Capacitance enhancement by ion-laminated borophene-like layered materials.

Atomically flat two-dimensional networks of boron are attracting attention as post-graphene materials. An introduction of cations between the boron atomic layers can exhibit unique electronic functions that are not achieved by neutral graphene or its derivatives. In the present study, we propose a synthesis strategy for ion-laminated boron layered materials in a solution phase, which enables the preparation of analogs by changing the alkali-metal species.

Development of a Ru-porphyrin-based supramolecular framework catalyst for styrene epoxidation.

A new microporous supramolecular-framework Ru(II)-porphyrin catalyst containing non-covalent interactions between pyrenylphenyl moieties at the -position of the porphyrin ring is synthesised and structurally characterised. This recyclable catalyst expedites styrene epoxidation more efficiently than homogeneous Ru-porphyrin catalytic systems.

Photoinduced Self-assembly: An Alternative Strategy for the Construction of Coordination Oligomers and Polymers.

Self-assembled oligonuclear and polynuclear complexes have numerous functionalities and potential applications. Generally, such compounds have been constructed by thermal substitution reactions with bridging ligands. Herein, we report bottom-up and photochemical construction of functional coordination oligomers and polymers by photosubstitution-induced self-assembly.

Photocatalytic Three-Component Acylcarboxylation of Alkenes with CO.

γ-Keto acid is a valuable chemical motif in a wide range of fields including organic, biological, and medicinal chemistry. However, its single-step synthesis is challenging because of the mismatch of the carbonyl polarity and low tolerance of carboxylic acids. Herein, we report the single-step syntheses of γ-keto acids using alkenes and CO.

Precise Manipulation of Electron Transfers in Clustered Five Redox Sites.

Electron transfers in multinuclear metal complexes are the origin of their unique functionalities both in natural and artificial systems. However, electron transfers in multinuclear metal complexes are generally complicated, and predicting and controlling these electron transfers is extremely difficult. Herein, we report the precise manipulation of the electron transfers in multinuclear metal complexes.

Reticular Imine-Linked Coordination Polymers Based on Paddlewheel Diruthenium/Dirhodium Nodes: Synthesis and Metal-Site Dependent Photocatalytic Reduction of CO.

The paddlewheel-type dimetal core ([M]) is a ubiquitous motif in the nodes in coordination polymers (CPs) and metal-organic frameworks (MOFs). However, their preparation has relied on ligand-substitution-labile metal ions owing to challenges associated with crystallization. Consequently, examples featuring ligand-substitution-inert metal ions, such as Ru or Rh, are scarce.

Introducing proton/electron mediators enhances the catalytic ability of an iron porphyrin complex for photochemical CO reduction.

A novel iron porphyrin complex with hydroquinone moieties as proton/electron mediators at positions was designed and synthesised. The complex serves as an efficient catalyst for photochemical CO reduction, and its turnover frequency (TOF = 1.3 × 10 h) was the highest among those of comparable systems with sufficient durability.

Iron-Complex-Based Supramolecular Framework Catalyst for Visible-Light-Driven CO Reduction.

Molecule-based heterogeneous photocatalysts without noble metals are one of the most attractive systems for visible-light-driven CO reduction. However, reports on this class of photocatalysts are still limited, and their activities are quite low compared to those containing noble metals. Herein, we report an iron-complex-based heterogeneous photocatalyst for CO reduction with high activity.

Visible-Light-Driven Hydroacylation of Unactivated Alkenes Using Readily Available Acyl Donors.

Herein, we report visible-light-driven hydroacylation of unactivated alkenes. We employed benzimidazolines as new acyl donors and achieved perfect regioselectivity, high functional-group tolerance, and excellent substrate generality. We also performed mechanistic experiments to elucidate the detailed reaction mechanism.

Brønsted Acid/Base Site Isolated in a Pentanuclear Scaffold.

Invited for the cover of this issue is the group of Shigeyuki Masaoka at Osaka University. The image depicts a Brønsted acid/base pair based on a pentanuclear scaffold, and the formation thermodynamically metastable state of H by the steric isolation of a Brønsted acid/base site. Read the full text of the article at 10.

Brønsted Acid/Base Site Isolated in a Pentanuclear Scaffold.

The concept of Brønsted-Lowry acids and bases is long and widely recognized as the most reasonable theory to explain the behavior of H ions. Here, we report a Brønsted acid/base pair that does not follow this theory. Two heteronuclear metal complexes, in which Brønsted acid/base sites are sterically isolated, were synthesized and characterized.

A Catalytic Alkylation of Ketones via C-H Bond Activation.

We identified a ternary hybrid catalyst system composed of an acridinium photoredox catalyst, a thiophosphoric imide (TPI) catalyst, and a titanium complex catalyst that promoted an intermolecular addition reaction of organic molecules with various ketones through sp C-H bond activation. The thiyl radical generated via single-electron oxidation of TPI by the excited photoredox catalyst abstracted a hydrogen atom from organic molecules such as toluene, benzyl alcohol, alkenes, aldehydes, and THF. The thus-generated carbon-centered radical species underwent addition to ketones and aldehydes.

Visible light-driven CO reduction with a Ru polypyridyl complex bearing an N-heterocyclic carbene moiety.

A novel Ru polypyridyl complex with an N-heterocyclic carbene ligand was successfully synthesised and characterised. The complex exhibited an intense absorption band in the visible-light region derived from the strong electron-donating character of the carbene ligand, and efficiently catalysed the visible light-driven CO reduction with the reaction rate of 36.7 h.

Photochemical hydrogen production based on the HCOOH/CO cycle promoted by a pentanuclear cobalt complex.

The first catalytic cycle for hydrogen production based on the photochemical two-electron reduction of carbon dioxide (CO) and the dehydrogenation of formic acid at ambient temperature was demonstrated using a pentanuclear cobalt complex (Co5). A series of mechanistic studies were performed to elucidate the mechanism responsible for the promotion of the photocatalytic cycle by Co5.

Copper(II) tetrakis(pentafluorophenyl)porphyrin: highly active copper-based molecular catalysts for electrochemical CO reduction.

We report a highly active copper-based catalyst for electrochemical CO reduction. Electrochemical analysis revealed that the maximum turnover frequency for CO to CO conversion reached 1 460 000 s at an overpotential () of 0.85 V.

Bridging coordination of acenaphthylene to a Pd chain or a Pd sheet cluster.

The coordination behaviour of multinuclear clusters to fused arene ligands is of continuous interest due to its relevance to metal catalysts supported by graphitic carbon materials. Herein, we report the bridging coordination behaviour of acenaphthylene to a Pd or a Pd cluster. A bis-acenaphthylene Pd chain cluster and an acenaphthylene-COT Pd sheet cluster were isolated, and the μ-π-coordination mode or the μ-oxidative π-addition mode of the acenaphthylene ligand in each cluster was elucidated by X-ray structure analysis.

Quick and Easy Method to Dramatically Improve the Electrochemical CO Reduction Activity of an Iron Porphyrin Complex.

The development of artificial molecular catalysts for CO reduction is the key to solving energy and environmental problems. Although chemical modifications can generally improve the catalytic activity of this class of compounds, they often require complicated synthetic procedures. Here, we report a simple procedure that dramatically enhances electrochemical CO reduction activity.

Dirhodium-Based Supramolecular Framework Catalyst for Visible-Light-Driven Hydrogen Evolution.

The direct conversion of solar energy to clean fuels as alternatives to fossil fuels is an important approach for addressing the global energy shortage and environmental problems. Here, we introduce a new dirhodium-complex-based framework assembly as a heterogeneous molecule-based photocatalyst for hydrogen evolution using visible light. Two dirhodium complexes bearing visible-light-harvesting BODIPY (boron dipyrromethene, BDP) moieties were newly designed and synthesized.

Photocatalytic redox-neutral hydroxyalkylation of -heteroaromatics with aldehydes.

Hydroxyalkylation of -heteroaromatics with aldehydes was achieved using a binary hybrid catalyst system comprising an acridinium photoredox catalyst and a thiophosphoric acid organocatalyst. The reaction proceeded through the following sequence: (1) photoredox-catalyzed single-electron oxidation of a thiophosphoric acid catalyst to generate a thiyl radical, (2) cleavage of the formyl C-H bond of the aldehyde substrates by a thiyl radical acting as a hydrogen atom transfer catalyst to generate acyl radicals, (3) Minisci-type addition of the resulting acyl radicals to -heteroaromatics, and (4) a spin-center shift, photoredox-catalyzed single-electron reduction, and protonation to produce secondary alcohol products. This metal-free hybrid catalysis proceeded under mild conditions for a wide range of substrates, including isoquinolines, quinolines, and pyridines as -heteroaromatics, as well as both aromatic and aliphatic aldehydes, and tolerated various functional groups.

Design of molecular water oxidation catalysts with earth-abundant metal ions.

The four-electron oxidation of water (2H2O → O2 + 4H+ + 4e-) is considered the main bottleneck in artificial photosynthesis. In nature, this reaction is catalysed by a Mn4CaO5 cluster embedded in the oxygen-evolving complex of photosystem II. Ruthenium-based complexes have been successful artificial molecular catalysts for mimicking this reaction.

Photoconductive Coordination Polymer with a Lead-Sulfur Two-Dimensional Coordination Sheet Structure.

Coordination polymers with metal-sulfur (M-S) bonds in their nodes have interesting optical properties and can be used as photocatalysts for water splitting. A wide range of inorganic-organic hybrid materials with M-S bonds have been prepared in recent years. However, there is a dearth of structural information because of their low crystallinity, which has hampered the understanding of their underlying chemistry and physics.

Modulation of Self-Assembly Enhances the Catalytic Activity of Iron Porphyrin for CO Reduction.

Electrochemical reduction of CO in aqueous media is an important reaction to produce value-added carbon products in an environmentally and economically friendly manner. Various molecule-based catalytic systems for the reaction have been reported thus far. The key features of state-of-the-art catalytic systems in this field can be summarized as follows: 1) an iron-porphyrin-based scaffold as a catalytic center, 2) a dinuclear active center for the efficient activation of a CO molecule, and 3) a hydrophobic channel for the accumulation of CO .