Heteroatom Research Articles

Tautomerism and nucleophilic addition influence the performance of aqueous organic redox flow batteries of chelidamic acid and chelidonic acid

The influence of tautomerism and nucleophilic addition on chelidamic acid and chelidonic acid, compounds with similar molecular weights but different hetero atoms, was investigated in aqueous organic redox flow batteries.

A theoretical investigation on the OER and ORR activity of graphene-based TM-N3 and TM-N2X (X = B, C, O, P) single atom catalysts by density functional theory calculations.

Single-atom catalysts (SACs) have shown promising activity in electrocatalysis, such as CO2 reduction (CO2RR), the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR). Transition-metal-embedded N-doped graphene (M-N-C) with TM-N4 active sites (where TM represents a transition metal) is a representative SAC family that has attracted the most attention in both experimental and theoretical studies. However, TM-N3 type M-N-C has received less attention than TM-N4, although some experimental studies have reported its excellent activity in OER and CO2RR. To fully explore the electrocatalytic activity of TM-N3 type M-N-C, in this work we systematically investigate the OER and ORR activity of TM-N3 (TM = Ti, V, Cr, Mn, Fe, Co, Ni, Cu) and TM-N2X (X = B, C, O, P) using density functional theory (DFT) calculation. We examine the formation energies, OER/ORR free energy diagrams, overpotentials, charge density, d-band center and electronic structure of each candidate. Our computational screening shows that CuN3 is a promising bifunctional electrocatalyst for both OER and ORR with low overpotentials of 0.31 V (OER) and 0.44 V (ORR), while CrN3 and CuN2B are predicted to be promising OER catalysts, with overpotentials of 0.26 V and 0.50 V, respectively. A volcano plot derived from the scaling relationships suggests that substituting one nitrogen atom with a hetero atom significantly affects the potential-limiting step in OER/ORR, leading to worse activity in most cases. Density of states and d-band center analyses indicate that the change in OER/ORR activity is strongly correlated with the binding strength of *OH, which is dominated by the location of the d-band center. Our simulation results introduce a comprehensive insight into the activity of the TM-N3 site in TM-N-C, which could benefit the further development of graphene-based SACs for fuel cells and renewable energy applications.

Enzymatic S‐Methylation of Thiols Catalyzed by Different O‐Methyltransferases

AbstractS‐Adenosyl‐l‐methionine (SAM)‐dependent methyltransferases (MTs) are highly chemoselective enzymes grouped in C‐, N‐, O‐, S‐ and halide MTs, depending on the (hetero) atom that acts as the methyl group acceptor. So far, OMTs present the largest group, including many well investigated candidates. The catechol OMT from mammals such as from Rattus norvegicus (RnCOMT) is involved in the metabolism of neurotransmitters like dopamine. It is known to methylate the hydroxyl of the catechol ring in the 3 position. There are also reports showing that the regioselectivity of different COMTs can vary leading to different products with methyl groups in the 3 and or 4 positions. Nevertheless, there was only O‐methylation reported for COMTs. Another related MT, the caffeate OMT involved in the lignin biosynthesis of plants has also been reported as a chemoselective enzyme. In nature, S‐methylation is a rare phenomenon with different methyl donors being involved in the methyl transfer onto sulfur atoms. Several SAM‐dependent MTs are identified as S‐methyltransferases (SMTs), these are involved in salvaging pathways and xenobiotic metabolism of cells. Here, we report a new function of three OMTs; RnCOMT, a COMT from Myxococcus xanthus (MxSafC), and a CaOMT from Prunus persica (PpCaOMT) with acceptance towards different aromatic thiol substrates with up to full conversion.

Construction of defective surface structure via hetero atoms (N, S) implantation into waste cypress biomass-derived catalysts for efficient hydrogen evolution reaction

Developing highly efficient hydrogen evolution catalysts with low cost has been a big challenge in industrial applications. Herein, we developed non-metallic heteroatoms doped waste cypress biomass-derived biochar via a facile one-step pyrolysis route. By utilizing defect engineering and charge carriers facilitation, we have constructed appropriated defects with numerous charge carriers for manufacturing efficient catalysts for Hydrogen Evolution Reaction (HER). Through N(0.75), S(0.25)-CBC, we attained a low over-potential value of 122 mV at the current density of 10 mA cm−2 and minimized the Tafel slope value of 112 mV dec−1 in 1 M KOH solution for HER. Furthermore, it attained robust chemical stability of over 50,000 s without any degradation. Hence, this work provides a practical pathway to synthesize cost-effective, non-metallic heteroatoms doped efficient catalysts for hydrogen generation.

Heterogeneous single-atom doped 2D-layered graphitic carbon nitride electrocatalyst for oxygen evolution reaction and removal of toxic heavy metal ion Cr from Wastewater

The 2D-layered graphitic carbon nitride (gCN) has been a well-known electro-photocatalyst to have wide applications in energy storage, energy evolution, and environmental remediation. The physicochemical properties of the bulk, O-doped (O-gCN), and hetero atom are compared, which is further utilized as an electrocatalyst for the oxygen evolution reactions (OER) process. The prepared nanosheets exhibited a layered structure with a uniform porous nature. Moreover, the forbidden energy bandgap (Eg) of 1.7 eV is observed, which is lower than bulk and O-doped gCN. The heteroatom BO-gCN nanosheets have higher OER activity compared to other samples and benchmark catalysts. The BO-gCN nanosheets exhibit a lower overpotential and Tafel potential of 240 mV and 207 mV/dec, respectively. Effects of various operating parameters such as photocatalyst dosage and solution pH are investigated. The photocatalytic removal results exhibited BO-gCN can be a robust and effective catalyst for the removal of Cr ions in environmental remediation.

Experimental and computational insight into the role of cobalt and phosphorus in boosting Volmer and Heyrovsky steps of Ni in alkaline hydrogen evolution reaction

Deep insight into the role of doped hetero atoms in boosting the alkaline hydrogen evolution reaction (HER) activity is of significance for designing the low-cost electrocatalysts to produce hydrogen. Herein, we designed, synthesized, and optimized the Co and P co-doped Ni (NCP) electrocatalysts and evaluated the HER performance in alkaline medium. It was found that the NCP exhibited the enhanced hydrogen evolution performance, only need an overpotential of 57.0 mV to afford 10 mA·cm−2. The calculation results of density functional density revealed that the doped P plays an important role in modulating electron distribution of Ni and Co atoms, which reduce the Gibbs free energy of water molecule dissociation at Co sites in Volmer step, and optimize the ab/desorption of hydrogen at Ni site that bonded to P and Ni atoms in Heyrovsky step, respectively. The obtained results are conductive to understanding the electrocatalytic mechanism of alkaline HER.

Synthesis and cytotoxic activity evaluation of 1,4-dihydropyridine derivatives using Ag2O/GO/TiO2 composite nanostructure

Ag2O/GO/TiO2 composite nanostructure was established as a heterogeneous catalyst for the one pot synthesis of dihydropyridine derivatives via Hantzsch reaction. The synthetic method was mainly used in the presence of Ag2O/GO/TiO2 nano composite as a heterogeneous solid catalyst. This nano composite catalyzed Hantzsch reaction afforded good yields (87–95%) in solvent free condition at 90 °C. A broad range of structurally diverse aldehydes were applied successfully, and corresponding products were obtained in high yields without any byproduct. Compared with other methods, satisfactory results are obtained with high yields, short reaction times, and simplicity in the experimental procedure. Cytotoxic activities for some of the synthesized compounds were evaluated by MTT assay in three human cancer cell lines (HeLa, LS180 and Raji). Half of the tested compounds showed good cytotoxicity in Raji cells. Diethyl 4-(2,4-dichlorophenyl)-1,4-dihydro-2,6-dimethylpyridine-3,5-dicarboxylate (3 i) was found to be the most potent molecule among the studied 1, 4 dihydropyridines derivatives. Electron withdrawing groups along with heterocyclic rings bearing more hetero atoms seemed to be necessary factors in providing higher cytotoxic activities in Raji cell lines.

Updates on the Synthetic Strategies and Structure-Activity Relationship of Anticonvulsant Benzothiazole and Benzimidazole Derivatives

Abstract: Epilepsy is a chronic neurological disorder characterized by periodic and unpredictable seizures affecting the neurobiological, psychological, cognitive, economic, and social well-being of patients. It is one of the causes of concern in developed as well as developing countries as currently marketed drugs are not capable of providing protection against it. Although several heterocyclic moieties have been frequently used as building blocks for the preparation of anticonvulsant drugs, more focused and consistent research on the synthesis of potential molecules with less adverse effects is the need of the hour. It can be concluded on the basis of available research reports that among several heterocyclic compounds, benzo-fused five-membered heterocyclic moieties (benzothiazole and benzimidazole) have been utilized far less than their great potential as building blocks for the synthesis of anticonvulsant drugs. Various reports clearly established that the required pharmacophore model could be easily achieved through benzothiazole and benzimidazole moieties as two hetero atoms and aryl rings are present in the structure. The present study highlights various synthetic approaches for anticonvulsant benzothiazole and benzimidazole derivatives with their structure-activity relationship studies in order to provide a trove of knowledge to medicinal chemists for future research.

A Novel Quasi-Planar Two-dimensional Carbon Sulfide with Negative Poisson's ratio and Dirac fermions.

In the present study, a novel and unconventional two-dimensional (2D) material with Dirac electronic features hasbeen designed using sulflower with the help of density functional theory methods and first principles calculations.This 2D material comprises of hetero atoms (C, S) and belongs to the tetragonal lattice with P4/nmm space group. Scrutiny of the results show that the 2D sheet exhibits a nanoporous wave-like geometrical structure. Quantummolecular dynamics simulations and phonon mode analysis emphasize the dynamical and thermal stability. Thenovel 2D sheet is an auxetic material with an anisotropy in the in-plane mechanical properties. Both compositionand geometrical features are completely different from the necessary conditions for the formation of Dirac conesin graphene. However, the presence of semi-metallic nature, linear band dispersion relation, massive fermions andmassless Dirac fermions are observed in the novel 2D sheet. The massless Dirac fermions exhibit highly isotropicFermi velocities (vf = 0.71 × 106 m/s) along all crystallographic directions. The zero-band gap semi metallic featuresof the novel 2D sheet are perturbative to the electric field and external strain.

BN-bicyclohexyl material for enhanced reversible dehydrogenation reaction for hydrogen storage: Density functional theory approach

Hydrogen is considered as an environmentally friendly energy resource to replace fossil fuels. This study aims to enhance the dehydrogenation efficiency of liquid organic hydrogen carrier (LOHC) materials by investigating the dehydrogenation and hydrogenation mechanisms through hetero atom (B and N) substitution of bicyclohexyl, as well as by applying the high-efficiency catalysts, palladium and ruthenium. To achieve this, BN-bicyclohexyl, a novel material based on bicyclohexyl, was proposed using density functional theory (DFT) calculations, and the synthesis of the new material was evaluated through enthalpy and free energy calculations. Mulliken charge analysis showed that the B and N atoms substituted in bicyclohexyl can induce dihydrogen bonding, resulting in efficient dehydrogenation at the substitution site. The dehydrogenation efficiency of BN-bicyclohexyl (1.53 eV in activation energy) surpasses that of bicyclohexyl (2.77 eV) on the Pd(111) surface. However, on the Ru(001) surface, BN-bicyclohexyl exhibits a slightly lower hydrogenation efficiency than bicyclohexyl, with an increase of 0.39 eV in activation energy. This trend highlights BN as a promising candidate for enhancing the capability of LOHCs. Notably, the dehydrogenation efficiency of BN-bicyclohexyl is significantly higher than that of bicyclohexyl, which go beyond slightly lower hydrogenation efficiency than bicyclohexyl.

Charge Transfer and Optical Characteristics of cyclopenta-diene based Oligomers

1,4-bis(2-(cyclopenta-1,3-dien-1-yl)ethyl)cyclopenta-1,3-diene [CCD] is one of the interesting oligomer with high charge carrier mobility and chemical stability. Based on the density functional theory (DFT), the electronic characteristics of four CCD molecules with various hetero atom substituents are investigated. The electronic of four CCD molecules with different hetero atom substituents are explored based on the density functional theory (DFT). The effects of substituents on the molecular structure, molecular orbitals, ionization energies, electron affinities, reorganization energy and crystal packing are analysed in detail to clarify the structure-property relationship of the studied molecules. The different crystal packing arrangements and intermolecular interactions of the studied molecules lead to differences in transfer integrals when introducing different substituents to the CCD molecule.

Influences analysis of Sb/Si dopant in TiO2 on NH3-SCR activity and low temperature SO2 resistance of V2O5/TiO2 catalysts

The Sb/Si doped TiO2 prepared by sol–gel method were used as supports of V2O5/TiO2 SCR catalysts in order to improve SCR activity and SO2 resistance. The type of dopant atoms changed catalyst physiochemical properties discriminatively. Surface chemical properties of catalysts played more important role in their catalytic performance. Simultaneous enhanced surface acidity and redox capacity leaded to the better SCR activity for V2O5/Sb-TiO2 compared with other catalysts. The low temperature SO2 resistance was improved for the support doped catalysts. The special electronic charge migration brought by surface sulfate species for V2O5/Sb-TiO2 even elevated its SCR activity during SO2 resistance test, which was due to the formation of new acid sites and enhancement of redox performance. Even though NOx conversion for V2O5/Si-TiO2 decreased, the relative stable efficiency was kept at low temperatures with SO2. The results proved hetero atom doping in TiO2 by sol–gel method was a useful method to improve low temperature SO2 resistance of catalysts. By contrast, Sb is a better choice for the development of support doped V2O5/TiO2 SCR catalyst used in a wide temperature range.

C−H Functionalized Molecules: Synthesis, Reaction Mechanism, and Biological Activity

AbstractReplacement of traditionally unreactive C−H bond with C−C or C−X (X=Hetero atom) has emerged as one of the widely accepted methods over the last few decades for the synthesis of complex organic molecules which can act as important intermediates for the synthesis of biologically active compounds. Selective functionalization of the C−H bond especially in the presence of a more reactive C−H bond has remained one of the biggest challenges for synthetic organic chemists. The hybridization state of the C−H bond, substitution pattern, and presence of directive groups are some of the factors which have been exploited by researchers over the years for achieving fruitful results. A considerable amount of work has been reported in the literature on the use of metal catalysts for C−H bond functionalization leading to the formation of a C−M (carbon‐metal) bond which is also known as C−H bond activation. This review aims to summarize various synthetic strategies reported for the C−H functionalization, which has led to the development of targeted complex molecules with medicinal properties.

General cross-coupling reactions with adaptive dynamic homogeneous catalysis.

Cross-coupling reactions are among the most important transformations in modern organic synthesis1-3. Although the range of reported (het)aryl halides and nucleophile coupling partners is very large considering various protocols, the reaction conditions vary considerably between compound classes, necessitating renewed case-by-case optimization of the reaction conditions4. Here we introduce adaptive dynamic homogeneous catalysis (AD-HoC) with nickel under visible-light-driven redox reaction conditions for general C(sp2)-(hetero)atom coupling reactions. The self-adjustive nature of the catalytic system allowed the simple classification of dozens of various classes of nucleophiles in cross-coupling reactions. This is synthetically demonstrated in nine different bond-forming reactions (in this case, C(sp2)-S, Se, N, P, B, O, C(sp3, sp2, sp), Si, Cl) with hundreds of synthetic examples under predictable reaction conditions. The catalytic reaction centre(s) and conditions differ from one another by the added nucleophile, or if required, a commercially available inexpensive amine base.

An Evulative Study on Different Methods of Multi-component Synthesis on Heterocyclic Compounds

Heterocyclic compounds have a significant role in our daily lives. These compounds make up the biggest and most diverse organic compound family. Heterocyclic compounds have one or more hetero atoms in their molecular structure. The number of heterocyclic compounds is growing fast as a result of extensive synthetic research and their usefulness in synthetic chemistry. They might be cyclic or acyclic. Primarily, they are utilized as medications, agrochemicals, and veterinary goods. In addition, they are used as sanitizers, developers, antioxidants, corrosion inhibitors, copolymers, coloring agents, and anticancer medicines. They are utilized as vehicles in the synthesis of other organic molecules. In this article, we discuss the majority of newly synthesized or extracted biologically active heterocyclic compounds, such as antibiotics like penicillin and cephalosporin and alkaloids like vinblastine, morphine, and reserpine.

ANTIMICROBIAL ACTIVITY OF ORGANIC NLO CRYSTALS USING THIOSEMICARBAZONE DERIVATIVE

Thiosemiccarbozones are having enormous medicine applications due to the presence of hetero atom nitrogen and sulfur in its molecular structure. The carbonyl compounds are also having the largest clinical applications to cure many diseases. We merged these two classes of organic compounds and their substitution by solution growth techniques of crystal growth tested as antibiotic against few fastidious and non fastidious gram +ve and gram –ve organisms. Ortho substituted para substituted and Meta substituted benzaldehydes were merged with thiosemicarbazone and prepared. Thiosemicarbazone of (2-chlorophenyl) methylideneamino thiourea, when compared with linear optical material, these NLO have high medicinal application since it is the photo dynamic therapeutically more active, proved by the early researches mentioned in the experimental part. These one compounds were tested against. Streptococcus Aureus, the following experimental method was adopted find out the antimicrobial activity. MTT assay by colorimetric method, Cell viability percentage calculation method, Half inhibitory maximum (IC50) by calculation method. Agar disc diffusion method. Inhibition zone width by agar disc diffusion method, EUCAST and NCCLS database analysis to compare the MIC and inhibition zone width of existing antibiotic against the above said one organism, Graphpad prism software is used to find out the absolute, relative IC50 value and hill slope value, ECOF finder software to find out the epidemiology cutoff value, WHONET 5.6 software analysis is used to find out resistant, susceptible or intermediate nature of commercially existing antibiotics. Size and structure of the newly designed antibiotics compare with the structure of commercially existing antibiotics and structure of organisms. KEYWORDS: MTT Assay, Cell Viability, IC 50, Agar Dis Diffusion, Graph pad ,EcoF Finder, EUCAST,NCCLS.

Corrosion resistance of Aluminium steel in 1N Sodium Hydroxide solution by an aqueous extract of Thespesia populnea plant leaves

Corrosion resistance effect of aluminium steel in 1N sodium hydroxide by an aqueous extract of Thespesia populnea plant leaves has been investigated by mass loss method. It is observed that as the concentration of the inhibitor increases, the inhibition efficiency increases. The mechanistic aspects of corrosion resistance have been studied by potentiodynamic polarization technique and electrochemical impedance spectroscopy. A maximum inhibition efficiency of 78.70% is achieved by this inhibitor system. Potentiodynamic polarization technique reveals that the inhibitor system functions as a mixed type of inhibitor, controlling anodic and cathodic reactions. It is noted that in the presence of inhibitor, linear polarization resistance value increases and corrosion current decreases. Electrochemical impedance studies reveal that a protective film is formed on the Al steel surface, since in the presence of inhibitor system, the charge transfer resistance value increases and double layer capacitance value decreases. This is due to adsorption of the molecules of the active ingredients of the extract on the Al steel surface. The inhibition efficiency increases due to adsorption of hetero atoms present in TP plant leaves extract on the Al steel surface. The maximum inhibition efficiency and the lower corrosion rate are obtained at high concentration 1200 ppm for TP plant leaves extract. By further increase in inhibitor concentration above 1200 ppm, the inhibition efficiency and corrosion rate almost remained constant. So, the 1200 ppm concentration is fixed as the maximum inhibition for the investigative aqueous extract of plant leaves as corrosion inhibitor. This concentration corresponds to the attainment of a saturation value in surface coverage of Al steel. The protective film formed over the Al steel surface has been characterized by Fourier Transform infra-red spectroscopy. The surface morphology of the protective film of carbon steel immersed in sodium hydroxide in the absence and presence of inhibitor has been studied by Scanning electron microscopy. The outcome of the study can be used in pickling industry wherein sodium hydroxide is used to remove the rust on the Al steel surface.

Investigating multifaceted action of ibuprofen derivatives towards cox isozymes and interleukin-6 (IL-6) site correlating with various target sites

The multifaceted action of new ibuprofen analogs has been investigated against inflammation, neurological and pro-inflammation factors. On the basis of ADMET (absorption, distribution, metabolism, excretion, and toxicity) analysis, molecular docking as well as molecular dynamics simulation, compound 3 was thought to have good anti-inflammatory activity. As the presence of structural interactions such as conventional hydrogen bonds and electrostatic interactions through the nitrogen atoms of the linker in compound 3 gave strong evidence of its potency. The major finding of the current work is that the presence of appropriate number of hetero atoms (NH, OH) in a compound makes it more efficient than the number of labile groups (i.e., hydroxyl groups). Additionally, the position of hetero atoms in a compound and orientation also play a vital role in its efficacy. It was also screened for in vitro anti-inflammatory activity by membrane stability method, where it has shown 90.8% protection of RBC hemolysis. Thus, compound 3 with effective structural features may have good anti-inflammatory activity. Communicated by Ramaswamy H. Sarma

Efficient overall water-splitting enabled by tunable electronic states of vanadium-substituted P–Co3O4

Despite the fact that phosphorus (P) partly substituted Co3O4 (P–Co3O4) has been considered as an intriguing electrocatalyst toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), the modulation of electronic property using hetero atoms to improve activities of P-rich Co3O4 catalyst remains an elusive goal. Herein, we demonstrate that the vanadium (V) doping provides the most promising strategy to significantly regulate the electronic states of P–Co3O4, thus yielding an outstanding overall water-splitting performance. A small cell voltage of 1.594 V is required to deliver the current density of 10 mA/cm2, largely outperforming the RuO2||Pt/C catalyst. It is further revealed that the added V5+ with empty 3d orbital can act as electron acceptors, which weakens the coordination of Co–O band. As a result, the electrons are inclined to transfer to the V through the O ligand, rather than to Co. We then report that the V doping could modulate the local electronic configuration and atomic arrangement of bonded Co and adjacent O atoms to enhance the electrons’ delocalization capacity of Co atoms for high electrical conductivity, as well as effectively accelerate the formation of key H∗ intermediates toward fast HER kinetics. These findings represent a new strategy for regulating the electronic properties of catalysts and are expected to open new opportunities for the development of high-performance catalysts.

Expeditious microwave assisted green synthesis of phosphorous doped carbon obtained from Mangifera Indica for adsorptive desulfurization of fuel

Carbon based adsorbent material with Phosphorus doping was synthesized from natural source with microwave assistance. The Oxidative desulfurization of model fuel (Dibenzothiophene in n-hexane) was carried out through ultrasonication with the prepared adsorbent. Comparison of hetero atom doping ratio on the natural material with respect to the adsorption efficiency of sulfur was characterized thoroughly before and after adsorption using techniques such as FT-IR, Raman, XRD, XRF, TGA, XPS and SEM-EDS analysis. BET-N2 isotherm revealed the mesoporous nature of the material with high specific surface area of 390.17 m2 g−1 which gave a high adsorption capacity of 64.1 mg g−1 for Dibenzothiophene (DBT). The overall mechanistic features were corroborated through isotherm, kinetic and thermodynamic data wherein it was found that the reaction follows pseudo-first order kinetics and the overall process is an endothermic reaction being spontaneous and feasible. The material was tested for removal of sulfur from the commercial diesel where it was capable of removing 66 % sulfur content from the commercial diesel. The regeneration and reproducibility studies showed that the adsorbent gave maximum efficiency till six cycles when n-pentane was used to desorb the DBT.