA) and thiobenzamide (TAA). For optimization and interaction energies, the ωB97XD/6-31G(d,p) level of theory was used. Interaction energies (Eint) illustrate the high thermodynamic stabilities of the designed complexes due to the presence of the noncovalent interactions. The presence of electrostatic forces in some complexes is also observed. The observed trend of Eint in g-C3N4 complexes was BA > TAA > AA > TBA, while in Li/g-C3N4, the trend was BA > AA > TBA > TAA. The electronic properties were studied by frontier molecular orbital (FMO) and natural bond orbital analyses. According to FMO, lithium metal doping greatly enhanced the conductivity of the complexes by generating new HOMOs near the Fermi level. A significant amount of charge transfer was also observed in complexes, reflecting the increase in charge conductivity. NCI and QTAIM analyses evidenced the presence of significant noncovalent dispersion and electrostatic forces in Li/g-C3N4 and respective complexes. Charge decomposition analysis gave an idea of the transfer of charge density between quantum dots and analytes. Finally, TD-DFT explained the optical behavior of the reported complexes. The findings of this study suggested that both bare g-C3N4 and Li/g-C3N4 can effectively be used as atmospheric sensors having excellent adsorbing properties toward toxic analytes.
RESUMEN
In the pursuit of sustainable clean energy sources, the hydrogen evolution reaction (HER) has attained significant interest from the scientific community. Single-atom catalysts (SACs) are among the most promising candidates for future electrocatalysis because they possess high thermal stability, effective electrical conductivity, and excellent percentage atom utilization. In the present study, the applicability of late first-row transition metals (Fe-Zn) decorated on the magnesium oxide nanocage (TM@Mg12O12) as SACs for the HER has been studied, via density functional theory. The late first-row transition metals have been chosen as they have high abundance and are relatively low-cost. Among the studied systems, results show that the Fe@Mg12O12 SAC is the best candidate for catalyzing the HER reaction as it exhibits the lowest activation barrier for HER. Moreover, Fe@Mg12O12 shows high stability (Eint = -1.64 eV), which is essential in designing SACs to prevent aggregation of the metal. Furthermore, the results of the electronic properties' analysis showed that the HOMO-LUMO gap of the nanocage is decreased significantly upon doping of Fe (from 4.81 to 2.28 eV), indicating an increase in the conductivity of the system. This study highlights the potential application of the TM@nanocage SAC systems as effective HER catalysts.
RESUMEN
The designing of new materials having outstanding nonlinear optical (NLO) response is much needed for use in latest optics. Herein, the geometric, electronic and NLO properties of alkali and alkaline earth metals doped C6O6Li6 (alk-C6O6Li6-alkearth, alkearth = Ca, Mg, Be and alk = K, Na, Li) electrides is studied via quantum chemical approach. The interaction energies (Eint) are examined to illustrate their thermodynamic stability. The strong interaction energy of -39.99 kcal mol-1 is observed for Ca-C6O6Li6-Li electride in comparison to others. Frontier molecular orbitals (FMOs) energy gap of considered complexes is changed due to the electronic density shifting between metals and C6O6Li6 surface, which notifies the semi conducting properties of these electrides. The FMOs isodensities and natural bond orbital (NBO) charge analysis are performed to justify charge transfer between dopants and complexant. UV-Visible study also confirmed the application of these electrides as deep ultra-violet laser devices. NLO response is studied through calculation of first hyperpolarizability (ßo). The highest ßo value of 1.68 × 105 au is calculated for Mg-C6O6Li6-K electride. NLO response is further rationalized by three- and two-level models approach.
RESUMEN
A very fascinating aspect in quantum chemical research is to determine the accurate and cost-effective methods for the calculation of electronic and structural properties through a benchmark study. The current study focuses on the performance evaluation of density functional theory methods for the accurate measurement of bond dissociation energies (BDEs) of chemically important M-O2 bonds in water splitting reactions. The BDE measurement has got noteworthy attention due to its importance in all areas of chemistry. For BDE measurements of M-O2 bonds in five metal complexes with oxygen molecules, 14 density functionals (DFs) are chosen from seven classes of DFs with two series of mixed basis sets. A combination of pseudopotential and Pople basis sets [LANL2DZ & 6-31G(d) and SDD & 6-31+G(d)] are used as a series of mixed basis sets. The B3LYP-GD3BJ functional with LANL2DZ & 6-31G(d) gives outstanding results due to low deviations, error, and the best Pearson's correlation (R) between the experimental and theoretical data. Our study suggested an efficient, low-cost, precise, and accurate B3LYP-GD3BJ/LANL2DZ & 6-31G(d) level of theory for BDE of the M-O2 bond, which may be useful for chemists working in the field of energy generation and utilization.
RESUMEN
Herein, we examined the nonlinear optical properties of thia[7&8]circulenes (1-18). Circulenes are the building blocks of various nanomaterials such as graphene, nanotubes, and fullerenes. Many studies on circulenes have focused on the aromaticity of circulenes, but less attention has been paid on optoelectronics properties. Carbon atoms of the [7&8]circulenes are replaced with multiple sulfur atoms to designed thia[7&8]circulenes (1-18). These circulenes (1-18) are thermodynamically, kinetically, and chemically stable. Nonlinear optical (NLO) response is evaluated through static and frequency-dependent first and second hyperpolarizability values. The static first hyperpolarizability (ßo) of these compounds ranges between 0.00 and 496 au. The frequency-dependent coefficients for all thia[7&8]circulenes show remarkable enhancement at 532 and 1064 nm, respectively. The nonlinear refractive index is increased up to 1.13 × 10-14 au for circulene 9 at 532 nm. These findings successfully demonstrated that nonlinear optical response of thia[7&8]circulenes can be increased by decorating multiple sulfur atoms. The unsymmetrical distribution of sulfur atoms is more effective in enhancing nonlinear optical response.
RESUMEN
Bio-oils obtained from biomass contain heteroatoms compounds, like oxolane and thiolane. It is quite difficult for industrialist to purify such refractory bio-oils. One of the efficient strategies for the elimination of heteroatoms is hydrogenolysis process, which results in the formation of H2O and H2S residues as by-products. In this work, quantum chemical studies have been used to analyse the reaction mechanism for the removal of hetero atoms (S and O) as H2O and H2S. We selected B3LYP functional of DFT with Pople's basis set 6-311G(d,p) for computing the hydrogenolysis steps without catalyst. LANL2DZ basis set, is used for studying hydrogenolysis steps involving AlCl3 and WS3H3+ as catalysts. All the reactions are analysed at the temperature of 600 K and pressure of 40 bars. Structural, thermodynamic, kinetic properties have been employed to study this process. The analysis of variations parameters during the hydrogenolysis process reveals that these two organic biomass compounds undergo sequential ring opening at C-X (X = O, S) bonds. Butanol and Butanethiol are obtained as a result of first hydrogenolysis process, and these compounds are converted to butane during second catalytic process while eliminating heteroatoms.
Asunto(s)
Aceites , Biomasa , Catálisis , Cinética , TemperaturaRESUMEN
The geometric, electronic and nonlinear properties of exohedral and endohedral single and multiple alkali metal (Li, Na and K) atom doped C24 fullerene are studied. First, the most stable orientations at the most stable spin state are evaluated. Complexes with odd metal atoms are stable at doublet spin state and complexes with even number of metal atoms are stable at singlet spin state. Thermodynamic analysis shows that Li4C24 among all complexes with highest thermodynamic stability has interaction energy of -190.78 kcal mol-1. The energy gaps (GH-L) are fairly reduced in single and multi-doped cages, and the lowest energy gap is observed for K4C24 complex. NBO analysis is performed to validate the charge transfer from alkali metal toward C24. The largest amount of charge (0.95 |e|) transfer is monitored in exohedral K2C24 complex where the highest charge transfer is for potassium (K) metal. Total density of states (TDOS) spectra of doped complexes justify the involvement of alkali metals and nanocage in new HOMO formation for the excess electrons. First hyperpolarizability is descriptor of NLO properties of single and multi-doped complexes are calculated. It is observed that doping of alkali metal atoms (Li, Na and K) greatly enhances the first hyperpolarizability. Among all the complexes of C24, Na3C24 shows the highest hyperpolarizability value of 2.74 × 105 au. The results of this study are a guideline for the computational designing of highly efficient and thermodynamically stable complexes for the optical and optoelectronic technologies.
Asunto(s)
Fulerenos , Metales Alcalinos , Electrónica , Electrones , TermodinámicaRESUMEN
Herein, we present the detailed comparative study on geometric, electronic, optical and non-linear optical response of alkalis and superalkalis doped twisted graphene. The results illustrate that alkali metals and superalkalis interact with the central ring of the twisted graphene through non-covalent interactions which demonstrate the stability of the resultant complexes. NBO charges indicate the transfer of electrons from dopant (alkali metal atoms and superalkalis) towards twisted graphene sheet. Superalkalis doped twisted graphene complexes exhibit higher first hyperpolarizability values compared to alkali metals analogues. Among superalkalis doped complexes, K3O@C104H52 shows the highest ßo value of 1.68 × 105 au. In frequency dependent first hyperpolarizability analysis, strong second harmonic generation (SHG) response of K3O@C32H15 complex is observed at both selected resonance frequency values (532 nm and1064 nm) whereas EOPE value of K3O@C32H15 complex shows higher induced response at 1064 nm wavelength. The static hyperpolarizability (ßo) further increases under the influence of applied electric field. Among all complexes, Li3O@C32H15 graphene complex has the highest ßo value (1.40 × 105 au) under applied electric field along x axis when sheet is in y-z plane. This analysis will be an important guideline for future studies on twisted graphene based NLO materials.
Asunto(s)
Grafito , Teoría Cuántica , Álcalis , Electrones , VibraciónRESUMEN
In this report, the geometric and electronic properties and static and dynamic hyperpolarizabilities of alkali metal-doped C6O6Li6 organometallics are analyzed via density functional theory methods. The thermal stability of the considered complexes is examined through interaction energy (E int) calculations. Doping of alkali metal derives diffuse excess electrons, which generate the electride characteristics in the respective systems (electrons@complexant, e-@M@C6O6Li6, M = Li, Na, and K). The electronic density shifting is also supported by natural bond orbital charge analysis. These electrides are further investigated for their nonlinear optical (NLO) responses through static and dynamic hyperpolarizability analyses. The potassium-doped C6O6Li6 (K@C6O6Li6) complex has high values of second- (ßtot = 2.9 × 105 au) and third-order NLO responses (γtot = 1.6 × 108 au) along with a high refractive index at 1064 nm, indicating that the NLO response of the corresponding complex increases at a higher wavelength. UV-vis absorption analysis is used to confirm the electronic excitations, which occur from the metal toward C6O6Li6. We assume that these newly designed organometallic electrides can be used in optical and optoelectronic fields for achieving better second-harmonic-generation-based NLO materials.
RESUMEN
Based on DFT calculations, we have explored the changes in geometric, electronic and nonlinear optical (NLO) properties of M3O and M3S (M = Li, Na and K) doped graphdiyne. The doping of superalkalis not only changes the electronic properties of GDY but also remarkably alters the NLO properties. Stabilities of doped GDY are evaluated through interaction energies. HOMO-LUMO gap, NBO, polarizability and first hyperpolarizability (ßo) calculations at hybrid (B3LYP) and long-range corrected methods (CAM-B3LYP, LC-BLYP and ωB97XD) are performed for studying the NLO properties of doped GDY complexes. Significantly high values of ßo are observed for all doped structures, especially for Na3S@GDY (1.36×105 au). Reduction in HOMO-LUMO gap concomitant with increase of ßo value is attributed to the strong interaction of Na3S with GDY. The partial density of states (PDOS) spectra strongly support the existence of excess electrons. To rationalize the trends in first hyperpolarizability of doped GDY, two level model calculations are also performed. This study of super alkalis doped GDY will be advantageous for promoting the potential applications of the nanostructures in designing new types of electronic nanodevices and production of high performance nonlinear optical materials.
Asunto(s)
Electrónica , Electrones , Grafito , Modelos Moleculares , Conformación MolecularRESUMEN
Rapid electrocyclization is proposed under radical anionic conditions in organic photochromes. DFT calculations have been performed to investigate the radical anion mediated electrocyclization in different organic photochromes. Furthermore, the activation barriers under radical anionic conditions are compared with those in neutral and radical cationic conditions. The nuclear independent chemical shift (NICS(0)) and synchronicity calculations have been performed for the confirmation of concerted nature and aromatic character of transition states, respectively. The activation barrier for thermal return of cyclophanediene (CPD) to dihydropyrene (DHP) under radical anionic conditions is very lower (ΔH = 5.92 kcal/mol, ΔG = 6.97 kcal/mol) than under neutral conditions, but higher than that in radical cationic conditions (ΔH = 3.13 kcal/mol, ΔG = 4.0 kcal/mol). Similarly, the other prominent classes of photochromes; dithienylethene (ΔH = 20.12 kcal/mol, ΔG = 21.55 kcal/mol) and vinylheptafulvene (ΔH = 23.72 kcal/mol, ΔG = 24.82 kcal/mol) have shown decreased activation barrier under radical anionic condition. However, activation barrier of fulgide under radical anionic conditions is not different than those under neutral and radical cationic conditions. Synchronicity and NICS(0) values for organic photochromes also show significant changes under radical anionic conditions.
Asunto(s)
Termodinámica , AnionesRESUMEN
Nitriles are important chemical species in organic transformations, material chemistry, and environmental sciences. Nitriles are used as cyanating reagents in many organic reactions, where the C-CN bond dissociation has an important role. The reactivity of nitriles can be better understood by studying the bond dissociation energy (BDE) of the C-CN bond. In this benchmark study, homolytic cleavage of the C-CN bond in 12 nitrile compounds is studied. Thirty-one functionals from eight different DFT classes along with three types of basis sets are employed. Theoretical results are compared with the available experimental data. Based on statistical outcomes, the CAM-B3LYP functional of the range separated hybrid GGA class with Pople 6-311G(d,p) basis set provides the most accurate results for calculating the BDE of the C-CN bond. The mean absolute error (MAE) value is 0.06 kcal mol-1, whereas standard deviation (SD) and Pearson's correlation (R) are 2.79 kcal mol-1 and 0.96, respectively, when compared with experimental data. The substitutional effect on the homolytic cleavage (BDE) of respective bonds in differently substituted nitriles is also investigated. The BDE results indicate that electron withdrawing groups (EWGs) lower the BDE, while electron donating groups (EDGs) increase the BDE of the C-CN bond. The NBO and HOMO-LUMO orbitals analyses are also performed to further elaborate the variational BDE patterns of C-CN bond cleavage. Graphical Abstract Benchmark DFT studies on C-CN homolytic cleavage.
RESUMEN
Density functional theory calculations are performed to evaluate the sensing ability of polypyrrole for oxynitrogen analytes. Interaction energies of PPy-X (X = NO2-, NO2, and NO) are calculated at B3LYP-CP/6-31G(d) and B3LYP/6-31G(d) levels of theory and compared with the high level calibrated method (M05-2X/aug-cc-pVDZ). B3LYP-CP/6-31G(d) gives the best correlation with the high level calibrated method compared to B3LYP/6-31G(d). Interaction of oligopyrrole with analytes shows a significant effect on the geometric and electronic properties; the conjugation is increased in the pyrrole oligomers and movement of charge is increased over the polymeric backbone. The charge is transferred from analytes to pyrrole oligomers (except nPy-NO2), and a more pronounced effect of charge transfer is observed in the case of nitrite ion (NO2-) compared to NO. In nPy-NO2, the charge is transferred from polymer to analyte. This transfer of charge indicates the n-type doping effect of analytes. The HOMO-LUMO gap decreases after interaction with analytes, which results in a drop of resistance (conductivity increases). These theoretical outcomes are consistent with the experimental results; polypyrrole has more sensing ability toward the nitrite anion (NO2-). Graphical abstract High sensitivity of polypyrrole towards NO over NO2 and NO2.
RESUMEN
In our effort directed toward the discovery of new anti-diabetic agent for the treatment of diabetes, a library of biscoumarin derivative 1-18 was synthesized and evaluated for α-glucosidase inhibitory potential. All eighteen (18) compounds displayed assorted α-glucosidase activity with IC50 values 16.5-385.9 µM, if compared with the standard acarbose (IC50 = 906 ± 6.387 µM). In addition, molecular docking studies were carried out to explore the binding interactions of biscoumarin derivatives with the enzyme. This study has identified a new class of potent α-glucosidase inhibitors.