QTAIM Calculations Research Articles

Thorium(IV) and Uranium(IV) Thioether and Selenoether Complexes: Synthesis and An-ER2 (E = S, Se) Bonding Comparison.

Reactions of the rigid thioether- and selenoether-containing ligand salts [{Li(AE2Ph2)}2] (E = S or Se; AE2Ph2 = 4,5-bis(phenylchalcogenido)-2,7,9,9-tetramethylacridanide) with ThCl4(dme)2 or UCl4 (for E = Se) afforded the actinide chalcogenoether complexes [(AE2Ph2)2ThCl2] (E = S (1), Se (2)), and [(ASe2Ph2)2UCl2] (3). X-ray crystal structures of 1-3 revealed tetravalent actinide cations complexed to two κ3-coordinated AE2Ph2 ligands, with Th-ER2 and U-ER2 distances below the sum of the covalent radii. Complexes 1-3 provide extremely rare examples of thorium-thioether, thorium-selenoether, and uranium-selenoether bonds, and 1 and 2 contain the shortest known Th-SR2 and Th-SeR2 distances. DFT and QTAIM calculations confirm the presence of significant An(IV)-ER2 interactions in 1-3 and provide insight into the extent of covalency in the An-ER2 bonds.

New ATP-competitive inhibitors of E. coli GyrB obtained from the mapping of the hydrophobic floor at the binding site: synthesis and biological evaluation.

We mapped the hydrophobic floor, an interesting subsite at the active site of DNA gyrase B (GyrB) from E. coli. We synthesized three new compounds with pendant groups targeting the hydrophobic floor and evaluated their inhibitory activities on DNA gyrase. A new benzothiazole derivative with a benzyl substituent at position 3 of the benzothiazole ring exhibited strong inhibitory activity against E. coli DNA gyrase (IC50 = 19 ± 3 nM). An exhaustive conformational study using potential energy surfaces (PESs) allowed us to map the new subsite evaluating all critical points on the surface and conformational interconversion pathways. We analyzed the molecular interactions using QTAIM calculations. Our data provide insights into the mechanism of action of these new ligands at the molecular level. Theoretical and experimental data suggest that new ligand optimization strategies should focus on strengthening interactions at the hydrophobic floor while preserving the binding mode of the main scaffold.

New global minimum conformers for the Pt19\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{19}$$\\end{document} and Pt20\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{20}$$\\end{document} clusters: low symmetric species featuring different active sites

ContextThe study of platinum (Pt) clusters and nanoparticles is essential due to their extensive range of potential technological applications, particularly in catalysis. The electronic properties that yield optimal catalytic performance at the nanoscale are significantly influenced by the size and structure of Pt clusters. This research aimed to identify the lowest-energy conformers for Pt18\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{18}$$\\end{document}, Pt19\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{19}$$\\end{document}, and Pt20\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{20}$$\\end{document} species using Density Functional Theory (DFT). We discovered new low-symmetry conformers for Pt19\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{19}$$\\end{document} and Pt20\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{20}$$\\end{document}, which are 3.0 and 1.0 kcal/mol more stable, respectively, than previously reported structures. Our study highlights the importance of using density functional approximations that incorporate moderate levels of exact Hartree-Fock exchange, alongside basis sets of at least quadruple-zeta quality. The resulting structures are asymmetric with varying active sites, as evidenced by sigma hole analysis on the electrostatic potential surface. This suggests a potential correlation between electronic structure and catalytic properties, warranting further investigation.MethodsAn equivariant graph neural network interatomic potential (NequIP) within the Atomic Simulation Environment suite (ASE) was used to provide initial geometries of the aggregates under study. DFT calculations were performed with the ORCA 5 package, using functional approximations that included Generalized Gradient Approximation (PBE), meta-GGA (TPSS, M06-L), hybrid (PBE0, PBEh), meta-GGA hybrid (TPSSh), and range-separated hybrid (ω\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\omega $$\\end{document}B97x) functionals. Def2-TZVP and Def2-QZVP as well as members of the cc-pwCVXZ-PP family to check basis set convergence were used. QTAIM calculations were performed using the AIMAll suite. Structures were visualized with the AVOGADRO code.

Remediation of cationic dye from aqueous solution through adsorption utilizing natural Haloxylon salicornicum: An integrated experimental, physical statistics and molecular modeling investigation

Wastewater emanating from declining industrial processes often presents a vexing challenge due to its intricate composition replete with hazardous chemicals. The quest for environmentally sustainable methods to remediate such wastewater has led to the exploration of biomaterials as adsorbents and co-substrates within diverse treatment systems. In this study, we harnessed the abundant and cost-effective adsorbent, Haloxylon salicornicum (HS), as a potent agent for the removal of the pernicious triphenylmethane dye, crystal violet, from aqueous mediums. The adsorbent was characterised using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM), while Brunauer-Emmett-Teller (BET) analysis yielded a specific surface area (SBET) of 85.23 m2 g−1, highlighting its advantageous mesoporous structure for adsorption. Comprehensive investigations were conducted across various operational parameters, encompassing initial dye concentration, contact time, HS adsorbent dosage, initial pH, and temperature, with a keen focus on their influence on dye removal efficiency. The results unveiled several key trends, demonstrating that elevated initial dye concentration, prolonged contact time, and higher initial pH levels substantially enhanced the efficiency of dye removal, while ionic strength and temperature exhibited comparatively modest impacts. The kinetics of dye adsorption were rigorously examined, revealing a closer adherence to the pseudo-second-order model in comparison to the PFO model, thereby offering deeper insights into the adsorption dynamics. To further unravel the intricate mechanism underpinning the adsorption of CV on HS, we employed a single-layer model linked to SLMRG. In conjunction, DFT calculations, encompassing COSMO-RS, NCI, Molecular Dynamics (MD) simulations and QTAIM calculations, were applied to probe the interactions between adsorbed CV and the adsorbent-molecules, providing compelling evidence of robust binding interactions. These theoretical insights were subsequently aligned with empirical observations, affirming a significant relation between the theoretical and experimental data. This multifaceted study not only advances our understanding of CV removal using HS but also underscores the robustness of this adsorbent within the context of wastewater treatment. Furthermore, it demonstrates the synergy of empirical investigations and theoretical modeling in unraveling the intricacies of adsorption processes.

Metronidazole-Picric acid salt formation: Synthesis, characterization, Hirshfeld surface analysis, single crystal X-ray diffraction, computational studies, and molecular docking studies against Clostridioides difficile

The salt formation of metronidazole (MET) and picric acid (PA) is obtained via slow evaporation of their mixture in methanol which afforded a novel organic salt, C6H10N3O3+⋅C6H2N3O7- (METPA). The structure of METPA salt was analyzed using single crystal X-ray diffraction. METPA crystallizes in the triclinic space group P-1 with cell dimensions: a = 8.2446(1), b = 9.1843(1), c = 11.5832(2) Å, α = 106.190(1)°, β = 99.483(1)°, γ = 106.635(1)°, Volume (Å3) = 778.02(2) and Z = 2. The formation of METPA salt was analyzed by comparing the IR spectrum of MET, PA and METPA salt. In order to visualize the intermolecular interactions in the crystal of METPA salt, Hirshfeld surface analysis was employed. QTAIM calculations were performed using the AIMALL program package to estimate the strength of hydrogen bonding interactions in terms of bond critical points (BCP) and ring critical points (RCP). Molecular docking of the MET and METPA was conducted against three toxins of Clostridioides difficile such as C. difficile toxin A (TcdA), C. difficile toxin B (TcdB), C. difficile transferase (CDT). The results showed that the docking score calculated based on the knowledge-based iterative scoring function ITScore-PP indicates that METPA with higher negative value of docking score in case of all three toxins when compared to MET. This shows that the binding model of METPA salt is more favorable than MET.

Nature of Metal‐Metal Bond in Group‐V Dinuclear Metallaborane Compounds: Open‐Shell – Open‐Shell Vs Closed‐Shell – Closed‐Shell Interaction

The investigation of metal‐metal bonding is interesting due to the captivating structural features, unique chemical reactivity and physical properties of this class of complexes. The bonding situation in the metallaboranes [(Cp*)2M2(B2H6)2] of group‐V elements (M) in the +3 oxidation state [M = V (1), Ta (2)] was investigated by the DFT, NBO, QTAIM calculations and further with Energy Decomposition Analyses coupled with Natural Orbital for Chemical Valence (EDA‐NOCV). Even though the metallaboranes are isostructural, the nature of metal‐metal bonding interaction was found to be different, showing open‐shell ‐ open‐shell interaction for vanadium while closed‐shell – closed‐shell interaction between two tantalum atoms. The EDA‐NOCV analyses suggest that TaIII‐TaIII bonding interactions are stronger than those of divanadaborane analogue, having an intrinsic interaction energy of ‐247.6 kcal/mol (2), and the V‐V bond has an interaction energy of ‐192.5 kcal/mol (1). The analyses indicate that the strength of the metal‐metal bond becomes stronger as the metal becomes heavier. This is due to the higher contribution from electrostatic stabilization energy. The pairwise orbital analysis of the metal‐metal bond denotes significant dative‐interaction between two tantalum metals, contributing 52.6% (2) to total orbital interaction energy. The electron‐sharing interaction energy has been computed to be 44.3% for 1.

Unveiling the molecular insights of 2-(carboxymethyl) benzoic acid: A density functional theory approach towards structural and biological attributes

Nowadays density functional theory (DFT) is one of the best methods to explore the vibrational modes and structure of the biological system. Quantum mechanical calculations are performed using gas phase and different solvents (DMSO, methanol and water). The derived global reactive parameters, structural and topological study provides the clear insight of the 2-(Carboxymethyl) benzoic acid. Depth studies of DFT proves the existence of hydrogen bonds between donor and acceptor in the compound, which is supportive for the biological applications. In this paper, different experimental and computational simulated FT-IR, FT-Raman, UV–Vis spectral studies are used to explicate vibration assignments of the 2-(Carboxymethyl) benzoic acid. Experimentally observed vibrational frequency is compared with theoretically simulated spectrum. B3LYP method with 6–311++G (d, p) basis set is used in DFT to optimize the 2-(Carboxymethyl)benzoic acid structure. The most stable lower energy conformer is identified using potential energy surface (PES) analysis using Gaussian 16 W software. ESP, HOMO-LUMO, NBO, and QTAIM calculations have evinced an adequate electronic characterization of 2-(Carboxymethyl) benzoic acid. Further, van der Waals and steric interactions among 2-(Carboxymethyl) benzoic acid have been discussed with the help of RDG study. Hirshfeld surface studies establish the existing various interaction among molecules and total packing arrangement of the crystal structure. Due to the high biological activity score, 2-(Carboxymethyl) benzoic acid is a good therapeutic candidate. Lipophilicity analysis of 2-(Carboxymethyl)benzoic acid clearly explicates the bioactivity properties and its effective drug applications. Further, molecular docking investigates that the compound can be used as anticancer medication. The detailed DFT study of the 2-(Carboxymethyl) benzoic acid justified its biological applications of the present communication. The calculated NLO parameters of 2-(Carboxymethyl)benzoic acid evidenced for good efficacy in diverse filed application has been discussed.

Synthesis, Crystal Structure, Hirshfeld Surface Analysis, and Computational Approach of a New Pyrazolo[3,4-g]isoquinoline Derivative as Potent against Leucine-Rich Repeat Kinase 2 (LRRK2).

Ethyl-2-((8-cyano-3,5,9a-trimethyl-1-(4-oxo-4,5-dihydrothiazol-2-yl)-4-phenyl-3a,4,9,9a-tetrahydro-1H-pyrazolo[3,4-g]isoquinolin-7-yl)thio)acetate (5) was synthesized, and its structure was characterized by IR, MS, and NMR (1H and 13C) and verified by a single-crystal X-ray structure determination. Compound 5 adopts a "pincer" conformation. In the crystal, the hydrogen bonds of -H···O, C-H···O, and O-H···S form thick layers of molecules that are parallel to (101). The layers are linked by C-H···π(ring) interactions. The Hirshfeld surface analysis shows that intermolecular hydrogen bonding plays a more important role than both intramolecular hydrogen bonding and π···π stacking in the crystal. The intramolecular noncovalent interactions in 5 were studied by QTAIM, NCI, and DFT-NBO calculations. Based on structural activity relationship studies, leucine-rich repeat kinase 2 (LRRK2) was found to bind 5 and was further subjected to molecular docking studies, molecular dynamics, and ADMET analysis to probe potential drug candidacy.

Extraction of uranyl from spent nuclear fuel wastewater via complexation—a local vibrational mode study

ContextThe efficient extraction of uranyl from spent nuclear fuel wastewater for subsequent reprocessing and reuse is an essential effort toward minimization of long-lived radioactive waste. N-substituted amides and Schiff base ligands are propitious candidates, where extraction occurs via complexation with the uranyl moiety. In this study, we extensively probed chemical bonding in various uranyl complexes, utilizing the local vibrational modes theory alongside QTAIM and NBO analyses. We focused on (i) the assessment of the equatorial O-U and N-U bonding, including the question of chelation, and (ii) how the strength of the axial U=\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$=$$\\end{document}O bonds of the uranyl moiety changes upon complexation. Our results reveal that the strength of the equatorial uranium-ligand interactions correlates with their covalent character and with charge donation from O and N lone pairs into the vacant uranium orbitals. We also found an inverse relationship between the covalent character of the equatorial ligand bonds and the strength of the axial uranium-oxygen bond. In summary, our study provides valuable data for a strategic modulation of N-substituted amide and Schiff base ligands towards the maximization of uranyl extraction.MethodQuantum chemistry calculations were performed under the PBE0 level of theory, paired with the relativistic NESCau Hamiltonian, currently implemented in Cologne2020 (interfaced with Gaussian16). Wave functions were expanded in the cc-pwCVTZ-X2C basis set for uranium and Dunning’s cc-pVTZ for the remaining atoms. For the bonding properties, we utilized the package LModeA in the local modes analyses, AIMALL in the QTAIM calculations, and NBO 7.0 for the NBO analyses.Graphical abstract

Synthesis, structural characterization, and quantum chemical study of the 7-acetyl-5-nitrobenzofurans as anticancer agents with antioxidant properties

Synthesis of 7-acetyl-2-aryl-5-nitrobenzofurans 2a–j involved sequential Sonogashira cross-coupling of 2-hydroxy-3-iodo-5-nitroacetophenone with terminal acetylenes and in situ Cacchi-type cycloisomerization of 5-alkynylated intermediates. Hirshfeld's fingerprint diagrams and surface analysis showed varied intermolecular interactions. Additionally, intramolecular interactions were examined using DFT and QTAIM calculations. Benzofuran derivatives were tested for antiproliferative efficacy in vitro against MDA-MB-231 and Caski cell lines. The 1-(5-nitro-2-(p-tolyl)benzofuran-7-yl)ethan-1-one 2h showed promising antiproliferative activity against Caski and MDA-MB-231 cell lines, with IC50 values of 26.96 ± 4.97 µM and 5.13 ± 0.86 µM, respectively, compared to Camptothecin (IC50 = 8.96 ± 0.23 and 24.69 ± 0.26 µM). Derivatives with 2-(4-fluorophenyl)-2c, 2-(4-methoxyphenyl)- 2g, and 2-(3,5-bis(trifluoromethyl)phenyl)-2j groups showed significant antioxidant activity, with Fe-reducing power values of 520.14 ± 1.34 µM, 433.50 ± 1.30 µM, and 466.08 ± 1.91 µM, respectively, compared to ascorbic acid (IC50 = 538.05 µM). The most active molecules that docked with protease (2c, 2g, and 2j) and FKBP12-mTOR (2d, 2h and 2j) active site residues showed significant interactions which were confirmed by Molecular dynamic simulation. ADME investigation indicated drug-like characteristics, safe in silico toxicity, and no carcinogenic or mutagenicity.

3-(2-pyridyl)-5-(4-chlorophenyl)-1,2,4-triazine as a ligand: Synthesis of three lead(II) complexes, a spectroscopic and structural study using experimental and theoretical methods

Three new Pb(II) complexes of the ligand 3-(2-pyridyl)-5-(4-chlorophenyl)-1,2,4-triazine (pcpt) and different anionic co-ligands (1: bromide, 2: iodide and 3: isothiocyanate) were synthesized and characterized by elemental (CHN) analysis, FT-IR and 1H NMR spectroscopy and single crystal X-ray diffraction (SC-XRD). Considering only strong primary coordination bonds, the Pb(II) centres in complexes 1 and 2 are holodirectionally and in 3 hemidirectionally coordinated by the organic pcpt ligands due to stereochemical inactivity (1, 2) and activity (3) of the lone electron pair. The primary coordination sphere in 3 is sterically suitable for establishing interactions at longer distances, where the Pb centre acts as Lewis acid. Thus, all the Pb centers participate in Pb⋅⋅⋅Cl tetrel interactions, which together with secondary interactions of the ligands extend the structures into 1D supramolecular assemblies. A Hirshfeld surface inspection, along with the natural bond analysis (NBO), quantum theory of atoms in molecules (ATAIM), molecular electrostatistic potential (MEP) surface, and theoretical vibrational analysis at B3LYP/Def2-TZVP level of theory were conducted for the sake of further investigation of the non-covalent interactions in complexes 1–3. An enrichment ratio is also calculated for the chemical species to determine the tendency of their interactions in the crystal packing. The theoretical values obtained from the DFT at B3LYP/Def2-TZVP level of theory ensure that the expected consequences match the experimental findings. The QTAIM calculations allow the estimation of the strength of the primary and secondary/tetrel interactions and to propose the theoretical criteria based on the |VBCP|/GBCP, HBCP/ρBCP, and DI parameters for distinguishing the interactions. The MEP calculations confirmed the presence of a σ-hole in the proximity of the PbII centers.

Characteristics of Intermolecular Interactions between Encapsulated Molecules and the Lantern-Like Carcerand Superphanes

The main topic of the article is to provide the characteristics of individual intermolecular interactions present between three lantern-like superphanes and the H2O, NH3, HF, HCN, and MeOH molecules trapped inside them. Despite the large cavity, the freedom of the trapped molecules is significantly limited by the presence of numerous interaction sites on the side chains of the superphane molecule. It is shown that the molecule trapped inside the superphane is stabilized mainly by only one or, less often, two strong hydrogen bonds involving the imino nitrogen atom, but QTAIM calculations also suggest the presence of many other intermolecular interactions, mainly hydrogen bonds involving imino or central hydrogen atoms from the side chains of the superphane molecule. Moreover, it is also shown that the structural simplification of the side chains does not significantly affect both the size of the superphane molecule and the obtained encapsulation energies, which is important in modeling this type of carceplexes. Noticeably, the parent superphane considered here was previously synthesized by the group of Qing He, so the results obtained will help in understanding this type and similar systems.

Supramolecular motifs formed by CH3/Cl-substituted arene groups: evidence for structural differences in thiophosphoramides and similarities in their complexes.

Differences/similarities of supramolecular motifs are discussed in two new thiophosphoramide structures and their Ni molecular complexes: (C2H5O)2P(S)(NHC(S)NHCH2C6H4X) and [{(C2H5O)2P(S)(NC(S)NHCH2C6H4X)}2Ni] (X = Cl/CH3I/II and III/IV). The structures have equal numbers of donor/acceptor sites contributing to classical hydrogen bonds (PS/CS and 2 × NH in ligands and 2 × PS and 2 × NH in the complexes). However, these donor and acceptor sites contribute to inter/intramolecular hydrogen bonding in ligands and intramolecular hydrogen bonding in complexes. In the supramolecular assemblies of the ligands, the classic hydrogen bonds (N-H⋯S[double bond, length as m-dash]C) are restricted in dimer synthons, and the weaker interactions (formed by Cl/CH3 substituents) compete against each other. In the complexes, despite the lack of classic intermolecular hydrogen bond, numerous weak interactions, e.g., C-H⋯Y (Y = S, O, Ni, N, and π), contribute to the molecular assemblies, which do not include the participation of Cl/CH3. Thus, different packing features of ligands, but similar in complexes are observed. Each ligand and the associated complex show nearly equal supramolecular motifs in the slice of the substituted benzyl groups, related to the formation of C-H⋯Cl/π⋯π for the 4-Cl-C6H4CH2 groups in I/III and C-H⋯π for the 4-CH3-C6H4CH2 groups in II/IV. The repeatabilities of the motifs made by 4-Cl-C6H4CH2/4-CH3-C6H4CH2 were checked by surveying 142/844 structures with 178/1482 segments in the CSD, which show that 17% and 12% of the structures exhibited similarities with the title structures. The methods X-ray crystallography, 2D fingerprint plots, electrostatic potential surfaces, QTAIM, and energy framework calculations were applied to present the discussion.

Photoswitchable hydrazones with pyridine-based rotors and halogen substituents.

The Z,E-photoisomerization of pyridine-based hydrazone switches is typically suppressed due to the presence of pyridine-based rotors. The crystal structures of studied compounds were investigated using theoretical methods combining DFT and QT-AIM calculations to unveil the nature and properties of the intramolecular hydrogen bonding. In this study, we introduced a new series of pyridine-based hydrazones anchored with o-halogen substituents (2-X) and investigated their photoswitching abilities using 1H NMR and UV-Vis spectroscopy. The efficiency of the photoisomerization from initial 2-X-Z to the 2-X-E isomer varied, with the highest yield observed for 2-Cl-E (55%). Our findings, supported by DFT calculations, revealed the formation of a new diastereomer, 2-X-E*, upon back-photoisomerization. We demonstrated that hydrazones from the 2-X series can be reversibly photoswitched using irradiation from the UV-Vis range, and additionally, we explored the effect of the halogen atom on their switching capabilities and also on their thermodynamics and kinetics of photoswitching, determining their molecular solar thermal energy storage potential.

Small molecule activation by sila/germa boryne species.

The inability of p-block elements to participate in π-backbonding restricts them from activating small molecules like CO, H2 , and so forth. However, the development of the main group metallomimetics became a new pathway, where the main-group elements like boron can bind and activate small molecules like CO and H2 . The concept of the frustrated Lewis pair, Boron-Boron multiple bonds, and borylene are previously illustrated. Some of these reported classes of boron species can mimic the jobs of the metal complexes. Hence, we have theoretically studied the binding of CO/N2 molecules at B-center of elusive species like sila/germa boryne stabilized by donor base ligands (cAAC)BE(Me)(L), where E  Si, L  cAACMe , NHCMe , PMe3 , E  Ge, L  cAACMe and (NHCMe )BE(Me)(cAACMe )). The substitutional analogues of (cAACR )BSiR1 (cAAC) and E  P, L  cAACMe ) have been studied by density functional theory (DFT), natural bond orbital, QTAIM calculations and energy decomposition analysis (EDA) coupled with natural orbital for chemical valence (NOCV) analyses. The computed bond dissociation energy and inner stability analyses by the EDA-NOCV method showed that the CO molecule can bind at the B-center of the above-mentioned species due to stronger σ-donor ability while binding of N2 has been theoretically predicted to be weak. The energy barrier for the CO binding is estimated to be 13-14 kcal/mol by transition state calculation. The change of partial triple bond character to single bond nature of the BSi bond and the bending of CBSi bond angle of sila-boryne species are the reason for the activation energy. Our study reveals the ability of such species to bind and activate the CO molecule to mimic the transition metal-containing complexes. We have additionally shown that binding of Fe(CO)4 and Ni(CO)3 is feasible at Si-center after binding of CO at the B-center.

Mn(III)–Salen Complexes with Metallophilic Interactions

We synthesized a series of five novel Mn–salen-based compounds (1a–1c, 2a, 2b) through the reaction between precursor chloride complexes and potassium silver/gold dicyanide. The prepared compounds were structurally and magnetically characterized. Our findings revealed that all the Mn(III) central atoms exhibited an axially elongated coordination polyhedron, leading to the observation of axial magnetic anisotropy as indicated by the negative axial magnetic parameter D, which was determined through fitting the experimental magnetic data and supported by theoretical CASSCF/NEVPT2 calculations. Furthermore, we observed magnetic-exchange interactions only in compounds with a special supramolecular topology involving O–H···O hydrogen-bonded dimers. In these cases, the weak magnetic exchange (J/cm−1 = −0.58(2) in 1b and −0.73(7) in 2b) was mediated by the O–H···O hydrogen bonds. These findings were further supported by BS–DFT calculations, which predicted weak antiferromagnetic exchanges in these complexes and ruled out exchange interactions mediated by diamagnetic cyanido metallo–complex bridges. Additionally, we investigated the observed Ag···π (1b) and Au···Au (2b) interactions using QT–AIM calculations, confirming their non-covalent nature. We compared these results with previously reported Mn–salen-based compounds with metallophilic interactions arising from the presence of the [Ag/Au(CN)2]− bridging units.

Bonding Analysis of the Ge‐Ge Bonds in the Octagermacubane Ge8(Sit‐butyl2methyl)6

AbstractQuantum chemical calculations have been carried out at the BP86/def2‐SVP level on Ge8(Sit‐butyl2methyl)6(1) and the bonding situation has been analyzed with a variety of methods. The calculated equilibrium geometry of1is in good agreement with the reported x‐ray structure analysis. The D3 correction for dispersion interactions as a sum of pairwise attractions leads to an overestimate of the effect of dispersion forces. Calculations at BP86‐D3(BJ)/def2‐SVP give shorter bonds for Ge(I)−Ge(I) than for Ge(0)−Ge(I), which is in contrast to the experimental values and the BP86/def2‐SVP results. The NBO analysis suggests that the best Lewis structure of1has lone‐pair orbitals at the Ge(0) atoms with occupation numbers of 1.70 e. A lone‐pair character at Ge(0) albeit with less weight is also suggested by the shape of the HOMO, which is an antibonding orbital between the Ge(0) atoms with small contributions from the Ge(I) atoms. The LUMO of1is the corresponding bonding combination of the Ge(0) AOs, which can be explained with the reluctance of the heavier main‐group atoms to s/p hybridization of the valence orbitals. The calculated bond order values suggest significant direct Ge(0)−Ge(0) interactions. This is supported by the shape of the HOMO and by the results of EDA‐NOCV calculations. The deformation densities and the orbitals associated with the pairwise orbital interaction show that there is a direct charge flow between the Ge(0) atoms of the two fragments, but it is not completely separated from the Ge(0)−Ge(I) and Ge(I)−Ge(I) bond formation. The QTAIM calculations suggest that1has a cubic structure with a cage critical point but not a bond critical point for the Ge(0)−Ge(0) interactions. The dispersion interactions of the large substituents in1have a significant influence on the stability of the compound.

Structural, electronic, nonlinear optical properties and spectroscopic study of noble metals doped C60 fullerene using M06-2X

Structural, electronic, and nonlinear optical (NLO) properties of noble metals doped fullerenes (C60) were investigated using DFT calculations. The thermodynamic stability results reveal the stability of pristine and dopedC60 structures. The doping of C60nanocage with Ag, Au, and Pt atoms results in an increase in the reactivity with a charge transfer from carbon to noble metal atoms. The molecular reactivity descriptors show that PtC59is the softest (S = 0.74 eV) compound with a high electrophilicity (ω = 18.36 eV) and lower gap energy (Eg = 2.69 eV). The QTAIM calculations indicate that the dopant atoms are bounded to the adjacent carbon atoms through partially covalent bonds. The TD-DFT analysis proves that the maximum absorption wavelength is achieved with PtC59. In addition, doping enhances the NLO properties where a maximum first hyperpolarizability value (1.1 × 104 au) was observed for PtC59 and the doped fullerene surface becomes more optically active.

Coordination and Stabilization of a Lithium Ion with a Silylene.

Herein, we report the stabilization of lithium-ion as the source of lithium to use as a trans-metalation reagent [{PhC(Nt Bu)2 Si(t Bu)Li}2 I(t BuN)2 CPh] (1). The reaction of 3 equivalents of the LSit Bu (L=PhC(Nt Bu)2 ) and lithium iodide at low temperature leads to a silylene stabilized lithium-ion with an additional coordination of amidinate ligand. Compound 1 shows two four membered and one six membered ring as confirmed by QTAIM calculations. Whereas the reaction of the LSiCl with 1.5 equivalents of carbodiimide (CyN)2 C at room temperature affords compound [PhC(Nt Bu)2 Si(Cl)(NCy)2 NCy] (2) with the CN2 SiN2 C skeleton containing silicon as a central atom. Both the compounds were fully characterized by NMR, mass spectrometry, X-ray crystallographic analysis, and quantum mechanical calculations.

A novel series of thiosemicarbazone hybrid scaffolds: Design, synthesis, DFT studies, metabolic enzyme inhibition properties, and molecular docking calculations

The fourteen new thiosemicarbazone derivatives of Schiff base were synthesized from the condensation reactions of two different aldehydes (3‑hydroxy-4-methoxhybenzaldehyde and 3-ethoxhy-4-hydroxybenzaldehyde) with various substituted-thiosemicarbazides. Structures of the compounds (1-14) were characterized by using FT-IR, 1H NMR, and 13C NMR spectroscopic techniques, and elemental analysis. Furthermore, the enzyme inhibitory effect of the obtained hybrid scaffolds was studied. They exhibited highly potent inhibition effect on acetylcholinesterase (AChE) and carbonic anhydrases (hCAs) (KI values are in the range of 111.00 ± 12.12 to 381.60 ± 38.10 nM, 120.60 ± 20.45 to 338.90 ± 42.18 nM, and 100.60 ± 11.31 to 285.30 ± 45.27 nM for AChE, hCA I, and hCA II, respectively). DFT analyzes were performed to demonstrate the usability of some electronic parameters and nucleophilic-electrophilic attack abilities of the compounds in predicting enzyme inhibition properties. A correlation was seen between the HOMO energy eigenvalues of the compounds and the inhibition reactivity, and revealing that QTAIM calculations could also be used to predict the probability of electrophilic and nucleophilic attacks. Findings supporting that hCA I and AChE enzyme inhibition reactions primarily proceed through electrophilic attack, while hCA II reactions tend to occur via nucleophilic attack have been obtained. Also, molecular docking studies were conducted to confirm the outcomes of studies on binding affinities and the most powerful derivatives. The obtained results showed that the novel thiosemicarbazone derivatives may lead to the development of novel types of pharmacological agents in the treatment of patients with Alzheimer's disease, idiopathic intracranial hypertension, glaucoma, and related conditions.