A „Magic Mushroom“ Multi‐Product Sesquiterpene Synthase

Posted on 12 September 2023 by

Shrooms going terpenoid: The sesquiterpene synthase CubA of the “magic mushroom” Psilocybe cubensis was identified as a multi-functional enzyme producing cubebol, β-copaene, and various other mono-, bi-, and tricyclic sesquiterpenes or -terpenoids. As related enzymes are encoded in numerous Psilocybe species, our results provide further insight into the true metabolic diversity of this genus.

Abstract

Psilocybe “magic mushrooms” are chemically well understood for their psychotropic tryptamines. However, the diversity of their other specialized metabolites, in particular terpenoids, has largely remained an open question. Yet, knowledge on the natural product background is critical to understand if other compounds modulate the psychotropic pharmacological effects. CubA, the single clade II sesquiterpene synthase of P. cubensis, was heterologously produced in Escherichia coli and characterized in vitro, complemented by in vivo product formation assays in Aspergillus niger as a heterologous host. Extensive GC-MS analyses proved a function as multi-product synthase and, depending on the reaction conditions, cubebol, β-copaene, δ-cadinene, and germacrene D were detected as the major products of CubA. In addition, mature P. cubensis carpophores were analysed chromatographically which led to the detection of β-copaene and δ-cadinene. Enzymes closely related to CubA are encoded in the genomes of various Psilocybe species. Therefore, our results provide insight into the metabolic capacity of the entire genus.

Benchmarking boron cluster calculations: Establishing reliable geometrical and energetic references for Bn (n = 1–4)

Posted on 12 September 2023 by

Abstract

Using full configuration interaction (FCI) and multi-reference configuration interaction methods (MRCI), reliable geometrical and energetic references for B_n (n = 1–4) clusters were established. The accuracy of the computed results was confirmed by comparison with available experimental data. Benchmark calculations indicated that B97D3, B97D, VSXC, HCTH407, BP86 and CCSD(T) methods provided reasonable results for structural parameters, with mean absolute error (MAEs) within 0.020 Å. Among the tested density functional theory (DFT) methods, the VSXC functional showed the best performance in predicting the relative energies of B₁B₄ with a MAE of 12.8 kJ mol⁻¹. Besides, B1B95, B971, TPSS, B3LYP, and BLYP functionals exhibited reasonable performance with MAE values of less than 15.0 kJ mol⁻¹. T ₁ diagnostic values between 0.035 and 0.109 at the CCSD(T) level revealed strong correlations in B₂B₄ clusters, highlighting the need for caution in using CCSD(T) as an energy reference for small boron clusters. The methods of CCSDT, CCSDT(Q) and CCSDT[Q], which incorporate three-electron and four-electron excitations, effectively improved the accuracy of the energy calculations.

Gemini surfactant‐stabilized Pd nanoparticles: Synthesis, characterization, and catalytic application in the reduction and reductive acetylation in the water solvent

Posted on 12 September 2023 by nPranshu K. Gupta, nAnkur Srivastava, nKalluri V.S. Ranganathn

The organogels have been prepared using long-chain gemini surfactants. Their rheological properties such as amplitude sweeping and viscosity shear profile have been studied. Further reductive acetylation was carried out in an aqueous medium using Pd NPs stabilized by organogels.

A series of Gemini surfactants (GSs) were prepared by reacting alkyl bromides with N,N,N′,N′-tetramethyl ethylenediamine. Various alkyl bromides used in for the preparation of GSs are 1,3-dibromo ethane, 1,3-dibromoethane, 1-Bromohexane, 1-Bromooctane, 1-Bromooctadecane and 1-Bromooctadodecane. Different solvents and temperatures were investigated for the formation of gels of prepared GSs. Among all, 1-Bromooctane, 1-Bromooctadecane-derived GSs formed organogels. Thus, synthesized long-chain organogels have been used to stabilize Pd NPs. The Pd NPs formation initially confirmed through Ultraviolet-visible, Scanning Electron Microscopy, and Atomic Force Micrograph studies. Later Fourier Tansform Infra Red, Thermo Gravimetric Analysis, and Zeta potential studies were also carried out to understand their properties extensively. The Pd NPs stabilized by GSs have been identified as a potential catalyst in the reductive N-acetylation of nitroaromatics at room temperature. The N-acetylated products were obtained in good yields in an aqueous medium. In addition, the potentiality of our catalyst has been also evaluated in the reduction of nitroaromatics in an aqueous medium, which is a green protocol. Further, the semi-empirical geometry optimizations of active GS gel confirmed the dihedral angle of 59° in between the two octyl moieties calculated from computational studies. The rheological properties such as amplitude sweeping, viscosity shear profile of the gel have also been studied.

Electrocatalytic Reduction of (Hetero)Aryl Halides in a Proton‐Exchange Membrane Reactor and its Application for Deuteration

Posted on 12 September 2023 by

We developed an electrocatalytic reduction of (hetero)aryl halides to substitute the halogeno groups to protons using a proton exchange membrane (PEM) reactor. Taking advantage of this transformation, deuterodehalogenation of (hetero)aryl bromides, which forms mono-deuterated (hetero)aryls, was demonstrated using heavy water as a deuterium source. The deuteration reaction was able to be optimized by Bayesian.

Abstract

We developed an electrocatalytic reduction of (hetero)aryl halides under mild conditions using a proton exchange membrane (PEM) reactor. This approach allows substituting the halogeno groups on the aryl rings to protons by water and electron. Taking advantage of this transformation, deuterodehalogenation of (hetero)aryl halides, which forms mono-deuterated (hetero)aryls, was demonstrated using heavy water as a deuterium source. The current efficiency and deuterium ratio could be increased by the conditions optimized by machine-learning method, Bayesian optimization.

Cerium(IV) Nitrate Complexes With Bidentate Phosphine Oxides

Posted on 12 September 2023 by

The formation, structures and thermal and solution stability of cerium(IV) complexes with bidentate phosphine oxides are reported. Complexes with flexible ligand architecture tend to be less stable showing decomposition to Ce(III) in solution. The decomposition products of the thermal decomposition in the solid state have been identified by infrared spectroscopy.

Abstract

The reactions between ceric ammonium nitrate, (NH₄)₂Ce(NO₃)₆, (CAN) and the bidentate phosphine oxides, 4,5-bis(diphenylphosphine oxide)-9,9-dimethylxanthene (L¹), oxydi-2,1-phenylene bis(diphenylphosphine dioxide) (L²), 1,2-bis(diphenylphosphino)ethane dioxide (L³) and 1,4-bis(diphenylphosphino)butane dioxide, L⁴ have been investigated. The crystal structures of the molecular Ce(NO₃)₄L¹ (1), and ionic [Ce(NO₃)₃L³ ₂][NO₃]⋅CHCl₃ (3), [Ce(NO₃)₃L³ ₂][NO₃] (4) and the polymeric [Ce(NO₃)₃L⁴ _1.5] [NO₃] (5) and the cerium(III) complex [Ce(NO₃)₂L¹ ₂][NO₃] (2) are reported. The thermal stability of the complexes has been examined by thermogravimetry with the gaseous decomposition products analysed by infrared spectroscopy. Evolution of CO₂ is found for both Ce(III) and Ce(IV) complexes with the later also forming NO₂. The formation of the complexes in solution has been studied by ³¹P NMR spectroscopy and further complexes [Ce(NO₃)₃L¹ ₂]⁺[NO₃]⁻ and [Ce(NO₃)₂L¹ ₃]²⁺2[NO₃]⁻ identified in CD₃CN solution. The complex (1) exists as a single molecular species in solution and is stable in dichloromethane whilst (3) decomposes on standing in both CD₂Cl₂ and CD₃CN to Ce(III) containing species. Complexes of L² have been identified by solution ³¹P NMR spectroscopy and these decompose in solution to give Ce(NO₃)₃L² ₂. This study represents the first structural characterisations of Ce(IV) complexes with bidentate phosphine oxides.

Smolyak Scheme for solving the Schrödinger equation: Application to Malonaldehyde in Full Dimensionality

Posted on 12 September 2023 by nDavid Lauvergnat, nAndré Nautsn

A quantum dynamics approach that combines a Smolyak scheme and curvilinear coordinates is described. It is applied to the computation of malonaldehyde tunneling splitting in full dimensionality.

Abstract

In 1963 Smolyak introduced an approach to overcome the exponential scaling with respect to the number of variables of the direct product size [S. A. Smolyak Soviet Mathematics Doklady, 4, 240 (1963)]. The main idea is to replace a single large direct product by a sum of selected small direct products. It was first used in quantum dynamics in 2009 by Avila and Carrington [G. Avila and T. Carrington, J. Chem. Phys., 131, 174103 (2009)]. Since then, several calculations have been published by Avila and Carrington and by other groups. In the present study, and to push the limit to larger and more complex systems, this scheme is combined with the use of an on-the-fly calculation of the kinetic energy operator and a Block-Davidson procedure to obtain eigenstates in our home-made Fortran codes, ElVibRot and Tnum-Tana. This was applied to compute the tunneling splitting of malonaldehyde in full dimensionality (21D) using the potential of Mizukami et al. [W. Mizukami, S. Habershon, and D.P. Tew, J. Chem. Phys. 141, 1443–10 (2014)]. Our tunneling splitting calculations, 21.7±0.3 cm⁻¹ and 2.9±0.1 cm⁻¹, show excellent agreement with the experimental values, 21.6 cm⁻¹ and 2.9 cm⁻¹ for the normal isotopologue and the mono-deuterated one, respectively.

Fabrication of Hyperbranched Photomechanical Crystals Composed of a Photochromic Diarylethene

Posted on 12 September 2023 by nMami Isobe, nDaichi Kitagawa, nSeiya Kobataken

The cover feature image shows the sublimation process of 1,2-bis(2,5-dimethyl-3-thienyl)perfluorocyclopentene on a concave surface of a spherical glass substrate, on which the branched hollow crystals are densely produced. These crystals can make the roles in moving and releasing the minute object during the bending behaviors by the irradiation with UV light according to the number and size of units of the hollow structures in them, which depend on the substrate curvature. More information can be found in the Research Article by Seiya Kobatake and co-workers.

Response of the mechanical and chiral character of ethane to ultra‐fast laser pulses

Posted on 12 September 2023 by

The ethane C1-C2 bond critical point (BCP) Hessian of ρ(r) eigenvector-trajectories T(s) for the for the clockwise (CW, [+1]) (red) and counter-clockwise (CCW, [−1]) (blue) circularly laser pulse polarized in yz plane 60 femtoseconds after the pulses are switched off. The end of each T(s) is denoted by a cube marker. The most (±e₂) and least (±e₁) preferred eigenvector directions of the total charge density accumulation ρ(r_b). The inset is the view down the ethane C1-C2 BCP bond-path, showing the Cartesian yz axes, where the BCPs are represented by undecorated green spheres.

Abstract

A pair of simulated left and right circularly polarized ultra-fast laser pulses of duration 20 femtoseconds that induce a mixture of excited states are applied to ethane. The response of the electron dynamics is investigated within the next generation quantum theory of atoms in molecules (NG-QTAIM) using third-generation eigenvector-trajectories which are introduced in this work. This enables an analysis of the mechanical and chiral properties of the electron dynamics of ethane without needing to subject the C-C bond to external torsions as was the case for second-generation eigenvector-trajectories. The mechanical properties, in particular, the bond-flexing and bond-torsion were found to increase depending on the plane of the applied laser pulses. The bond-flexing and bond-torsion, depending on the plane of polarization, increases or decreases after the laser pulses are switched off. This is explainable in terms of directionally-dependent effects of the long-lasting superpositions of excited states. The chiral properties correspond to the ethane molecule being classified as formally achiral consistent with previous NG-QTAIM investigations. Future planned investigations using ultra-fast circularly polarized lasers are briefly discussed.

Recent Advances in Base‐Metal‐Catalyzed Carbonylation of Unactivated Alkyl Electrophiles

Posted on 12 September 2023 by nWei Li, nDonghao Jiang, nCheng Wang, nLi‐Jie Chengn

This review summarizes the recent advances in base-metal-catalyzed carbonylative C—C, C—N, C—O, C—X coupling and other carbonylation reactions of unactivated alkyl electrophiles using CO as C1 source, providing efficient methods for the synthesis of diverse alkyl-substituted carbonyl compounds or their derivatives including ketones, amides, esters, acylsilanes, acylborons, acyl chlorides and alcohols.

Comprehensive Summary

Transition metal-catalyzed carbonylation reactions represent a direct and atom-economical approach to synthesize carbonyl compounds or their derivatives by using CO as a cheap and readily available C1 feedstock. While carbonylation of C(sp²)-hybridized electrophiles (e.g., aryl halides) is well developed, carbonylation of less reactive unactivated alkyl electrophiles remains challenging. Recently, the use of earth-abundant base metals including Cu, Co, Mn, Fe, Ni as catalysts has enabled advances in carbonylative coupling of alkyl electrophiles for approaching diverse carbonyl compounds or their derivatives, notably, some of which are of synthetic importance but difficult to be synthesized through previous reported methods. Herein, we have summarized and discussed these recent achievements in base-metal-catalyzed carbonylative C—C, C—N, C—O, C—X coupling and other carbonylation reactions of unactivated alkyl electrophiles using CO as C1 source.

Elastic and Conductive Cross‐linked Anion Exchange Membranes Based on Polyphenylene Oxide and Poly(vinyl alcohol) for H2‐O2 Fuel Cells

Posted on 12 September 2023 by

A series of cross-linked AEMs (c-DQPPO/PVA) are synthesized by using rigid polyphenylene oxide and flexible poly(vinyl alcohol) as the backbones. Dual cations are grafted on the PPO backbone to improve the ion exchange capacity (IEC), while glutaraldehyde is introduced to enhance compatibility and reduce swelling ratio of AEMs. In addition to the enhanced mechanical properties resulting from the rigid-flexible cross-linked network, c-DQPPO/PVA AEMs also exhibit impressive ionic conductivity, which can be attributed to their high IEC, good hydrophilicity of PVA, and well-defined micro-morphology. Additionally, due to confined dimension behavior and ordered micro-morphology, c-DQPPO/PVA AEMs demonstrate excellent chemical stability. Specifically, c-DQPPO/PVA-7.5 exhibits a wet-state tensile strength of 12.5 MPa and an elongation at break of 53.0% at 25 oC. Its OH− conductivity and swelling degree at 80 oC are measured to be 125.7 mS cm-1 and 8.2%, respectively, with an IEC of 3.05 mmol g-1. After 30 days in a 1 M NaOH solution at 80 oC, c-DQPPO/PVA-7.5 experiences degradation rates of 12.8% for tensile strength, 27.4% for elongation at break, 14.7% for IEC, and 19.2% for ion conductivity. With its excellent properties, c-DQPPO/PVA-7.5 exhibits a peak power density of 0.751 W cm-2 at 60 oC in an H2-O2 fuel cell.