Trigonal Bipyramidal Structure Research Articles

Photoelectron Spectroscopy and Theoretical Studies on the Structures and Properties of Ge4C- and Ge4CH- Clusters.

We investigate the structures and properties of Ge4C-/0 and Ge4CH-/0 clusters using anion photoelectron spectroscopy and theoretical calculations. Our calculations show that the first two low-lying isomers coexist in the experiments of Ge4C- and Ge4CH-. The first two low-lying isomers of Ge4C- have trigonal bipyramidal structures with the C atom on the equatorial plane and the top vertex, respectively. It is found that the first two low-lying isomers of Ge4CH- can be obtained by adding an H atom to the top and equatorial C atoms of Ge4C-, respectively. The AdNDP analyses reveal that the C atom in Ge4C forms one 4c-2e σ bond, two 4c-2e π bonds, and one 5c-2e σ bond with Ge atoms. The C atom in Ge4C interacts with an H- forming a C-H σ bond in Ge4CH-. AIMD simulation results indicate high dynamic stabilities of Ge4C and Ge4CH- at 300 and 500 K. Our results show that the structures and chemical bonding of Ge4B- and Ge4N+ are similar to those of Ge4C, while those of Ge4BH2- and Ge4NH resemble those of Ge4CH-.

Synthesis, structures, and cytotoxicity insights of organotin(IV) complexes with thiazole-appended pincer ligand

Diorganotin complexes of the compositions [Me2Sn(L)] (1), [n-Bu2Sn(L)] (2), [Ph2Sn(L)]⋅C6H6 (3), [Bz2Sn(L)]⋅C6H6 (4) and [n-Oct2Sn(L)] (5) were synthesized by reacting R2SnO (R = Me, n-Bu, Ph, Bz or n-Oct) with the N2,N6-di(thiazol-2-yl)pyridine-2,6-dicarboxamide (H2L, where H2 denotes the two acidic protons) in refluxing toluene. Additionally, the mono-n-butyltin complex [n-BuSn(HL)Cl2]·H2O (6) was synthesized from n-BuSnCl3 and H2L in acetonitrile. Compounds were characterized by FT-IR, 1H, 13C and 119Sn NMR spectroscopy, while their solid-state structures were examined using single-crystal X-ray diffraction studies. In diorganotin compounds 1–5, the dianionic tridentate ligands (Npy, N−, N−) act as κ-N3 chelators. In 6, the L moiety (O, Npy, N−) acts as a κ-ON2 tridentate chelator, with involvement of one of the carboxamide oxygen atoms. The coordination polyhedron around the Sn(IV) ion is completed either by two axial Sn-R ligands in compounds 1–5 or by n-Bu and Cl ligands in compound 6, giving rise to distorted trigonal bipyramid or octahedral structures, respectively. The tin NMR results show that the penta-coordinated structures of compounds 1–5 and the hexacoordinated structure of compound 6, observed in the solid-state, are retained in solution. The in vitro antitumor activities of 1–5 were tested on T-47D breast cancer cells. Of these, diphenyltin compound 3 showed the highest anti-proliferative effect, with an IC50 of 10 ± 1.60 μM. Compound 3 exhibited selective toxicity, potentially inducing apoptosis via reactive oxygen species generation and nuclear changes, indicating promise as a breast cancer treatment. This study is the first to explore thiazole-appended organotin compounds for cytotoxicity.

Protective effect of the perchlorophenyl group in organophosphorus chemistry

The homoleptic phosphine with the bulky perchlorophenyl group, (C6Cl5)3P (1), exhibits trigonal pyramidal structure (TPY-3), yet considerably flattened: Σ(C–P–C') = 321.0(1)°. Key steric and electronic properties of this simple organophosphorus species have been estimated by calculation. Attending to its characteristic features, 1 can be rated as a deactivated phosphine, where the less-basic P atom is sterically shielded by the bulky C6Cl5 groups. This marked inertness notwithstanding, it has been possible to obtain (under harsh conditions) derivatives with phosphorus in high oxidation state, namely the phosphine oxide (C6Cl5)3PO (2) and the difluorophosphorane (C6Cl5)3PF2 (3). These four- and five-substituted derivatives respectively exhibit trigonal pyramidal (TPY-4) and trigonal bipyramidal (TBPY-5) structures. The Σ(C–P–C') value steadily increases along the series 1–3, according to the referred structural variation. The P–C bond length is, in turn, invariably maintained at about 185 pm regardless of the different oxidation state, the increasing number of substituents around the P atom and the overall geometry. The hypervalent difluorophosphorane (C6Cl5)3PF2 (3) dissociates one of the axial fluorides in the gas phase giving rise to the fluorophosphonium cation [(C6Cl5)3PF]+, as detected by mass spectrometry. This cation is identified as a Lewis superacid.

Theoretical Study on the Mechanism of Ru(II)-Catalyzed Intermolecular [3 + 2] Annulation between o-Toluic Acid and 3,5-Bis(trifluoromethyl)benzaldehyde: Octahedral vs Trigonal Bipyramidal.

Density functional theory was utilized to investigate the mechanism of Ru(II)-catalyzed aromatic C-H activation and addition of aromatic aldehydes. The proposed catalytic cycle consists of C-H bond activation, aldehyde carbonyl insertion for C-C coupling, lactonization for the formation of the final product, product separation, and catalyst recovery. Our calculations suggest that Ru(OAc)2(PCy3) (referred to as CAT) is the most favorable active catalyst, facilitating the C-H bond activation to form a five-membered ring cycloruthenium intermediate (INT2). Subsequently, the aromatic aldehyde reactant 2a enters the Ru coordination sphere, accelerating the C-C coupling and lactonization for the formation of the final product. The involvement of acetate assists in the final product separation, while INT1 re-enters the Ru coordination sphere to initiate a new catalytic cycle. Utilizing the energetic span model, the apparent activation free energy barrier was computed to be 34.3 kcal mol-1 at 443 K. Furthermore, exploration of the reaction mechanism in the absence of phosphine ligands identified Ru(OAc)2(p-cymene) as the most favorable active catalyst. The derived apparent activation free energy barrier offers a comprehensive explanation for the experimentally observed yields. Additionally, we have examined the disparities between the octahedral and trigonal bipyramidal structures of the catalysts concerning their effects on the reaction mechanisms and apparent activation free energy barriers.

Sonochemical synthesis, characterization, and ADMET studiesof Fe (II) and Cu (II) nano-sized complexes of trimethoprim

Nanoparticles exhibit distinct physical and chemical characteristics and are becoming increasingly significant in the production of innovative nanodevices for many applications in physics, biology, biomedicine, and pharmaceuticals. The aim of this research work is to synthesize Fe (II) and Cu (II) nano-sized complexes of trimethoprim (TMP) using the sonication method, characterize them using physical and spectroscopic methods, and carry out ADMET studies on the synthesized complexes. The spectroscopic and physical studies showed a change in colour and an increase in melting point due to coordination. The novel compounds were slightly soluble in water. The XRD tests revealed that the new nanocomplexes were crystalline. The Fe (II) nanocomplexes had a size of 57.56 nm and the Cu (II) nanocomplexes had a size of 69.88 nm. These values were found using Debye-Scherrer’s equation. The FTIR results of the TMP, Fe (II), and Cu (II) nanometal complexes showed a shift of the amino group band from 3317 to 3295 and 3202 cm?1 and the azomethine band from 1633 to 1625 and 1592 cm?1 in the complexes. In the complexes, the proton NMR spectra revealed an upfield shift of the amine proton. The carbon-13 NMR spectra showed that CH2 was involved in coordination with the metal ions. The spectra studies indicated that TMP coordinated with the metal ions through the methylene and amino groups. A trigonal bipyramid structure was proposed for the complexes. The results of the Rule of 5 studies indicated that the test compounds had a good drug-likeness prediction, with only one violation. The ADMET prediction showed that all of the compounds demonstrated improved pharmacokinetic characteristics and adhered to the RO5 requirement. These findings highlight the therapeutic potential of Fe (II) and Cu (II) nano-sized TMP complexes as bioactive compounds that warrant further investigation for pharmaceutical applications.

Synthesis, spectral, antibacterial and NLO properties of organotin(IV) complexes of Thiosemicarbazones and Semicarbazones

In this study, the antimicrobial and nonlinear optical (NLO) response of thiosemicarbazone, semicarbazone, and their organotin(IV) compounds have been investigated. Organotin(IV) complexes of various types, namely [R2Sn(PhTscz)2], [R2Sn(Tscz)2], [R2Sn(Scz)2], [Bu3Sn(PTscz)], [Bu3Sn(PTscz)], and [Bu3Sn(Scz)] (where R = n-Butyl; methyl; PhTsczH = (±) 2-isopropyl-5-methyl-cyclohexylidene)-N-phenylhydrazine-carboxamide, TsczH = (±) 2-isopropyl-5-methylcyclo-hexylidene)hydrazinecarbothioamide, SczH = (±) 2-isopropyl-5-methylcyclohexyli-dene)hydrazine-carboxamide), were synthesized and characterized by CHN analysis, molar conductivity, UV-Vis, FTIR, and NMR (1H, 13C, 119Sn) spectroscopy, along with theoretical evidence obtained through density functional theory (DFT) simulations. The results showed that the Schiff base (HL) ligands acts as a bidentate NO/NS donor with azomethine nitrogen (N) and deprotonated ketonic oxygen/thionic sulphur (O, S) atoms. [R2Sn(L)2] complexes are assigned a distorted octahedral structure, while Bu3Sn(L) complexes have distorted trigonal bipyramidal structures. The B3LYP/LanL2DZ programme theoretically discussed the electronic structure and nonlinear optical (NLO) properties of the synthesized compounds. The synthesised compounds were evaluated for antibacterial activity using the zone inhibition method. Antibacterial activity of the ligands and its metal complexes against Gram(+) and Gram(-) bacteria demonstrated that the organotin complexes are more potentially resistant to microbial activities than the free ligands. According to the reactivity parameter factors, compound Bu2Sn(Scz)2 (3) is less reactive and more stable. Nonlinear optical (NLO) study revealed that compound (3) had greater linear polarizability (α) values, whereas compound Me2Sn(Scz)2 (9) had higher first hyperpolarizability (βtot) values of 244.29 a.u. Because of their high initial hyperpolarizability values, these molecules have excellent non-linear optical properties and can be exploited as innovative materials in the construction of optoelectronic devices.

Classical versus Collective Interactions in Asymmetric Trigonal Bipyramidal Alkaline Metal-Boron Halide Complexes.

Collective interactions are a novel type of chemical bond formed between metals and electron-rich substituents around an electron-poor central atom. So far only a limited number of candidates for having collective interactions are reported. In this work, we extend the newly introduced concept of collective bonding to a series of neutral boron complexes with the general formula M2BX3 (M=Li, Na, and K; X=F, Cl, and Br). Our state-of-the-art ab initio computations suggest that these complexes form trigonal bipyramidal structures with a D3h to C3v distortion along the C3 axis of symmetry. The BX3 unit in the complexes distorts from planar to pyramidal akin to a sp3 hybridized atom. Interestingly, the interaction of the metals with the pyramidal side of BX3, where the lone pair in a hypothetical [BX3]2- should be located, is weaker than the interactions of metals with the inverted side, i. e., the middle of three halogen atoms. The origin of this stronger interaction can be explained by the formation of collective interactions between metals and halogen atoms as we explored via energy decomposition within the context of the theory of interacting quantum atoms, IQA.

Modeling Complex Ligands for High Oxidation State Catalysis: Titanium Hydroamination with Unsymmetrical Ligands.

A method for modeling high oxidation state catalysts is used on precatalysts with unsymmetrical and symmetrical bidentate ligands to get a more detailed understanding of how changes to ancillary ligands affect the hydroamination of alkynes catalyzed by titanium. To model the electronic donor ability, the ligand donor parameter (LDP) was used, and to model the steric effects, percent buried volume (% Vbur) was employed. For the modeling study, 7 previously unpublished unsymmetrical Ti(XX')(NMe2)2 precatalysts were prepared, where XX' is a chelating ligand with pyrrolyl/indolyl linkages. The rates of these unsymmetrical and 10 previously reported symmetrical precatalysts were used with the model kobs = a + b(LDP)1 + c(LDP)2 + d(% Vbur)1 + e(% Vbur)2, where a-e were found through least-squares refinement. The model suggests that (1) the two attachment points of the bidentate ligand XX' are in different environments on the metal (e.g., axial and equatorial in a trigonal bipyramidal or square pyramidal structure), (2) the position of the unsymmetrical ligand on the metal is determined by the electronics of the ligand rather than the sterics, and (3) that one side of the chelating ligand's electronics strongly influences the rate, while the other side's sterics more strongly influences the rate. From these studies, we were able to generate catalysts fitting to this model with rate constants larger than the fastest symmetrical catalyst tested.

σ-Hole Site-Based Interactions within Hypervalent Pnicogen, Halogen, and Aerogen-Bearing Molecules with Lewis Bases: A Comparative Study.

σ-Hole site-based interactions in the trigonal bipyramidal geometrical structure of hypervalent pnicogen, halogen, and aerogen-bearing molecules with pyridine and NCH Lewis bases (LBs) were comparatively examined. In this respect, the ZF5···, XF3O2···, and AeF2O3···LB complexes (where Z = As, Sb; X = Br, I; Ae = Kr, Xe; and LB = pyridine and NCH) were investigated. The electrostatic potential (EP) analysis affirmations outlined the occurrence of σ-holes on the systems under consideration with disparate magnitudes that increased according to the following order: AeF2O3 < XF3O2 < ZF5. In line with EP outcomes, the proficiency of σ-hole site-based interactions increased as the atomic size of the central atom increased with a higher favorability for the pyridine-based complexes over NCH-based ones. The interaction energy showed the most favorable negative values of -35.97, -44.53, and -56.06 kcal/mol for the XeF2O3···, IF3O2···, and SbF5···pyridine complexes, respectively. The preferentiality pattern of the studied interactions could be explained as a consequence of (i) the dramatic rearrangement of ZF5 molecules from the trigonal bipyramid geometry to the square pyramidal one, (ii) the significant and tiny deformation energy in the case of the interaction of XF3O2 molecules with pyridine and NCH, respectively, and (iii) the absence of geometrical deformation within the AeF2O3···pyridine and ···NCH complexes other than the XeF2O3···pyridine one. Quantum theory of atoms in molecules and noncovalent interaction index findings reveal the partially covalent nature of most of the investigated interactions. Symmetry-adapted perturbation theory affirmations declared that the electrostatic component was the driving force beyond the occurrence of the considered interactions. The obtained findings will help in improving our understanding of the effect of geometrical deformation on intermolecular interactions.

A Simple Manganese(I) Catalyst for the Efficient and Selective Hydrophosphination of Olefins with PH3, Primary, and Secondary Phosphanes.

A tridentate ligand L with a P,NH,N donor motif was synthesized in few steps from commercially available precursors. Upon reaction with [MnBr(CO)5], an octahedral 18-electron complex [Mn(CO)3(L)]Br (1) is obtained in which L adopts a facial arrangement. After deprotonation of the NH group in the cationic complex unit, a neutral Mn(I) amido complex [Mn(CO)2(L-H)] (2) is formed under loss of CO. Rearrangement of L-H leads to a trigonal bipyramidal structure in which the P and N donor centers are in trans position. Further deprotonation of 2 results in a dep-blue anionic complex fragment [Mn(CO)2(L-2H)]- (3). DFT calculations and a QTAIM analysis show that the amido complex 2 contains a Mn-N bond with partial double bond character and 3 an aromatic MnN2C2 ring. The anion [Mn(CO)2(L-2H)]- reacts with Ph2PH to give a phosphido complex, which serves as phosphide transfer reagent to activated olefins. But the catalytic activity is low. However, the neutral amido complex 2 is an excellent catalyst and with loadings as low as 0.04 mol %, turn over frequencies of >40'000 h-1 can be achieved. Furthermore, secondary and primary alkyl phosphines as well as PH3 can be added in a catalytic hydrophosphination reaction to a wide range of activated olefins such as α,β-unsaturated aldehydes, ketones, esters, and nitriles. But also, vinyl pyridine and some styrene derivatives are converted into the corresponding phosphanes.

Mineral dissolution mechanism of alite polymorphs from ReaxFF molecular dynamics and 29Si NMR investigations

The hydration of tricalcium silicate (C3S, C = CaO, S = SiO2) played a critical role in the mechanical property improvement in cement-based cementitious materials. In this study, we investigated the hydration mechanism of M3- and T1-C3S polymorphs using molecular dynamics simulation with the ReaxFF force field. Six surfaces were selected by their low-index surface energy and surface areas of the Wulff structure to study their hydration process, including M3-C3S (100), (001) and (111) surfaces, as well as T1-C3S (001), (010) and (111) surfaces. Bonding formation kinetics and radial distribution functions were analyzed. Results show that water dissociation degrees on the studied surfaces were comparable, independent of the crystal polymorphs. The final bond formation percent of Ca-OwH and Os/Oi-H on all the surfaces exhibited little difference. However, we observed the formation of pentacoordinate silicon atoms with a [SiO5]6- trigonal bipyramid structure, occurring earlier in M3-C3S than in T1-C3S. Furthermore, the M3-C3S exhibited a higher abundance of pentacoordinate silicon atoms compared to the T1 crystal, suggesting greater reactivity of M3-C3S. This study provided valuable insights into enhancing the quality of cement clinker and activating other silicate minerals in supplementary cementitious materials.

Regioselective Reductive Elimination from Bismuth(V) Compounds for Aryl Transfer to Nucleophiles

AbstractWe demonstrate that regioselective aryl transfer to the nucleophile occurs rapidly under mild conditions via reductive elimination and show that regioselectivity is primarily governed by steric factors imparted by ortho substituents on the recipient ring. Computational modeling and x‐ray crystallography confirm that the recipient aryl ring is positioned in the equatorial coordination site and oriented orthogonally to the axial X−Bi−Ph bond (X=nucleophile) in a trigonal bipyramidal structure. The orientation of the ortho‐substituted aryl ring allows the appropriate orbital to overlap between its ipso carbon and nucleophile, which enhances the rate of aryl transfer to the nucleophile and dictates the regioselective reductive elimination from Bi(V) compounds. This level of stereoelectronic control results in significantly enhanced reaction rate and selectivity and creates an opportunity to rationally design ligand systems for selective aryl transfer reactions.

Aggregation-induced enhanced fluorescence emission of chiral Zn(II) complexes coordinated by Schiff-base type binaphthyl ligands.

A pair of novel chiral Zn(II) complexes coordinated by Schiff-base type ligands derived from BINOL (1,1'-bi-2-naphthol), R-/S-Zn, were synthesized. X-ray crystallography revealed the presence of two crystallographically independent complexes; one has a distorted trigonal-bipyramidal structure coordinated by two binaphthyl ligands and one disordered methanol molecule (molecule A), while the other has a distorted tetrahedral structure coordinated by two binaphthyl ligands (molecule B). Numerous CH⋯π and CH⋯O interactions were identified, contributing to the formation of a 3-dimensional rigid network structure. Both R-/S-Zn exhibited fluorescence in both CH2Cl2 solutions and powder samples, with the photoluminescence quantum yields (PLQYs) of powder samples being twice as large as those in solutions, indicating aggregation-induced enhanced emission (AIEE). The AIEE properties were attributed to the restraint of the molecular motion arising from the 3-dimensional intermolecular interactions. CD and CPL spectra were observed for R-/S-Zn in both solutions and powders. The dissymmetry factors, gabs and gCPL values, were within the order of 10-3 to 10-4 magnitudes, comparable to those reported for chiral Zn(II) complexes in previous studies.

Ortho-Vanillin-based fluorescent sensor with ESIPT characteristics for selective detection of Al(III) in aqueous solutions and its application for plant and live-cell imaging

A new acylhydrazone fluorescent sensor (VN62) with excited intramolecular proton transfer (ESIPT) characteristics has been designed and synthesized through condensation of o-vanillin with 6‑hydroxy-2-naphthoic hydrazide for selective detection of Al3+ in aqueous medium. The structure of the VN62 sensor was characterized by various techniques such as 1H and 13C NMR and mass spectrometry, and also confirmed by single crystal X-ray diffraction. The VN62 sensor showed a remarkable fluorescence enhancement response to Al3+ over a broad pH range in a nearly 100 % aqueous solution without interference by most of tested metal ions and anions. Through fluorescence titration and a Job's plot experiment, the binding stoichiometry of VN62 with Al3+ was found to be 1:1. The limit of detection of VN62 toward Al3+ was determined as 39.6 nM and the binding constant was 2.66 × 104 M−1. Comprehensive analyses by HR-MS, 1H NMR and density functional theory calculations illustrated that the VN62 sensor coordinated with Al3+, forming a stable trigonal bipyramid structure complex, which blocked the ESIPT and photoinduced electron transfer processes and simultaneously promoted an intramolecular charge transfer process, thereby leading to strong cyan fluorescence. Moreover, VN62-loaded test strips were successfully applied for rapid and visual detection of Al3+. Furthermore, the VN62 sensor was used to visualize Al3+in plants and live cells. The results indicated that the VN62 sensor has great potential for detecting Al3+in biological systems.

Anion Photoelectron Spectroscopy and Theoretical Studies of Ge3n+1O (n = 1-3) Clusters with the C3v Symmetric Ge3 Structural Unit.

We investigate Ge3n+1O-/0 (n = 1-3) clusters using anion photoelectron spectroscopy and theoretical calculations. The results show that the lowest energy structure of Ge4O- is a bent Cs symmetric trigonal bipyramidal structure, while Ge4O has a C3v symmetric trigonal bipyramidal structure. Ge7O- has two coexisting low-lying isomers, the first one can be viewed as a Ge2O unit interacting with a Ge5 trigonal bipyramid, the second one can be regarded as an O atom interacting with a Ge7 pentagonal bipyramid; whereas Ge7O has a C3v symmetric structure with a Ge atom and an O atom capping a Ge6 trigonal antiprism from the bottom and top, respectively. The structures of Ge10O- and Ge10O can be obtained by adding an O atom to different binding sites of a C3v symmetric Ge10. Chemical bonding analyses of Ge3n+1O (n = 1-3) reveal that the O atom interacts with its neighboring three Ge atoms forming one 4c-2e σ bond and two 4c-2e π bonds in the top Ge3O trigonal pyramid, while the terminal Ge atom forms one 4c-2e σ bond in the bottom Ge4 trigonal pyramid. The large HOMO-LUMO gaps of Ge3n+1O (n = 1-3) indicate that they have good stabilities. Ab initio molecular dynamics simulations suggest that both Ge7O and Ge10O are dynamically stable in general at 300 and 500 K. The current work suggests that the C3v symmetric Ge3 units and the insertion growth pattern may be viable for constructing 1D germanium oxide nanostructures with the chemical formula of Ge3n+1O.

Supported Metal Nanohydrides for Hydrogen Storage

Adsorption of hydrogen on graphdiyne (GDY) and boron-graphdiyne (BGDY) doped with palladium clusters has been investigated by performing density functional calculations. Pd6 fits well on the large holes of those porous layers, preserving its octahedral structure in GDY and changing it to a capped trigonal bipyramid structure in BGDY. Pd6GDY adsorbs up to five H2 molecules with sizable adsorption energies, two dissociated and three nondissociated. The dissociation barrier of H2 on the Pd6GDY cluster is 0.58 eV. Pd6BGDY can adsorb up to six molecules, three dissociated and three nondissociated, and the dissociation barrier of H2 on Pd6BGDY is 0.23 eV. In both cases, the dissociation barriers are substantially smaller than the corresponding dissociation barriers on undoped GDY and BGDY. The Pd clusters saturated with hydrogen can be viewed as nanohydrides. Spilling of the adsorbed hydrogen atoms toward the GDY and BGDY substrates is hindered by large activation barriers. We then propose using BGDY and GDY layers as support platforms for metal nanohydrides. The amount of stored hydrogen using Pd as the dopant is below the target of 6% of hydrogen in weight, but replacing Pd by a lighter metal with similar or higher affinity for hydrogen would substantially enhance the storage.

Solvation Structure and Dynamics of Aqueous Solutions of Au+ Ions: A Molecular Dynamics Simulation Study

Although gold (Au) as an element is precious and noble, its elemental as well as ionic form is of huge scientific importance in view of its applications in electrochemistry, nano-electronics and other related fields. We have studied structure and dynamics of aqueous solutions of gold ions (Au+) using molecular dynamics simulations. Using a modified LJ parameter set for the Au+ ions in water in our molecular dynamics simulations, we have established the hydration structure and dynamics of Au+ ions in terms of radial distributions, orientations and residence time of the nearest neighbours. Our results on peak position, height and coordination numbers are in much better agreement with those from the recent CPMD simulations. Relative orientation of the neighbours as obtained from the angular distributions suggests octahedral or trigonal bi-pyramidal structure of the solvation shell. Orientational distributions of dipoles and other molecular orientational vectors indicate that the hydrogen atoms of the water molecules are away from the central Au+ ion. The residence time calculated from the corresponding time correlation function is found to be reasonably high, indicating less exchange of water molecules between the first and second solvation shells of the Au+ ion. In essence, the present results are in much better agreement with the CPMD results as compared to other QM/MM and classical force-field-based simulations.

Ligational behavior of bidentate nitrogen–oxygen donor 8‐quinolinolazodye toward Ni2+ and Zn2+ ions: Preparation, spectral, thermal, experimental, theoretical, and docking studies

The 5‐(4‐aryl azo)‐8‐hydroxyquinolines (L1–L3) and their metal complexes with Ni2+ and Zn2+ have been produced. Various spectroscopic techniques have been employed to analyze the ligand and complexes. The structures of the prepared compounds have been confirmed by Fourier transform infrared (FT‐IR), proton nuclear magnetic resonance (1H NMR), molar conductance, magnetic measurements, thermal gravimetric and differential thermal analyses (TG and DTA), and electronic transition. The FT‐IR spectra showed that the ligands are coordinated to the metal ions in a bidentate manner with donor sites of the azomethine‐N and phenolic‐OH. The FT‐IR and UV–Visible spectra were compared with the calculated results and showed a good agreement. The mass spectra concluded that the ligands' molecular weights and the calculated estimated m/z values match well. The complexes contain coordinated and hydrated water as confirmed by the TG results. The complexes are tetrahedral, trigonal bipyramid, and octahedral geometrical structures and act as non‐electrolytes in dimethylformamide (DMF) solvent. Using density functional theory (DFT) at the B3LYP level of theory and the 6‐311G** basis set for the C, H, N, Cl, and O atoms and the LANL2DZ basis set for the Ni and Zn atoms. Natural bond orbital (NBO) analysis was used to compute and describe the natural charge population and precise electronic configuration. The small energy gap between HOMO and LUMO energies suggests that charge transfer occurs within Ni2+ and Zn2+ complexes. The first‐order hyperpolarizability (β) of the complexes and the anisotropy of polarizability (α) values show promising optical properties. The electronic transitions of the prepared complexes were computed by time‐dependent density functional theory (TD‐DFT/PCM) with the B3LYP method using a 6‐31G** basis set. The ethanol polarizable continuum model (PCM) was used to simulate the solvent effect. Utilizing a computer virtual screening technique through molecular docking, the anticipation of binding of 8‐quinolinolazodye derivatives and their complexes with human CORONA virus protein (PDB ID: 5epw) was done.

Catalytic activation of remote alkenes through silyl-rhodium(III) complexes.

The tandem isomerization-hydrosilylation reaction is a highly valuable process able to transform mixtures of internal olefins into linear silanes. Unsaturated and cationic hydrido-silyl-Rh(III) complexes have proven to be effective catalysts for this reaction. Herein, three silicon-based bidentate ligands, 8-(dimethylsilyl)quinoline (L1), 8-(dimethylsilyl)-2-methylquinoline (L2) and 4-(dimethylsilyl)-9-phenylacridine (L3), have been used to synthesize three neutral [RhCl(H)(L)PPh3] (1-L1, 1-L2 and 1-L3) and three cationic [Rh(H)(L)(PPh3)2][BArF4] (2-L1, 2-L2 and 2-L3) Rh(III) complexes. Among the neutral compounds, 1-L2 could be characterized in the solid state by X-ray diffraction showing a distorted trigonal bipyramidal structure. Neutral complexes (1-L1, 1-L2 and 1-L3) failed to catalyze the hydrosilylation of olefins. On the other hand, the cationic compound 2-L2 was also characterized by X-ray diffraction showing a square pyramidal structure. The unsaturated and cationic Rh(III) complexes 2-L1, 2-L2 and 2-L3 showed significant catalytic activity in the hydrosilylation of remote alkenes, with the most sterically hindered (2-L2) being the most active one.

Morphing Wing Based on Trigonal Bipyramidal Tensegrity Structure and Parallel Mechanism

The development of morphing wings is in the pursuit of lighter weight, higher stiffness and strength, and better flexible morphing ability. A structure that can be used as both the bearing structure and the morphing mechanism is the optimal choice for the morphing wing. A morphing wing composed of a tensegrity structure and a non-overconstrained parallel mechanism was designed. The self-balancing trigonal bipyramidal tensegrity structure was designed based on the shape-finding method and force-equilibrium equation of nodes. The 4SPS-RS parallel mechanism that can complete wing morphing was designed based on the configuration synthesis method. The degree of freedom and inverse solution of the parallel mechanism was obtained based on the screw theory, and the Jacobian matrix of the parallel mechanism was established. The stiffness model of the tensegrity structure and the 4SPS-RS parallel mechanism was established. The relationship between the deformation of the 4SPS-RS parallel mechanism and sweep angle, torsion angle, spanwise bending, and span was obtained. Through the modular assembly and distributed drive, the morphing wing could perform smooth and continuous morphing locally and globally. In the static state, it has the advantages of high stiffness and large bearing capacity. In the process of morphing, it can complete morphing motion with four degrees of freedom in changing sweep, twist, spanwise bending, and span of the wing.