Search

A full-dimensional analytical potential energy surface (PES) is developed for the Cl + CH3CN reaction following our previous work on the benchmark ab initio characterization of the stationary points. The spin–orbit-corrected PES is constructed using the Robosurfer program and a fifth-order permutationally invariant polynomial method for fitting the high-accuracy energy points determined by a ManyHF-based coupled-cluster/triple-zeta-quality composite method. Quasi-classical trajectory simulations are performed at six collision energies between 10 and 60 kcal mol−1. Multiple low-probability product channels are found, including isomerization to isonitrile (CH3NC), but out of the eight possible channels, only the H-abstraction has significant reaction probability; thus, detailed dynamics studies are carried out only for this reaction. The cross sections and opacity functions show that the probability of the H-abstraction reaction increases with increasing collision energy (Ecoll). Scattering angle, initial attack angle, and product relative translational energy distributions indicate that the mechanism changes with the collision energy from indirect/rebound to direct stripping. The distribution of initial attack angles shows a clear preference for methyl group attack but with different angles at different Ecoll values. Post-reaction energy distributions show that the energy transfer is biased toward the products' relative translational energy instead of their internal energy. Rotational and vibrational energy have about the same amount of contribution to the internal energy in the case of both products (HCl and CH2CN), i.e., both of them are formed with high rotational excitations. HCl is produced mostly in the ground vibrational state, while a notable fraction of CH2CN is formed with vibrational excitation. [ABSTRACT FROM AUTHOR]

In this study, peptides designed using fragments of an antifreeze protein (AFP) from the freeze-tolerant insect Tenebrio molitor, TmAFP, were evaluated as inhibitors of clathrate hydrate formation. It was found that these peptides exhibit inhibitory effects by both direct and indirect mechanisms. The direct mechanism involves the displacement of methane molecules by hydrophobic methyl groups from threonine residues, preventing their diffusion to the hydrate surface. The indirect mechanism is characterized by the formation of cylindrical gas bubbles, the morphology of which reduces the pressure difference at the bubble interface, thereby slowing methane transport. The transfer of methane to the hydrate interface is primarily dominated by gas bubbles in the presence of antifreeze peptides. Spherical bubbles facilitate methane migration and potentially accelerate hydrate formation; conversely, the promotion of a cylindrical bubble morphology by two of the designed systems was found to mitigate this effect, leading to slower methane transport and reduced hydrate growth. These findings provide valuable guidance for the design of effective peptide-based inhibitors of natural-gas hydrate formation with potential applications in the energy and environmental sectors. [ABSTRACT FROM AUTHOR]

The lifetime of a hydrogen bond between water and dimethyl sulfoxide (DMSO) is found to be considerably longer than that between two water molecules in neat water. This is counter-intuitive because the charge on the oxygen in DMSO is considerably less than that in water. Additionally, the strength of the water–dimethyl sulfoxide (w–D) hydrogen bond is found to be strongly composition dependent; the lifetime of the hydrogen bond is ten times larger at 30% than at very low concentrations. Using computer simulations, we perform microscopic structural and dynamic analysis to find that these anomalies arise at least partly from an "action-at-a-distance" effect where the attraction between the hydrophobic methyl groups results in the self-aggregation of DMSO molecules that "cages" both the rotational and linear motions of the molecules involved. This is reflected in the observed strong correlation of the lifetime with the local coordination number of the associated methyl groups. The elongated w–D h-bond lifetime causes a slowdown of collective dynamics and affects the lifetime of the w–w h-bond. This nonlinear feedback mechanism explains the strong composition dependence of viscosity and is anticipated to play a dominant role in many self-assemblies. Furthermore, the w–D hydrogen bond breaking mechanism changes from low to high DMSO concentration, a phenomenon not anticipated a priori. We introduce a new order parameter-based free energy surface of the bond breaking pathway. A two-dimensional transition state rate theory calculation is performed for the lifetime of the w–D h-bond that is found to be semi-quantitatively accurate. [ABSTRACT FROM AUTHOR]

We investigated the rotational spectrum of 2,5-dimethylfluorobenzene containing coupled large amplitude motions of two methyl groups in the frequency range from 2 to 26.5 GHz using a pulsed molecular jet Fourier transform microwave spectrometer. The internal rotation of two inequivalent methyl groups with low torsional barriers (around 16 and 226 cm−1) causes splittings of all rotational transitions into quintets with separations of up to hundreds of MHz between the torsional components. Spectral analysis and modeling of the observed splittings were performed using the programs XIAM and BELGI-Cs-2Tops, whereby the latter achieved measurement accuracy. The methyl internal rotation can be used to examine the electronic and steric environments around the methyl group because they affect the methyl torsional barrier. Electronic properties play a particularly important role in aromatic molecules in the presence of a π-conjugated double bond system. The experimental results were compared with those of quantum chemistry. Benchmark calculations resulted in the conclusion that the B3LYP-D3BJ/6-311++G(d,p) level of theory can be recommended for predicting rotational constants to guide the microwave spectral assignment of dimethylfluorobenzenes in particular and toluene derivatives in general. [ABSTRACT FROM AUTHOR]

In this study, the total ion yield near-edge x-ray absorption fine structure spectra of four similar peptoid molecules, which differ in the numbers and positions of methyl groups, were investigated experimentally and theoretically. At each excitation energy, the intensity and branching ratio of each ionic product were measured. At a few resonant excitation energies, a specific dissociation of the C–CO bond at the nitrogen and oxygen K-edges and of the N–CO bond at the carbon K-edge was dominant, which correlated well with the predicted destination antibonding orbitals of the core electron excitation. These specific dissociation mechanisms of small peptoid molecules could provide insights into similar phenomena that occur in peptide molecules. [ABSTRACT FROM AUTHOR]

Irisquinone is a tumor radiotherapy sensitizer and has been found to have broad-spectrum antitumor activity in recent years. The current acquisition method of extracting and purifying from semen irisis has greatly limited its wide application and activity study deeply. In this work an efficient route for the synthesis of the irisquinone was investigated to solve the source of it. The target compound was synthesized by 5-step reactions to Wittig reaction, reduction, oxidation, Wittig reaction, and oxidation using 3,5-dimethoxycarboxaldehyde as the starting material with an overall yield of 48%. The key factors such as the ratio of raw materials, temperatures, solvents, reaction times, and types of base for the main reactions were optimized. In addition, the deprotection and reduction were completed with Pd/C catalytic simultaneously when compound 2 was synthesized from compound 1. In the last reaction, the 3,5-dimethoxybenzene moiety of compound 4 was directly oxidized to 6-methoxy-1,4-benzoquinone by K3 [Fe(CN)6 ]/H2 O2 without the need to selectively remove the methyl protecting group, which were the innovative points in the experimental route design of the irisquinone synthesis. This work has opened new perspectives for the artificial synthesis and the development of irisquinone. [ABSTRACT FROM AUTHOR]

exo‐6b2‐Methyl‐substituted pentabenzocorannulene (exo‐PBC‐Me) was synthesized by the palladium‐catalyzed cyclization of 1,2,3‐triaryl‐1H‐cyclopenta[l]phenanthrene. Its bowl‐shaped geometry with an sp3 carbon atom in the backbone and a methyl group located at the convex (exo) face was verified by X‐ray crystallography. According to DFT calculations, the observed conformer is energetically more favorable than the endo one by 39.9 kcal/mol. Compared to the nitrogen‐doped analogs with intact π‐conjugated backbones (see the main text), exo‐PBC‐Me displayed a deeper bowl depth (avg. 1.93 Å), redshifted and broader absorption (250–620 nm) and emission (from 585 to more than 850 nm) bands and a smaller optical HOMO–LUMO gap (2.01 eV). exo‐PBC‐Me formed polar crystals where all bowl‐in‐bowl stacking with close π ⋅ ⋅ ⋅ π contacts is arranged unidirectionally, providing the potential for applications as organic semiconductors and pyroelectric materials. This unusual structural feature, molecular packing, and properties are most likely associated with the assistance of the methyl group and the sp3 carbon atom in the backbone. [ABSTRACT FROM AUTHOR]

In X‐ray structures of the isomorphic mer‐[IrX3(THT)(CNXyl)2] (X=Cl 1, Br 2; THT=tetrahydrothiophene; Xyl=2,6‐Me2C6H3−) complexes, we revealed short intermolecular contacts between the C‐atom of an isocyanide methyl group and halide ligands of another molecule. Geometrical consideration of the X‐ray data and analysis of appropriate DFT studies allowed the attribution of these contacts to CMe⋅⋅⋅X−IrIII (X=Cl, Br) tetrel bond. Specifically, through the application of DFT calculations and various theoretical models, the presence of tetrel bonding interactions was validated, and the contribution of the CMe⋅⋅⋅X−IrIII interaction was assessed. The reinforcement of the tetrel bond upon the isocyanide coordination to iridium(III) is substantiated by molecular electrostatic potential (MEP) surface calculations. To distinguish the tetrel bonding characteristics of CMe⋅⋅⋅X−IrIII (X=Cl, Br) interactions from conventional hydrogen bonding, we employed multiple computational methodologies, including Natural Bond Orbital (NBO) analysis and Electron Localization Function (ELF) analysis. Additionally, Energy Decomposition Analysis (EDA) was applied to selected model systems to explore the underlying physical nature of these interactions. [ABSTRACT FROM AUTHOR]

DNMT1 is an essential DNA methyltransferase that catalyzes the transfer of methyl groups to CpG islands in DNA and generates a prominent epigenetic mark. The catalytic activity of DNMT1 relies on its conformational plasticity and ability to change conformation from an auto-inhibited to an activated state. Here, we present four cryo-EM reconstructions of apo DNMT1 and DNTM1: non-productive DNA, DNTM1: H3Ub2-peptide, DNTM1: productive DNA complexes. Our structures demonstrate the flexibility of DNMT1's N-terminal regulatory domains during the transition from an apo 'auto-inhibited' to a DNA-bound 'non-productive' and finally a DNA-bound 'productive' state of DNMT1. Furthermore, we address the regulation of DNMT1's methyltransferase activity by a DNMT1-selective small-molecule inhibitor and ubiquitinated histone H3. We observe that DNMT1 binds DNA in a 'non-productive' state despite the presence of the inhibitor and present the cryo-EM reconstruction of full-length DNMT1 in complex with a di-ubiquitinated H3 peptide analogue. Taken together, our results provide structural insights into the reaction cycle of DNMT1. [ABSTRACT FROM AUTHOR]

Functionalization of Si‐bound methyl group provides an efficient access to diverse organosilanes. However, the asymmetric construction of silicon‐stereogenic architectures by functionalization of Si‐bound methyl group has not yet been described despite recent significant progress in producing chiral silicon. Herein, we disclosed the enantioselective silylmethyl functionalization involving the aryl to alkyl 1,5‐palladium migration to access diverse naphthalenes possessing an enantioenriched stereogenic silicon center, which are inaccessible before. It is worthy to note that the realization of asymmetric induction at the step of metal migration itself remains challenging. Our study constitutes the first enantioselective aryl to alkyl 1,5‐palladium migration reaction. The key to the success is the discovery and fine‐tuning of the different substituents of α,α,α,α‐tetraaryl‐1,3‐dioxolane‐4,5‐dimethanol (TADDOL)‐based phosphoramidites, which ensure the enantioselectivity and desired reactivity. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate the use of machine learning to optimize the continuous flow process of a crucial intermediate in the production of Nemonoxacin. Our focus is to achieve the good yield and enantioselectivity in the construction of chiral methyl group utilize the initial 29 experimental datasets and consider six important variables. Employing Single-Objective Bayesian optimization (SOBO), we achieved an impressive predicted yield of up to 89.7%, which is consistent with the experimental results, with a yield of 89.5%. Additionally, A Multi-Objective Bayesian Optimization (MOBO) algorithm, namely qNEHVI, to strike a balance between yield and enantioselectivity in the continuous flow system is applied. The algorithm's prediction, with a yield of 81.8% and enantioselectivity of 97.85%, was experimentally validated, yielding 83.8% and 97.2%, respectively. This study effectively demonstrates that Bayesian optimization is a powerful tool for optimizing the continuous process in the production of active pharmaceutical ingredients (APIs). [ABSTRACT FROM AUTHOR]

3,3,3-Trifluoro-1,2-propanediol undergoes complete defluorination in two distinct steps: first, the conversion into 3,3,3-trifluoropropionaldehyde catalyzed by adenosylcobalamin (coenzyme B 12 )-dependent diol dehydratase; second, non-enzymatic elimination of all three fluorides from this aldehyde to afford malonic semialdehyde (3-oxopropanoic acid), which is decarboxylated to acetaldehyde. Diol dehydratase accepts 3,3,3-trifluoro-1,2-propanediol as a relatively poor substrate, albeit without significant mechanism-based inactivation of the enzyme during catalysis. Optical and electron paramagnetic resonance (EPR) spectra revealed the steady-state formation of cob(II)alamin and a substrate-derived intermediate organic radical (3,3,3-trifluoro-1,2-dihydroxyprop-1-yl). The coenzyme undergoes Co–C bond homolysis initiating a sequence of reaction by the generally accepted pathway via intermediate radicals. However, the greater steric size of trifluoromethyl and especially its negative impact on the stability of an adjacent radical centre compared to a methyl group has implications for the mechanism of the diol dehydratase reaction. Nevertheless, 3,3,3-trifluoropropionaldehyde is formed by the normal diol dehydratase pathway, but then undergoes non-enzymatic conversion into acetaldehyde, probably via 3,3-difluoropropenal and malonic semialdehyde. [ABSTRACT FROM AUTHOR]

The preferential solvation parameters of atenolol in aqueous binary mixtures of propylene glycol (PG) were derived from reported molar solubility values after conversion to mole fractions by using the inverse Kirkwood–Buff integrals method. This drug is sensitive to preferential solvation effects in this binary system. The preferential solvation parameter by PG (δx1,3) is negative in water-rich mixtures but positive in mixtures of 0.20 < x1 < 1.00. It is conjecturable that hydrophobic hydration around the non-polar methyl and phenylene groups of this drug observable in water-rich mixtures could play a relevant role in drug solvation. Otherwise, in mixtures of 0.20 < x1 < 1.00, the preferential solvation by PG could be due to the acidic behaviour of atenolol. [ABSTRACT FROM AUTHOR]

Tetra‐cyano substituted naphthalene diimides (TCNDIs) with calculated LUMO of −5.2 eV, form one of the strongest electron‐acceptors known to date. However, the synthesis and isolation of this class of molecules remain challenging due to its reactivity emanating from its ultra‐electron‐deficiency. Herein we have established an improved synthetic methodology of TCNDIs with cost‐effective reagents and circumventing metallic catalysts. The synthesis is amenable to TCNDIs with the shortest axial alkyl groups, i. e. methyl group and also longer alkyl chains. We also gained insight on how axial alkyl chain lengths influence electron‐deficiency, Meisenheimer complex formation, reactivity, and charge‐transfer of TCNDIs from computation, spectroscopy, and electrochemical studies. The TCNDIs with Me/Et axial groups were found to be more susceptible to moist solvents vis‐à‐vis the TCNDIs with longer alkyl groups. The single crystal structures of the TCNDIs show infinitely π‐stacked structure, and a new C=O ⋅ ⋅ ⋅ C≡N or C≡N ⋅ ⋅ ⋅ π motif is discerned. Finally, toluene‐mediated charge‐transfer properties of TCNDIs in the single crystals as well as in solution have been examined. [ABSTRACT FROM AUTHOR]

Herein, we demonstrate an Oxa‐Diels‐Alder reaction of 3‐trifluoroacetyl‐4‐methyl‐quinolin‐2(1H)‐one with aldehydes in the presence of a base to engineer the functionalized pyrano[3,4‐c]quinolones. This reaction proceeds through an in‐situ generated hetero dendralene intermediate and features perfect stereoselectivity on a wide range of substrates with excellent atom economy. The high electron‐withdrawing nature of CF3‐group is responsible for making the methyl group present in quinolone moiety more acidic to furnish the corresponding hetero dendralene intermediate. [ABSTRACT FROM AUTHOR]

Comprehensive Summary Photoinitiators of the oxime ester (OXE) or ketoxime ester (OXE‐CO) type can rapidly undergo N—O bond cleavage and generate free radicals to initiate photopolymerization under LED excitation, occupying an important position in the field of photocuring. However, the commercial OXEs, e.g., OXE 01 and 02 with λmax's at 326 and 344 nm, respectively, still do not well match the emission spectra of LEDs. Developing novel OXEs/OXE‐COs with high photosensitivity for long‐wavelength LEDs has great significance. Here, four new OXEs/OXE‐COs with nitro‐carbazole‐styrene conjugated chromophore were designed, synthesized, and used as photoinitiators. Results demonstrated that all photoinitiators had strong absorption within the UV–vis range (λmax: 381—392 nm, εmax: 8200—11500 M−1·cm−1). Molecular design of the oxime ester cleavage to produce a small volume methyl group and a methacryl group with an unsaturated double bond brings high activity and low migration, respectively, in one‐photon polymerization under 365—450 nm LEDs excitation. Moreover, OXEs/OXE‐COs with PETA exhibited a wide processing window, high resolution (line accuracy~100 nm) and good nano‐patterning capability under 780 nm femtosecond laser irradiation in two‐photon polymerization, indicating their great potential in 2D/3D microfabrication technologies. [ABSTRACT FROM AUTHOR]

This study investigates polyaniline (PANI) for its sensing characteristics for detecting acetaldehyde. Pristine PANI is further modified in two ways to improve its sensing capabilities: 1) addition of a side chain (i.e., two methyl groups) to form poly (2,5‐dimethylaniline), 2) addition of small amounts of metal oxide dopant (In2O3 in this case) to PANI. All the materials are evaluated for their sensing characteristics with respect to both sensitivity and selectivity. The sensitivity of PANI toward acetaldehyde is found to improve with both types of modification (i.e., poly (2,5‐dimethylaniline) and PANI doped with different wt.% of In2O3). However, upon evaluating selectivity toward acetaldehyde using binary and ternary gas mixtures, pristine PANI exhibited higher selectivity compared to its modified counterparts. [ABSTRACT FROM AUTHOR]

Introducing a methyl group into 1,3-dioxolane (DOL) to obtain a stable cyclic ether, 4-methyl-1,3-dioxolane (4-Me DOL), allows it to be used as an additive in LiPF6-based carbonate electrolytes. The addition of 4-Me DOL can form a stable SEI with good Li+ transport ability, which can simultaneously improve the rate capability and cycling performance of lithium metal batteries. [ABSTRACT FROM AUTHOR]

Associating molecular structure and mechanical properties is important for silicone rubber design. Although silicone rubbers are widely used due to their odourless, non-toxic, and high- and low-temperature resistance advantages, their application and development are still limited by their poor mechanical properties. The mechanical properties of silicone rubbers can be regulated by designing the cross-link density and cross-linking structure, and altering the molar contents of vinyl in the side groups of methyl vinyl silicone rubber (MVQ) leads to different cross-linking structures and cross-linking densities in the vulcanized rubber. Therefore, this study investigated the differences in molecular parameters and molecular chain structures of unprocessed MVQ rubbers with different vinyl contents. The results showed that MVQ rubbers with high vinyl contents were branched polymers, better facilitating the cross-linking reaction than MVQ rubbers with low vinyl contents. In addition, silicone rubbers with different vinyl contents were co-cross-linked to introduce an inhomogeneous cross-linked network in the silicone rubber to improve its mechanical properties. The cross-linked network properties were analysed by the Flory–Rehner model and Mooney–Rivlin plots, and it was found that the long chains in the sparsely cross-linked domains of the network favoured high elongation at break and the short chains in the densely cross-linked domains contributed to high modulus, which could satisfy the functions of reinforcing and toughening the rubber materials at the same time. It was also found by analysing the filler network and aggregate morphology that the inhomogeneous cross-linked network led to an improvement in the dispersion of silica in the rubber and a significant improvement in the mechanical properties of silicone rubber. [ABSTRACT FROM AUTHOR]

First case of regiospecific formation of indole fused with a triterpene scaffold is observed. Starting from 3‐oxo‐24‐nor‐allobetulin Fischer reaction with phenylhydrazine under the influence of weak acid catalyst led to 3H‐indole (indolenine) 4. This process was accompanied by a change in the configuration of the methyl group at C‐4 that was confirmed by x‐ray diffraction method. On the other hand, 3,2‐indole 5 was synthesized under the influence of strong acid catalyst (using phenylhydrazine hydrochloride in AcOH acid or phenylhydrazine in MeOH with a few drops of HCl). [ABSTRACT FROM AUTHOR]

Pure SnO2 and 1 at.% PdO–SnO2 materials were prepared using a simple hydrothermal method. The micromorphology and element valence state of the material were characterized using XRD, SEM, TEM, and XPS methods. The SEM results showed that the prepared material had a two-dimensional nanosheet morphology, and the formation of PdO and SnO2 heterostructures was validated through TEM. Due to the influence of the heterojunction, in the XPS test, the energy spectrum peaks of Sn and O in PdO–SnO2 were shifted by 0.2 eV compared with SnO2. The PdO–SnO2 sensor showed improved ethanol sensing performance compared to the pure SnO2 sensor, since it benefited from the large specific surface area of the nanosheet structure, the modulation effect of the PdO–SnO2 heterojunction on resistance, and the catalyst effect of PdO on the adsorption of oxygen. A DFT calculation study of the ethanol adsorption characteristics of the PdO–SnO2 surface was conducted to provide a detailed explanation of the gas-sensing mechanism. PdO was found to improve the reducibility of ethanol, enhance the adsorption of ethanol's methyl group, and increase the number of adsorption sites. A synergistic effect based on the continuous adsorption sites was also deduced. [ABSTRACT FROM AUTHOR]

Polydopamine (PDA) has garnered significant interest for applications in biosensors, drug delivery, and tissue engineering. However, similar polycatecholamines like polynorepinephrine (PNE) with additional hydroxyl groups and poly-α-methylnorepinephrine (PAMN) with additional hydroxyl and methyl groups remain unexplored in the biosensing domain. This research introduces three innovative biosensing platforms composed of ternary nanocomposite based on reduced graphene oxide (RGO), gold nanoparticles (Au NPs), and three sister polycatecholamine compounds (PDA, PNE, and PAMN). The study compares and evaluates the performance of the three biosensing systems for the ultrasensitive detection of Mycobacterium tuberculosis (MTB). The formation of the nanocomposites was meticulously examined through UV–Visible, Raman, XRD, and FT-IR studies with FE-SEM and HR-TEM analysis. Cyclic voltammetry and differential pulse voltammetry measurements were also performed to determine the electrochemical characteristics of the modified electrodes. Electrochemical biosensing experiments reveal that the RGO-PDA-Au, RGO-PNE-Au, and RGO-PAMN-Au-based biosensors detected target DNA up to a broad detection range of 0.1 × 10−8 to 0.1 × 10−18 M, with a low detection limit (LOD) of 0.1 × 10−18, 0.1 × 10−16, and 0.1 × 10−17 M, respectively. The bioelectrodes were proved to be highly selective with excellent sensitivities of 3.62 × 10−4 mA M−1 (PDA), 7.08 × 10−4 mA M−1 (PNE), and 6.03 × 10−4 mA M−1 (PAMN). This study pioneers the exploration of two novel mussel-inspired polycatecholamines in biosensors, opening avenues for functional nanocoatings that could drive further advancements in this field. [ABSTRACT FROM AUTHOR]

Copyright of China Rubber Industry is the property of Editorial Office of China Rubber Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The strategic installation of the "magic methyl" group at a certain location in lead compounds has become an important tool for medicinal chemists in the field of drug discovery. Both photochemistry and electrochemistry have witnessed an explosive resurgence in recent years and emerged as a cornerstone of modern organic chemistry. In this review, we conducted an extensive data mining of the literature and provide a comprehensive overview of the recent advancements in utilizing green photochemical and electrochemical methodologies for the incorporation of methyl groups, with specific emphasis on the methyl source, design strategies and reaction mechanisms. These research developments provide sustainable and broadly applicable tools to develop valuable methylated products with major prospects for the pharmaceutical industry. In addition, their applications in the late-stage functionalization of bioactive compounds are also demonstrated. [ABSTRACT FROM AUTHOR]

Facile transmetalation is observed from a d8 metal, platinum(II), to indium and gallium leading to the extrusion of methylated gallate and indate anions representing a rare case of the "reverse" transmetalation from a d8 metal to a main group metal. The Pt–Ga and Pt–In bonding in the bimetallic complexes was analyzed through bosonic and fermionic potentials, QTAIM, and NBO. [ABSTRACT FROM AUTHOR]

DFT calculations were performed for the methyl group transfer reaction between CH3Co (dmgBF2)py and PPh3Ni(Triphos). The reaction mechanism and its energetics were investigated. This reaction is relevant to the catalytic mechanism of the enzyme acetyl coenzyme A synthase. BP86 and PBE functionals and dispersion corrections were used. It was found that intermolecular interactions are very important for this reaction. The influence of the solvent on the reaction was studied. [ABSTRACT FROM AUTHOR]

Tetroxane derivatives are interesting drugs for antileishmaniasis and antimalaric treatments. The gas-phase thermal decomposition of 3,6,-dimethyl-1,2,4,5-tetroxane (DMT) and 3,3,6,6,-tetramethyl-1,2,4,5-tetroxane (acetone diperoxide (ACDP)) was studied at 493–543 K by direct gas chromatography by means of a flow reactor. The reaction is produced in the injector chamber at different temperatures. The resulting kinetics Arrhenius equations were calculated for both tetroxanes. Including the parent compound of the series 1,2,4,5-tetroxane (formaldehyde diperoxide (FDP)), the activation energy and frequency factors decrease linearly with the number of methyl groups. The reaction mechanisms of ACDP and 3,6,6-trimethyl-1,2,4,5-tetroxane (TMT) decomposition have been studied by means of the DFT method with the BHANDHLYP functional. Our calculations confirm that the concerted mechanism should be discarded and that only the stepwise mechanism occurs. The critical points of the singlet and triplet state potential energy surfaces (S- and T-PES) of the thermolysis reaction of both compounds have been determined. The calculated activation energies of the different steps vary linearly with the number of methyl groups of the methyl-tetroxanes series. The mechanism for the S-PES leads to a diradical O···O open structure, which leads to a C···O dissociation in the second step and the production of the first acetaldehyde/acetone molecule. This last one yields a second C···O dissociation, producing O2 and another acetone/acetaldehyde molecule. The O2 molecule is in the singlet state. A quasi-parallel mechanism for the T-PES from the open diradical to products is also found. Most of the critical points of both PES are linear with the number of methyl groups. Reaction in the triplet state is much more exothermic than the singlet state mechanism. Transitions from the singlet ground state, S0 and low-lying singlet states S1–3, to the low-lying triplet excited states, T1–4, (chemical excitation) in the family of methyl tetroxanes are also studied at the CASSCF/CASPT2 level. Two possible mechanisms are possible here: (i) from S0 to T3 by strong spin orbit coupling (SOC) and subsequent fast internal conversion to the excited T1 state and (ii) from S0 to S2 from internal conversion and subsequent S2 to T1 by SOC. From these experimental and theoretical results, the additivity effect of the methyl groups in the thermolysis reaction of the methyl tetroxane derivatives is clearly highlighted. This information will have a great impact for controlling these processes in the laboratory and chemical industries. [ABSTRACT FROM AUTHOR]

Ten isatin-based hydrazone derivatives were synthesized using two subseries, IA (isatin + acetophenone) and IB (isatin + benzaldehyde), and evaluated for their monoamine oxidases (MAOs) inhibitory activity. All the compounds showed stronger MAO-A inhibition than MAO-B, and the IB series showed more effective MAO-A inhibitory activity than IA series. Compound IB4 most potently inhibited MAO-A (half maximal inhibitory concentration IC50 = 0.015 µM), followed by IB3 (IC50 = 0.019 µM). On the contrary, compound IB3 showed the highest MAO-B inhibition (IC50 = 0.068 µM), followed by IB4 (IC50 = 1.87 µM). Compound IB3 and IB4 had low selectivity indices of 3.68 and 8.50, respectively. Structurally, the methyl group of IA series decreased the inhibition of both MAO-A and MAO-B. Among them, IB3 and IB4 (4-Cl and 4-Br in B-ring, respectively) showed higher MAO-A and MAO-B inhibition than the other substitutions. Inhibition constant Ki values of IB3 and IB4 for MAO-A were 0.0088 and 0.0063 µM, respectively, and those for MAO-B were 0.048 and 0.060 µM, respectively. IB3 and IB4 were competitive, reversible inhibitors of MAO-A and MAO-B. Molecular docking analysis predicted that IB3 and IB4 formed stable hydrogen bonds between Asn181 and the NH atom of isatin in the ligand-protein complex. Dynamic analysis revealed that IB3 and IB4 are stable with both MAO isoforms. These observations suggest IB3 and IB4 are potent and reversible MAO-A and MAO-B inhibitors and both compounds can be used as therapeutic agents for neurological disorders. [ABSTRACT FROM AUTHOR]

The histone deacetylases (HDACs) are being explored as a promising therapeutic target for the treatment of various diseases. Here, the synthesis of a series of pyrimidine‐based 1,3,4‐oxadiazoles, in which the oxadiazole scaffold is attached to the pyrimidine ring via a methyleneoxy spacer, is described and their HDAC inhibitory activity studied. The target compounds were synthesized by sequence of reactions involving O‐alkylation of 2‐(methylthio)pyrimidin‐4(3H)‐ones with ethyl 2‐bromoethanoate followed by oxidation of the 2‐methylthio group, displacement of the obtained 2‐methylsulfonyl group with amines, hydrazinolysis of the obtained ethyl (2‐amino‐substituted pyrimidin‐4‐yloxy)acetates to give the corresponding hydrazides and their cyclization under the treatment with ethyl O‐ethyl xanthate or carbonyldiimidazole to 1,3,4‐oxadiazole‐2(3H)‐thiones and 1,3,4‐oxadiazol‐2(3H)‐one, correspondingly. In addition, two 1,3,4‐oxadiazole‐2(3H)‐thiones were converted into (N3)‐morpholinomethyl derivatives by the Mannich reaction with formaldehyde and morpholine. The yields of intermediates and target compounds ranged from moderate to excellent. The synthesized compounds were characterized by 1H and 13C NMR spectra and HRMS data, their purity was controlled by TLC. The synthesized pyrimidine‐based 1,3,4‐oxadiazoles (18 compounds) were tested as inhibitors of the HDAC4 and HDAC8 isoforms and their inhibitory activity was compared with that of Vorinostat. Most of the oxadiazolethiones containing methyl group at the position 6 of the pyrimidine moiety were found to be more selective towards HDAC8, while oxadiazolethiones with propyl group in the pyrimidine ring were active against HDAC4. Among the tested compounds, 5‐((2‐(dibutylamino)‐6‐propylpyrimidin‐4‐yloxy)methyl)‐1,3,4‐oxadiazole‐2(3H)‐thione (48) was found to have the strongest inhibitory activity for HDAC4 isoform (IC50 = 4.2 μM vs. IC50 = 59 μM for Vorinostat) while 5‐((2‐(cyclopentylamino)‐6‐propylpyrimidin‐4‐yloxy)methyl)‐1,3,4‐oxadiazole‐2(3H)‐thione (50) was the most potent HDAC8 inhibitor (IC50 = 6.8 μM). [ABSTRACT FROM AUTHOR]

Genomic DNA methylation patterns play a crucial role in the developmental processes of plants and mammals. In this study, we aimed to investigate the significant effects of epigenetic mechanisms on the development of soybean seedlings and metabolic pathways. Our analyses show that 5‐azaC‐treatment affects radicle development from two Days After Imbibition (DAI), as well as both shoot and root development. We examined the expression levels of key genes related to DNA methylation and demethylation pathways, such as DRM2, which encodes RNA‐directed DNA Methylation (RdDM) pathway, SAM synthase, responsible for methyl group donation, and ROS1, a DNA demethylase. In treated seedling roots, we observed an increase in DRM2 expression and a decrease in ROS1 expression. Additionally, 5‐azaC treatment altered protein accumulation, indicating epigenetic control over stress response while inhibiting nitrogen assimilation, urea cycle, and glycolysis‐related proteins. Furthermore, it influenced the levels of various phytohormones and metabolites crucial for seedling growth, such as ABA, IAA, ethylene, polyamines (PUT and Cad), and free amino acids, suggesting that epigenetic changes may shape soybean responses to pathogens, abiotic stress, and nutrient absorption. Our results assist in understanding how hypomethylation shapes soybean responses to pathogens, abiotic stress, and nutrient absorption crucial for seedling growth, suggesting that the plant's assimilation of carbon and nitrogen, along with hormone pathways, may be influenced by epigenetic changes. [ABSTRACT FROM AUTHOR]

Two 3-(p-substituted phenyl)-3a,8a-dihydro-4H-cyclohepta[d]isoxazoles were synthesized by 1,3-dipolar cycloaddition of the corresponding nitrile oxides with cycloheptatriene. Two endoperoxides were synthesized as facially selective and single products in high yields (93%--95%) from the reactions of isoxazole derivatives with singlet oxygen. The exact configurations of the endoperoxide with a methyl group in the phenyl ring and the diol synthesized from it were confirmed by X-ray analysis. To elucidate the mechanism, the formation energy of the endoperoxide was investigated by simulations using the software package Gaussian 09 and density functional theory calculations via the M06-2X/6-311+G(d,p) level method in dichloromethane. The results were consistent with experimental findings showing the formation of isoxazole products. [ABSTRACT FROM AUTHOR]

Chalcogen bonds (ChB) are moderately strong, directional, and specific non‐covalent interactions that have garnered substantial interest over the last decades. Specifically, the presence of two σ‐holes offers great potential for crystal engineering, catalysis, biochemistry, and molecular sensing. However, ChB applications are currently hampered by a lack of methods to characterize and control chalcogen bonds. Here, we report on the influence of various substituents (halogens, cyano, and methyl groups) on the observed self‐complementary ChB networks of 2,1,3‐benzoselenadiazoles. From molecular electrostatic potential calculations, we show that the electrostatic surface potentials (ESP) of the σ‐holes on selenium are largely influenced by the electron‐withdrawing character of these substituents. Structural analyses via X‐ray diffraction reveal a variety of ChB geometries and binding modes that are rationalized via the computed ESP maps, although the structure of 5,6‐dimethyl‐2,1,3‐benzoselenadiazole also demonstrates the influence of steric interactions. 77Se solid‐state magic‐angle spinning NMR spectroscopy, in particular the analysis of the selenium chemical shift tensors, is found to be an effective probe able to characterize both structural and electrostatic features of these self‐complementary ChB systems. We find a positive correlation between the value of the ESP maxima at the σ‐holes and the experimentally measured 77Se isotropic chemical shift, while the skew of the chemical shift tensor is established as a metric which is reflective of the ChB binding motif. [ABSTRACT FROM AUTHOR]

For the first time, the oxidative polymerizations of o/m-anisidines and o-toluidine were carried out by ammonium peroxydisulfate in organic medium. According to the results of UV–Vis, 1H NMR and IR spectral methods the structures of the synthesized poly(o-anisidine) coincide with emeraldine base. Formation of dihydrobenzoxazole units was shown for poly(m-anisidine), which lowers the amount of both quinonediimine and methoxy groups in polymer. Obtained polymers show enhanced solubility in organic solvents. Thermal analysis shows that at 800 °C polyanisidines lost only 48% of their initial weight. Room temperature conductivity measurements show correspondingly 2.5 × 10−1 S/cm and 9 × 10−3 S/cm values for poly(o-anisidine) and poly(o-toluidine) when doped with inorganic acids. The ionization potential and electron affinities of obtained polymers were estimated by cyclic voltammograms. [ABSTRACT FROM AUTHOR]

The extraction of Np4+ was studied by a series of N-pivot tripodal diglycolamides, with varying substituents (alkyl groups with varying branching and chain length) and varying spacer length, dissolved in an ionic liquid, i.e. [C4mim][Tf2N]. Out of a series of four ligands, LI (propylene spacer) and LII (ethylene spacer) differ only in the spacer length connecting the three diglycolamide units with the tripodal N platform. While LII – LIV have the same spacer length (ethylene spacer), but LII has a hydrogen atom, LIII has methyl group, and LIV has isopropyl group as a substituent at the amidic N atom close to the central N atom. A reversal extraction mechanism of Np4+ was observed when the spacer chain length reduced from a propylene group in LI to an ethylene group in LII – LIV. While a cation-exchange mechanism was observed in case of LI, a solvation extraction mechanism was seen for the other three ligands with the extracted species being Np(NO3)2(L)2+ for LI, and [Np(NO3)4·L] for LII – LIV. The extraction efficiencies of Np4+ with LII – LIV were significantly affected by the nature of the alkyl substituents and follow the order: LII > LIII > LIV. This trend in the extraction pattern affirms that the alkyl substitution at the amidic N atom creates steric strain in the ligand while complexing with the metal ion. [ABSTRACT FROM AUTHOR]

The aryl diester compound, 2-methyl-1,4-phenylene bis(3,5-dibromobenzoate), C21H12Br4O4, was synthesized by esterification of methyl hydroquinone with 3,5-dibromobenzoic acid. A crystalline sample was obtained by cooling a sample of the melt (m.p. = 502 K/DSC) to room temperature. The molecular structure consists of a central benzene ring with anti-3,5-dibromobenzoate groups symmetrically attached at the 1 and 4 positions and a methyl group attached at the 2 position of the central ring. In the crystal structure (space group P1), molecules of the title aryl diester are located on inversion centers imposing disorder of the methyl group and H atom across the central benzene ring. The crystal structure is consolidated by a network of C--H...Br hydrogen bonds in addition to weaker and offset interactions involving the central benzene rings as well as the rings of the attached 3,5-dibromobenzoate groups. [ABSTRACT FROM AUTHOR]

The molecular structure of a crystalline monolayer of hydrocarbon chains was modeled and studied via computer simulation using the Metropolis Monte Carlo algorithm at a temperature T = 300 K. The only interactions in this system occur through Lennard‐Jones dispersion forces and short‐range atom‐atom repulsion. The intent was to establish whether the chains were either rigidly extended or twisted via the thermal formation of gauche bonds and apply the results to understand observations made on two possible oleogelators: triacontane and stearic acid. Specifically, we aimed to understand if their observed crystalline monolayer thicknesses are due to gauche‐bond‐shortened hydrocarbon chains oriented perpendicular to the monolayer surface, or to fully extended rigid chains oriented at a tilt angle with respect to the surface. The results showed that crystals of hydrocarbon chains did not include significant gauche bonds, so that all molecules were rigidly extended, thus explaining the experimental data previously reported. Accordingly, TC and SA dimer molecules are packed in crystalline multilayers with tilt angles in relation to the methyl group plane. [ABSTRACT FROM AUTHOR]

A series of novel 2‐(2‐pyridyl)quinazoline luminophores containing a donor aryl fragment at position 4 and methyl or methoxy groups at benzene ring has been synthesized by efficient three‐step route. The linear optical properties have been studied by UV/Vis absorption and photoluminescence spectra in two solvents. We revealed that introduction of additional methyl group or the replacement of methyl substituents with methoxy ones lead to sequentially shift of absorption and emission maximum to blue region. 9H‐Carbazol‐9‐yl‐containing derivative is characterized by hypsochromically shifted absorption band compared to its NEt2 and NPh2 counterparts. Unlike 9H‐carbazol‐9‐yl‐derivative, Et2N‐ and Ph2N‐bearing quinazolines demonstrate considerable decrease in quantum yield values when going from toluene to MeCN. Solvatochromic properties have been explored, the pronounced bathochromic shift was observed in fluorescence spectra with the increase of solvents polarity. Moreover, the compounds show significant shift of emission band with the increase of water fraction in DMSO/H2O mixture. Two‐photon optical properties have been also studied, the two‐photon absorption cross‐sections in MeCN and toluene reached 120 GM and 210 GM, respectively. The presence of additional methyl group has little impact on δTPA value, while introduction of methoxy substituents dramatically decreases TPA cross sections. Additionally, a quantum‐chemical calculations of synthesized compounds were performed to support the experimental data. [ABSTRACT FROM AUTHOR]

Thermal atomic layer etching (ALE) is one promising method to achieve atomic level precision and high conformality over three-dimensional structures that can further enable the manufacturing of gate-all-around devices. Initially, an ALE process using CF4/NH3/Ar remote plasma exposure followed by infrared (IR) annealing was studied on SiCO films. The process showed self-limiting behavior and achieved an etch per cycle (EPC) of 0.2 nm/cycle. To increase the EPC, an O2 remote plasma exposure step was added before the CF4/NH3/Ar plasma exposure step in the ALE cycle. The process achieved an EPC of 1.0 nm/cycle. Measurements of the EPC of the SiCO film showed self-limiting behavior in both the O2 and CF4/NH3/Ar steps. X-ray photoelectron spectroscopy results showed an increase in atomic concentration (AC) of oxygen while the AC of carbon decreased following the exposure of the film to an O2 remote plasma. The results indicate that methyl groups (-CH3) in the top layers of the film are being replaced by hydroxyl (-OH) groups and Si-O-Si bonding. The N1s spectrum showed the formation of an ammonium fluorosilicate (NH4)2SiF6-based surface-modified layer following exposure to a CF4/NH3/Ar remote plasma. IR annealing of the film showed desorption of the ammonium fluorosilicate surface-modified layer and the return to an as grown SiCO film surface composition. [ABSTRACT FROM AUTHOR]

Terahertz molecular motions are often probed by high-frequency molecular oscillators in different types of non-linear vibrational spectroscopy. Recently developed two-dimensional terahertz-infrared-visible spectroscopy allows direct measuring of this coupling and, thus, obtaining site-specific terahertz vibrational spectrum. However, these data are affected by the intensity and phase of the employed laser pulses. In this work, we develop a method of extracting sample response—representing solely physical properties of a material—from experimental spectra. Using dimethyl sulfoxide as a model molecule to verify this method, we measure the coupling between C–H stretch vibration of its methyl groups and terahertz intramolecular twist and wagging modes. [ABSTRACT FROM AUTHOR]

This article reports an efficient and practical microwave-assisted MMPP-promoted synthesis of novel pyrazolyl sulfones from the corresponding 4-(alkyl/cycloalkylthio)-1H-pyrazoles. The reaction of 4-(alkyl/cycloalkylthio)-1H-pyrazoles with magnesium bis(monoperoxyphthalate)hexahydrate (MMPP) as an oxidizing agent afforded the corresponding 4-(alkyl/cycloalkylsulfonyl)-1,3-disubstituted-1H-pyrazoles in 85–95% yield. This method's benefits include its straightforward operation, simple workup, and use of an inexpensive, halogen-free MMPP oxidant that is easy to use and reasonably stable. All synthesized pyrazolyl sulfones were examined against bacterial and fungal strains, and notable antimicrobial activity was demonstrated by a few of the compounds. In order to investigate the prospect of connecting compounds with the highest yield and antimicrobial activity with their opto-electronic properties, time-resolved photoluminescence investigations for compounds 5a, 5b, and 5d were conducted. The tunable spectrum was observed in the micro-second time domain in all three cases, with fluorescent lifetime found higher in the compound having methyl group, intermediate with phenyl group, and lowest with the p-nitrophenyl group. Our procedures will encourage additional research into the valuable properties of pyrazolyl sulfones now that they are widely available with the structural complexity illustrated here. [ABSTRACT FROM AUTHOR]

This study employs grand canonical Monte Carlo (GCMC) simulations to investigate the impact of functional group modifications (CH3, OH, NH2, and OLi) on the adsorption performance of CH4/N2 on Ni‐MOF‐74. The results revealed that functional group modifications significantly increased the adsorption capacity of Ni‐MOF‐74 for both CH4 and N2. The packed methyl groups in CH3‐Ni‐MOF‐74 create an environment conducive to CH4, leading to the highest CH4 adsorption capacity. The electrostatic potential distribution indicates that the strong electron‐donating effect introduced by the alkali metal Li results in the highest electrostatic potential gradient in Li‐O‐Ni‐MOF‐74, leading to the strongest adsorption of N2, this is unfavorable for CH4/N2 separation. At 1500 kPa the selectivity order of adsorbents for mixed gases was as follows: CH3‐Ni‐MOF‐74 > NH2‐Ni‐MOF‐74 > OH‐Ni‐MOF‐74 > Ni‐MOF‐74 > Li‐O‐Ni‐MOF‐74. This study highlights that CH3‐Ni‐MOF‐74 possesses optimal CH4 selectivity and adsorption performance. Given the current lack of research on functionalized MOF‐74 for the separation of CH4 and N2, the findings of this study will serve as a theoretical guide and provide references for the applications of CH4 adsorption and CH4/N2 separation. [ABSTRACT FROM AUTHOR]

This article discusses the development of a nickel-catalyzed hydroalkynylation reaction of 1,3-dienes with simple alkynes. The researchers used a Xantphos ligand to achieve regioselective hydroalkynylation, producing a variety of allylic alkyne products. They optimized the reaction conditions by adding water, which increased the yield of the desired product. The method demonstrated excellent functional-group tolerance and a wide substrate scope for alkynes. The researchers also proposed a mechanism for the reaction based on previous studies. Further research will focus on asymmetric variants, expanding the reaction scope, and exploring synthetic applications. [Extracted from the article]

The aim of this study was to obtain new halolactones with a gem-dimethyl group in the cyclohexane ring (at the C-3 or C-5 carbon) and a methyl group in the lactone ring and then subject them to biotransformations using filamentous fungi. Halolactones in the form of mixtures of two diasteroisomers were subjected to screening biotransformations, which showed that only compounds with a gem-dimethyl group located at the C-5 carbon were transformed. Strains from the genus Fusarium carried out hydrolytic dehalogenation, while strains from the genus Absidia carried out hydroxylation of the C-7 carbon. Both substrates and biotransformation products were then tested for antimicrobial activity against multidrug-resistant strains of both bacteria and yeast-like fungi. The highest antifungal activity against C. dubliniensis and C. albicans strains was obtained for compound 5b, while antimicrobial activity against S. aureus MRSA was obtained for compound 4a. [ABSTRACT FROM AUTHOR]

Nickel‐catalyzed cross‐electrophile coupling reactions of two aliphatic alcohol derivatives remain a challenge. Herein, we report a nickel‐catalyzed reductive methylation reaction of aliphatic mesylates with methyl tosylate. This reaction provides straightforward access to compounds bearing aliphatic methyl groups from alkyl alcohol derivatives. Isotopically labelled substrates and reagents can be employed in the reaction to provide perdeuterated and 13C‐labelled products. This transformation can be achieved by employing stoichiometric Mn reductant or electrochemically. Additionally, mechanistic experiments show that alkyl iodides are key intermediates in the transformation which undergo a stereoablative reaction via radical intermediates. [ABSTRACT FROM AUTHOR]

Scalable methods for improving the performance and stability of a field-effect transistor (FET) based on two-dimensional materials are crucial for its real applications. A scalable method of encapsulating the exfoliated MoS2 on the SiO2/Si substrate by hexamethyldisilazane (HMDS) is explored here for reducing the influence of interface traps and ambient contaminants. This leads to 25 times reduction in trap density, three times decrease in subthreshold swing, three times increase in the peak field-effect mobility, and a drastic reduction in hysteresis. This performance remains nearly the same after several weeks of ambient exposure of the device. This is attributed to the superhydrophobic nature of HMDS and the SiO2 surface hydrophobization by the formation of covalent bonds between the methyl groups of HMDS and silanol groups of SiO2. [ABSTRACT FROM AUTHOR]

In nature, hydrogen bonding is a common physical occurrence that has a significant impact on the surroundings of anthocyanins. Water molecules will create hydrogen bonds with anthocyanin molecules in various configurations, but the characteristics of these hydrogen bonds will change. Varied hydrogen bonding characteristics have varied impacts on solvent solutions. This research analyzes the differences in hydrogen bonding qualities caused by different methyl structures, as well as the underlying explanations. In this study, the cyanidin and peonidin structures of anthocyanin molecules were calculated in various stable hydrogen bond configurations using the density functional theory B3LYP/6‐31G(d,p), combined with information from the infrared spectroscopy spectrum, atoms in molecules analysis, interaction energy E, and intermolecular hydrogen bond length. The hydrogen bond structure that is the most stable is determined by analyzing it, as well as the effects of replacing the hydroxyl group with a methyl group and any potential underlying causes. Future anthocyanins research can benefit from the precise theoretical reference that this study can offer. [ABSTRACT FROM AUTHOR]

In this work, the reactions of nonacarbonyldiiron with 8‐alkynyloxyquinoline ligands (L1‐L3) and their resultant iron carbonyl complexes (1a, 1b, 2, and 3) are described. The complexes including the ligands were fully characterized by using a variety of spectroscopic techniques. The four complexes were also crystallographically determined. In the reactions, the quinoline N atom underwent cyclization to form a quinolinium skeleton while the C‐H bond of the quinoline at position 2 or the substituted methyl group was cleaved to form Fe‐C bond(s). Meanwhile, the alkynyl triple bond was reduced to a single bond (1a) or double bonds (1b, 2, and 3) to further coordinate the iron in σ‐bonds or η‐bonds. Particularly, pathways of hydrogenation (1a and 2) and/or dehydrogenation (1b and 3) were accompanied by the reactions. Moreover, the oxidation states of the iron centers in these complexes were identified through analyses of their bond formation, FTIR and NMR spectroscopic signals (1H NMR and DEPT‐135) in combination with their diamagnetic nature, that is, iron (0) for 2 and iron (I) for the rest of the diiron complexes. [ABSTRACT FROM AUTHOR]

The reaction of lithium hexa­methyl­disilyl­amide, [Li{N(Si(CH3)3)2}] (LiHMDS), with 4,4-dimethyl-2-phenyl-2-oxazoline (Phox, C11H13NO) in hexane produced colourless crystals of bis­(4,4-dimethyl-2-phenyl-2-oxazoline-κN)(hexa­methyl­disilyl­amido-κN)lithium, [Li(C6H18NSi2)(C11H13NO)2] or [Li{N(Si(CH3)3)2}(Phox)2] in high yield (89%). Despite the 1:1 proportion of the starting materials in the reaction mixture, the product formed with a 1:2 amide:oxazoline ratio. In the unit cell of the C2/c space group, the neutral mol­ecules lie on twofold rotation axes coinciding with the Li—N(amide) bonds. The lithium(I) centre adopts a trigonal–planar coordination geometry with three nitro­gen donor atoms, one from the HMDS anion and two from the oxazolines. All ligands are monodentate. In the phenyl­oxazoline units, the dihedral angle defined by the five-membered heterocyclic rings is 35.81 (5)°, while the phenyl substituents are approximately face-to-face, separated by 3.908 (5) Å. In the amide, the methyl groups assume a nearly eclipsed arrangement to minimize steric repulsion with the analogous substituents on the oxazoline rings. The non-covalent inter­actions in the solid-state structure of [Li{N(Si(CH3)3)2}(Phox)2] were assessed by Hirshfeld surface analysis and fingerprint plots. This new compound is attractive for catalysis due to its unique structural features. [ABSTRACT FROM AUTHOR]

The present study is focused on the use of cubic metal-organic frameworks-5 (MOF-5) and its functionalized form in the removal of phenolic pollutants by molecular dynamics (MD) and Well-tempered metadynamics (WTMD) simulation methods. It was found that the adsorption mechanism of MOF-5s/phenolic compounds is mostly due to the van der Waals and π–π interactions. However, electrostatic and hydrogen bond (HB) interactions also play a significant role in removing phenolic pollutants by MOF-5 and its functionalized form. The results show that the fluorine functional group (F-MOF-5) increases the adsorption capacity of phenol compounds on the adsorbent surface. By functionalizing the MOF-5 with a methyl functional group (CH3-MOF-5), the adsorption strength decreases. The WTMD calculation confirmed that at the most stable state, the free energy (FE) value of system II (the most stable system in functionalized systems with –F functional group) is about −289.528 kJ mol−1. This value is ~5.781 and 35.514 kJ mol−1 more negative than the FE of the I and III systems (the most stable systems in the pristine and CH3-MOF-5/pollutant systems, respectively). Altogether, the results indicate that F-MOF-5 can be considered a more suitable adsorbent than MOF-5 and CH3-MOF-5 for phenolic pollutants removal from the environment for more assessment. [ABSTRACT FROM AUTHOR]

Recently, various carbazole‐based self‐assembled monolayers (SAMs) have been investigated for use in the hole transport layer (HTL) of perovskite solar cells (PSCs). In particular, [4‐(3,6‐dimethyl‐9H‐carbazol‐9‐yl)butyl] phosphonic acid (Me‐4PACz) is attracting attention as an HTL for high‐efficiency PSC due to its potential for high open‐circuit voltage (VOC) and fill factor (FF). However, Me‐4PACz has strong hydrophobicity due to its methyl group (–CH3) and long alkyl chain (C4H8), which makes it difficult to deposit a high‐quality perovskite layer on top of conventionally coated Me‐4PACz. In this study, to overcome these limitations, a new SAM deposition method based on a vacuum‐assisted deposition (VD) process is attempted. As a result, a uniform perovskite layer is deposited on top of Me‐4PACz through a very simple VD process, achieving 20.31% efficiency, which is not only close to the highest efficiency among Me‐4PACz‐based PSCs, but also improved long‐term stability of the device. It is believed that the findings of this study can be a cornerstone for using SAM‐based HTL with high hydrophobicity in the future. [ABSTRACT FROM AUTHOR]