DFT investigation of adsorption of nitro-explosives over C2N surface: Highly selective towards trinitro benzene

Organotin(IV) derivatives of 4-chloro-2-methylphenoxyacetic acid: synthesis, spectral characterization, X-ray structures, anticancer, enzyme inhibition, antileishmanial, antimicrobial and antioxidant activities

Four organotin(IV) carboxylate complexes; (C4H9)3SnL (1), CH3SnL (2), (C4H9)2SnL2 (3) and (CH3)2SnL2 (4) are synthesized by the condensation reaction of organotin(IV) chlorides with sodium-4-chloro-2-methylphenoxyacetate (NaL). The FT-IR spectra suggested bridging/chelating bidentate coordination of the ligand to the tin atom. Single-crystal XRD analysis authenticated the FT-IR findings for 1 and 2. The NMR study has shown no significant differences in the signals of the free and coordinated ligand except for absence of a proton and up-filed/down-field shift of the C signal of the carboxyl group in the spectra. Complexes 1-4 have shown better enzyme inhibition, antioxidant, antimicrobial, and anticancer activities compared to the free ligand acid. Complex 3 was the most active inhibitor of AChE, BChE, α-glucosidase and α-amylase with IC50 values of 43.76, 102.39, 232.71 and 91.84 µg/mL, respectively. Additionally, 3 with IC50 values of 7.52 and 8.77 µg/mL in the DPPH and ABTS assays, respectively was better antioxidant than the standard. Complex 4 was the most efficient inhibitor of MAO-B and COX-2 enzymes with IC50 values of 106.99 and 12.98 µg/mL, respectively, while 1 (IC50 = 38.97 µg/mL) has shown the highest 5-LOX inhibition potential. Complexes 1-4 with IC50 values in the range 237.51-168.35 µg/mL have shown better antileishmanial activity than HL (IC50 = 277.57 µg/mL). The compounds showed good to potent antiproliferative activity in malignant glioma U87 cells with IC50 values in the range 12.54 ± 0.05 to 37.65 ± 0.04 µg/mL. Antimicrobial activities have shown promising results for the compounds compared to the standards in some cases.

Chiral recognition of amino acids through homochiral metallacycle [ZnCl2L]2

Chiral recognition holds tremendous significance in both life science and chemistry. The ability to differentiate between enantiomers is crucial because one enantiomer typically holds greater biological relevance while its counterpart is often not only unnecessary but also potentially harmful. In this regard, homochiral metallacycle [ZnCl2L]2 is used in this study to understand and differentiate between the R and S enantiomers of amino acids (alanine, proline, serine, and valine). The electronic, geometric, and thermodynamic stabilities of the amino acid enantiomers inside the metallacycle are determined through various analyses. The greater interaction energy (Eint) is obtained for the ser@metallacycle complexes i.e., -33.03 and -30.75 kcal mol-1, respectively for the S and R enantiomers. The highest chiral discrimination energy of 3.11 kcal mol-1 is achieved for ala@metallacycle complexes. Regarding the electronic properties, the frontier molecular orbital (FMO) analysis indicates that the energy gap decreases after complexation, which is confirmed through density of states (DOS) analysis. Moreover, natural bond orbital (NBO) analysis determines the amount and direction of charge transfer i.e., from metallacycle towards amino acids. The maximum NBO charge transfer is observed for S-pro@metallacycle complex i.e., -0.291 |e|. Electron density difference (EDD) analysis further proves the direction of charge transfer. Noncovalent interaction index (NCI) and quantum theory of atoms in molecules (QTAIM) analyses demonstrate that the noncovalent interactions present between the host and guest are the weak van der Waals forces and hydrogen bonding. The results of NCI and QTAIM analyses for all the complexes are in alignment with those of the interaction energy (Eint) and chiral discrimination energy (Echir) analyses, i.e., significantly greater non-bonding interactions are observed for the complexes with greater Echir, i.e., for ala@metallacycle. Overall, our analyses demonstrate the excellent chiral discrimination ability of metallacycle towards chiral molecules, i.e., for enantiomers of amino acids through host-guest supramolecular chemistry.

External surface hydrophilic 3D-POSS-COF@GDL for the direct adsorption of bisphenols in milk samples

In case of organic frameworks (COFs) as adsorbents in the pretreatment of complex food matrices, challenges such as poor dispersion and non-specific adsorption of interfering macromolecules like proteins are often encountered. To address this issue, this work prepared a three-dimensional covalent organic framework (3D-COF) with a novel bcu topology based on polyhedral oligomeric silsesquioxane (POSS). Subsequently, gluconolactone (GDL) was modified onto the external surface of the material via the reaction with the exposed reactive residues. The resulting POSS-COF@GDL adsorbent has an enhanced hydrophilicity in the external surface, thereby significantly improves the dispersion of materials in aqueous solution and reduces the adsorption ability toward protein. Whereas, the inner of material retains hydrophobic pores that exhibit high adsorption efficiency to small hydrophobic molecules. Compared with the traditional pretreatment methods, POSS-COF@GDL can directly extract bisphenols (BPs) in milk samples without any additional treatment. The established sample pretreatment method is coupled with high-performance liquid chromatography-ultraviolet detection (HPLC-UV), resulting in recoveries of 71.8 to 93.6%, intra- and inter-day relative standard deviations (RSDs) of <8.3%, and limits of detection (LODs) of 0.042-0.16 ng∙mL-1 for four BPs.

CO2 capturing by self-assembled belt[14]pyridine encapsulated ionic liquid complexes: a DFT study

In the current study, CO2 capturing ability of encapsulated ionic liquids (ENILs) i.e., tetramethylammonium chloride (TMACl), 1,3-dimethylimidazolium chloride (MIMCl), and methylpyridinium hexafluorophosphate (MPHP) encapsulated in self assembled belt[14]pyridine (BP) has been studied. The results show that strong van der Waals forces are involved in capturing of CO2 by these encapsulated ionic liquids. Strong attractive forces arise from synergistic effect of ionic liquid (encapsulated) and atoms of belt. The interaction energies (E int) ranging from -12.54 to -18.64 kcal mol-1 reveal the capturing of CO2 by these systems as thermodynamically feasible process. The type and strength of interactions between CO2 and encapsulated ionic liquids is studied through QTAIM and NCI analyses. NCI analysis clearly shows that capturing of CO2 is assisted by van der Waals forces between CO2 and encapsulated ionic liquid complexes. The same feature is confirmed through QTAIM analysis as well. Natural bond orbital (NBO) analysis' results show the charge transfer between the fragments (encapsulated ionic liquids and CO2) which is validated further through electron density differences (EDD) analysis. Overall, transfer of charge towards CO2 from encapsulated ionic liquids is proved through the charge accumulation over CO2 (i.e., blue isosurfaces on CO2 molecules) through EDD analysis. The FMO analyses show the decrease in H-L gaps of encapsulated ionic liquids after CO2 capturing. The successful charge transfer and reduction in H-L gap indicate better interaction in the designed systems thus revealing these systems as a potential candidates for CO2 capturing. Overall, the best results for CO2 capture i.e., the highest interaction energy, the lowest H-L gap, and the strongest forces of interactions are shown by methylpyridinium hexafluorophosphate (MPHP) encapsulated belt[14]pyridine (BP-MPHP) system. This is due to the larger anion of methylpyridinium hexafluorophosphate as compared to the other two encapsulated ionic liquids with Cl- as anion which enables it to develop strong interactions with CO2. The designed belt[14]pyridine based encapsulated ionic liquid systems are promising prospects with better CO2 capture performance and represent a new entrant in the CO2 capturing systems.

Detection of nitro-aromatics using C5N2 as an electrochemical sensor: a DFT approach

Nitroaromatics impose severe health problems and threats to the environment. Therefore, the detection of such hazardous substances is essential to save the whole ecosystem. Herein, the C5N2 sheet is used as an electrochemical sensor for the detection of 1,3-dinitrobenzene (1,3-DNB), trinitrotoluene (TNT), and picric acid (PA) using the PBE0/def2SVP level of theory as implemented in Gaussian 16. The highest interaction energy was observed for the picric acid@C5N2 complex. The trend in interaction energies for the studied system is PA@C5N2 >TNT@C5N2 >1,3-DNB@C5N2. The studied systems were further analysed by qualitative and quantitative analyses to determine the interactions between the nitroaromatic analytes and the C5N2 sheet. Electronic properties of all analytes@C5N2 complexes have been examined by NBO, EDD, FMO and DOS analysis. QTAIM analysis depicts the stronger non-covalent interactions for the PA@C5N2, which shows consistency with interaction energy and NCI analysis. Furthermore, NBO and FMO analyses show that the C5N2 substrate exhibits high sensitivity and selectivity towards the picric acid compared to TNT and 1,3-DNB nitroaromatics. EDD and DOS analyses are in agreement with NBO and FMO analyses. Furthermore, the recovery time of the studied system has been computed to determine the efficiency of C5N2 material as an electrochemical sensor. Overall, the results show that carbon nitride can be a good sensor for the detection of nitroaromatics.

Robust and facile detection of formaldehyde through transition metals doped olympicene sensors: a step forward DFT investigation

Formaldehyde, a volatile organic compound (VOC) released by building and decoration materials, has many applications in the chemical feedstock industry. Excessive release of formaldehyde can cause serious health issues, such as chest tightness, cough, cancer, and tissue damage. Therefore, detection of formaldehyde is required. Herein transition metal (Fe, Ni, and Pd) doped olympicene is evaluated as a gas sensor for the detection of formaldehyde. The performance of the designed electrochemical sensor is evaluated through interaction energy, natural bond orbital (NBO) non-covalent interaction (NCI), electron density differences (EDD), electrostatic potential (ESP), quantum theory of atom in molecule (QTAIM), frontier molecular orbital (FMO), and density of states (DOS) analysis. Interaction energies obtained at B3LYP-D3/def-2 TZVP level of theory shows that formaldehyde is physiosorbed over the surface of transition metal doped olympicene. The trend for interaction energy is OLY(Ni)/HCHO > OLY(Fe)/HCHO > OLY(Pd)/HCHO. The presence of non-covalent interactions is confirmed by the QTAIM and NCI analyses, while transfer of charges is confirmed by natural bond orbital analysis. The reduced density gradient (RDG) approach using noncovalent interaction (NCI) analysis demonstrates that electrostatic hydrogen bonding interactions prevail in the complexes. Recovery time is calculated to check the reusability of the sensor. This study may provide a deep insight for the designing of highly efficient electrochemical sensor against formaldehyde with transition metals doped on olympicene.

Metallofullerenes as Robust Single-Atom Catalysts for Adsorption and Dissociation of Hydrogen Molecules: A Density Functional Study

Hydrogen is currently considered as the best alternative for traditional fuels due to its sustainable and ecofriendly nature. Additionally, hydrogen dissociation is a critical step in almost all hydrogenation reactions, which is crucial in industrial chemical production. A cost-effective and efficient catalyst with favorable activity for this step is highly desirable. Herein, transition-metal-doped fullerene (TM@C60) complexes are designed and investigated as single-atom catalysts for the hydrogen splitting process. Interaction energy analysis (Eint) is also carried out to demonstrate the stability of designed TM@C60 metallofullerenes, which reveals that all the designed complexes have higher thermodynamic stability. Furthermore, among all the studied metallofullerenes, the best catalytic efficiency for hydrogen dissociation is seen for the Sc@C60 catalyst Ea = 0.13 eV followed by the V@C60 catalyst Ea = 0.19 eV. The hydrogen activation and dissociation processes over TM@C60 metallofullerenes is further elaborated by analyzing charge transfer via the natural bond orbital and electron density difference analyses. Additionally, quantum theory of atoms in molecule analysis is carried out to investigate the nature of interatomic interactions between hydrogen molecules and TMs@C60 metallofullerenes. Overall, results of the current study declare that the Sc@C60 catalyst can act as a low cost, highly efficient, and noble metal-free single-atom catalyst to efficiently catalyze hydrogen dissociation reaction.

Molecular docking, DFT studies, and anti-inflammatory evaluation of peshawaraquinone isolated from Fernandoa adenophylla

In recent years, there has been growing interest in exploring natural compounds with anti-inflammatory properties for potential therapeutic applications. This study focuses on investigating the anti-inflammatory potential of peshawaraquinone (PAQ), a compound isolated from Fernandoa adenophylla, which is known for its local use in pain relief. We aim to evaluate the efficacy of peshawaraquinone in both in vitro and in vivo models and gain insights into its mode of action. In the in vitro Human red blood cell (HRBC) assay, various concentrations of peshawaraquinone were tested for their ability to inhibit the hemolysis of red blood cells, a well-established indicator of anti-inflammatory activity. The results demonstrated a maximum percent inhibition of 79.69 at a concentration of 100 µM, indicating significant anti-inflammatory potential. Furthermore, the in vivo xylene-induced ear edema model was employed to assess the compound's efficacy in reducing inflammation. Xylene was topically applied to the ear to induce edema, and peshawaraquinone was administered to evaluate its inhibitory effects. The findings revealed a substantial 74.19% reduction in ear edema, accompanied by decreased ear thickness and histopathological improvements, such as inhibited cell infiltration and epidermal hyperplasia. To gain further insights into the compound's mechanism of action, density functional theory (DFT) calculations were performed to investigate its spectroscopic characteristics and geometric properties. Additionally, docking studies were conducted on key targets involved in inflammation, including COX-1 and COX-2. In conclusion, this study showcases the significant anti-inflammatory potential of peshawaraquinone, offering promising prospects for its use as a natural anti-inflammatory agent. The results from both in vitro and in vivo models, as well as the mechanistic insights gained from computational analyses, provide a solid basis for further exploration of peshawaraquinone's therapeutic applications.Communicated by Ramaswamy H. Sarma.

Enhanced nonlinear optical response of alkalides based on stacked Janus all-cis-1,2,3,4,5,6-hexafluorocyclohexane

Significant efforts are continuously exerted by the scientific community to explore new strategies to design materials with high nonlinear optical responses. An effective approach is to design alkalides based on Janus molecules. Herein, we present a new approach to remarkably boost the NLO response of alkalides by stacking the Janus molecules. Alkalides based on stacked Janus molecule, M-n-M' (where n = 2 & 3 while M and M' are Li/Na/K) are studied for structural, energetic, electrical, and nonlinear optical properties. The thermodynamic stability of the designed complexes is confirmed by the energetic stabilities, which range between -14.07 and -28.77 kcal/mol. The alkalide character of alkali metals-doped complexes is confirmed by the NBO charge transfer and HOMO(s) densities. The HOMO densities are located on the doped alkali metal atoms, indicating their alkalide character. The absorptions in UV-Vis and near IR region confirm the deep ultraviolet transparency of the designed complexes. The maximum first static and dynamic hyperpolarizabilities of 5.13 × 107 and 6.6 × 106 au (at 1339 nm) confirm their high NLO response, especially for K-2-M' complexes. The NLO response of alkalides based on stacked Janus molecules is 1-2 orders of magnitude higher than the alkalide based on Janus monomer. The high values of dc-Kerr and electric field-induced response e.g., max ∼107 and 108 au, respectively have been obtained. These findings suggest that our designed complexes envision a new insight into the rational design of stable high NLO performance materials.

Yttrium- and zirconium-decorated Mg12O12-X (X = Y, Zr) nanoclusters as sensors for diazomethane (CH2N2) gas

Diazomethane (CH2N2) presents a notable hazard as a respiratory irritant, resulting in various adverse effects upon exposure. Consequently, there has been increasing concern in the field of environmental research to develop a sensor material that exhibits heightened sensitivity and conductivity for the detection and adsorption of this gas. Therefore, this study aims to provide a comprehensive analysis of the geometric structure of three systems: CH2N2@MgO (C1), CH2N2@YMgO (CY1), and CH2N2@ZrMgO (CZ1), in addition to pristine MgO nanocages. The investigation involves a theoretical analysis employing the DFT/ωB97XD method at the GenECP/6-311++G(d,p)/SDD level of theory. Notably, the examination of bond lengths within the MgO cage yielded specific values, including Mg15-O4 (1.896 Å), Mg19-O4 (1.952 Å), and Mg23-O4 (1.952 Å), thereby offering valuable insights into the structural properties and interactions with CH2N2 gas. Intriguingly, after the interaction, bond length variations were observed, with CH2N2@MgO exhibiting shorter bonds and CH2N2@YMgO showcasing longer bonds. Meanwhile, CH2N2@ZrMgO displayed shorter bonds, except for a longer bond in Mg19-O4, suggesting increased stability due to shorter bond distances. The study further investigated the electronic properties, revealing changes in the energy gap that influenced electrical conductivity and sensitivity. The energy gap increased for Zr@MgO, CH2N2@MgO, CH2N2@YMgO, and CH2N2@ZrMgO, indicating weak interactions on the MgO surface. Conversely, Y@MgO showed a decrease in energy, suggesting a strong interaction. The pure MgO surface exhibited the ability to donate and accept electrons, resulting in an energy gap of 4.799 eV. Surfaces decorated with yttrium and zirconium exhibited decreased energies of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), as well as decreased energy gap, indicating increased conductivity and sensitivity. Notably, Zr@MgO had the highest energy gap before CH2N2 adsorption, but C1 exhibited a significantly higher energy gap after adsorption, implying increased conductivity and sensitivity. The study also examined the density of states, demonstrating significant variations in the electronic properties of MgO and its decorated surfaces due to CH2N2 adsorption. Moreover, various analysis techniques were employed, including natural bond orbital (NBO), quantum theory of atoms in molecules (QTAIM), and noncovalent interaction (NCI) analysis, which provided insights into bonding, charge density, and intermolecular interactions. The findings contribute to a deeper understanding of the sensing mechanisms of CH2N2 gas on nanocage surfaces, shedding light on adsorption energy, conductivity, and recovery time. These results hold significance for gas-sensing applications and provide a basis for further exploration and development in this field.

Transition Metal-Doped C20 Fullerene-Based Single-Atom Catalysts with High Catalytic Activity for Hydrogen Dissociation Reaction

Hydrogen dissociation is a key step in almost all hydrogenation reactions; therefore, an efficient and cost-effective catalyst with a favorable band structure for this step is highly desirable. In the current work, transition metal-based C₂₀ (M@C₂₀) complexes are designed and evaluated as single-atom catalysts (SACs) for hydrogen dissociation reaction (HDR). Interaction energy (E _int) analysis reveals that all the M@C₂₀ complexes are thermodynamically stable, whereas the highest stability is observed for the Ni@C₂₀ complex (E _int = -6.14 eV). Moreover, the best catalytic performance for H₂ dissociation reaction is computed for the Zn@C₂₀ catalyst (E _ads = 0.53 eV) followed by Ti@C₂₀ (E _ads = 0.65 eV) and Sc@C₂₀ (E _ads = 0.76 eV) among all considered catalysts. QTAIM analyses reveal covalent or shared shell interactions in H₂* + M@C₂₀ systems, which promote the process of H₂ dissociation over M@C₂₀ complexes. NBO and EDD analyses declare that transfer of charge from the metal atom to the antibonding orbital of H₂ causes dissociation of the H-H bond. Overall outcomes of this study reveal that the Zn@C₂₀ catalyst can act as a highly efficient, low-cost, abundant, and precious metal-free SAC to effectively catalyze HDR.

Hydrogen Dissociation Reaction on First-Row Transition Metal Doped Nanobelts

Zigzag molecular nanobelts have recently captured the interest of scientists because of their appealing aesthetic structures, intriguing chemical reactivities, and tantalizing features. In the current study, first-row transition metals supported on an H6-N3-belt[6]arene nanobelt are investigated for the electrocatalytic properties of these complexes for the hydrogen dissociation reaction (HDR). The interaction of the doped transition metal atom with the nanobelt is evaluated through interaction energy analysis, which reveals the significant thermodynamic stability of TM-doped nanobelt complexes. Electronic properties such as frontier molecular orbitals and natural bond orbitals analyses are also computed, to estimate the electronic perturbation upon doping. The highest reduction in the HOMO-LUMO energy gap compared to the bare nanobelt is seen in the case of the Zn@NB catalyst (4.76 eV). Furthermore, for the HDR reaction, the Sc@NB catalyst displays the best catalytic activity among the studied catalysts, with a hydrogen dissociation barrier of 0.13 eV, whereas the second-best catalytic activity is observed for the Zn@NB catalyst (0.36 eV). It is further found that multiple active sites, i.e., the presence of the metal atom and nitrogen atom moiety, help to facilitate the dissociation of the hydrogen molecule. These key findings of this study enhance the understanding of the relative stability, electronic features, and catalytic bindings of various TM@NB catalysts.

Efficient Detection of Nerve Agents through Carbon Nitride Quantum Dots: A DFT Approach

V-series nerve agents are very lethal to health and cause the inactivation of acetylcholinesterase which leads to neuromuscular paralysis and, finally, death. Therefore, rapid detection and elimination of V-series nerve agents are very important. Herein, we have carried out a theoretical investigation of carbon nitride quantum dots (C₂N) as an electrochemical sensor for the detection of V-series nerve agents, including VX, VS, VE, VG, and VM. Adsorption of V-series nerve agents on C₂N quantum dots is explored at M05-2X/6-31++G(d,p) level of theory. The level of theory chosen is quite adequate in systems describing non-bonding interactions. The adsorption behavior of nerve agents is characterized by interaction energy, non-covalent interaction (NCI), Bader's quantum theory of atoms in molecules (QTAIM), frontier molecular orbital (FMO), electron density difference (EDD), and charge transfer analysis. The computed adsorption energies of the studied complexes are in the range of -12.93 to -17.81 kcal/mol, which indicates the nerve agents are physiosorbed onto C₂N surface through non-covalent interactions. The non-covalent interactions between V-series and C₂N are confirmed through NCI and QTAIM analysis. EDD analysis is carried out to understand electron density shifting, which is further validated by natural bond orbital (NBO) analysis. FMO analysis is used to estimate the changes in energy gap of C₂N on complexation through HOMO-LUMO energies. These findings suggest that C₂N surface is highly selective toward VX, and it might be a promising candidate for the detection of V-series nerve agents.

Heteroatoms (Si, B, N, and P) doped 2D monolayer MoS2 for NH3 gas detection

2D transition metal dichalcogenide MoS2 monolayer quantum dots (MoS2-QD) and their doped boron (B@MoS2-QD), nitrogen (N@MoS2-QD), phosphorus (P@MoS2-QD), and silicon (Si@MoS2-QD) surfaces have been theoretically investigated using density functional theory (DFT) computation to understand their mechanistic sensing ability, such as conductivity, selectivity, and sensitivity toward NH3 gas. The results from electronic properties showed that P@MoS2-QD had the lowest energy gap, which indicated an increase in electrical conductivity and better adsorption behavior. By carrying out comparative adsorption studies using m062-X, ωB97XD, B3LYP, and PBE0 methods at the 6-311G++(d,p) level of theory, the most negative values were observed from ωB97XD for the P@MoS2-QD surface, signifying the preferred chemisorption surface for NH3 detection. The mechanistic studies provided in this study also indicate that the P@MoS2-QD dopant is a promising sensing material for monitoring ammonia gas in the real world. We hope this research work will provide informative knowledge for experimental researchers to realize the potential of MoS2 dopants, specifically the P@MoS2-QD surface, as a promising candidate for sensors to detect gas.