Ligand-Dependent Intracluster Interactions in Electrochemical CO Reduction Using Cu Nanoclusters.

The electrochemical CO reduction reaction (CORR) has been extensively studied because it can be leveraged to directly convert CO into valuable hydrocarbons. Among the various catalysts, copper nanoclusters (Cu NCs) exhibit high selectivity and efficiency for producing CORR products owing to their unique geometric/electronic structures. However, the influence of protective ligands on the CORR performance of Cu NCs remains unclear.

Platinum-Catalyzed Diboration of Alkynes by 1,8-Diaminonaphthalene-Protected Diboronic Acid (B(dan)).

The diboration of alkynes by 1,8-diaminonaphthalene-protected diboronic acid (B(dan)) proceeded smoothly in the presence of a platinum catalyst, and 1,2-diborylalkenes were isolated in up to 94% yield. The use of an appropriate solvent and ligand was critical for the progress of the reaction. The derivatization of 1,2-diborylalkenes was briefly examined.

Mechanistic study on the reductive elimination of (aryl)(fluoroaryl)palladium complexes: a key step in regiospecific dehydrogenative cross-coupling.

Cross-dehydrogenative coupling (CDC) reactions have attracted attention as short-step synthetic methods for C-C bond formation. Recently, we have developed CDC reactions between naphthalene and fluorobenzene. Rather than exhibiting general regioselectivity, this reaction proceeds selectively at the β-position of naphthalene.

Synthesis and Isolation of a Homochiral Nanohoop Composed of a Tröger's Base and Hexaparaphenylene.

Invited for the cover of this issue are Yusuke Yoshigoe, Hirotaka Shimada, and Shinichi Saito at the Tokyo University of Science, and Takuya Takaki and Yoshitane Imai at Kindai University. The image depicts a witch with a racemic pair of our nanohoops, TB[6]CPPs, chanting words shown in the font of a magical world. Read the full text of the article at 10.

Synthesis and Isolation of a Homochiral Nanohoop Composed of a Tröger's Base and Hexaparaphenylene.

The synthesis of a new nanohoop containing a stereogenic Tröger's base skeleton tethered to a curved hexaparaphenylene ([6]CPP) is reported. The TB[6]CPP nanohoop possesses a stable C symmetrical structure, which promotes the allowed transition that gives rise to pale blue emission with a quantum yield of ~0.69, surpassing the value of the more symmetrical [8]CPP.

Synthesis of Interlocked and Non-Interlocked Deca(para-phenylene) Derivatives by Ni-mediated Biaryl Coupling.

Oligo(para-phenylene) (PPn) is a compound composed of directly connected 1,4-phenylene moieties. The synthesis of PPn composed of six or more phenylene moieties with no substituent at the internal phenylene moiety has been challenging because of its low solubility. Herein we synthesized oligo(para-phenylene)[2]rotaxanes, including a deca(para-phenylene)[2]rotaxane, with a defined number of phenylene moieties.

Copper-Catalyzed Borylation of Styrenes by 1,8-Diaminonaphthalene-Protected Diboronic Acid.

We report a concise synthesis of 1,8-diaminonaphthalene-protected diboronic acid (B(dan)), which is a promising borylating agent. B(dan) is a bench-stable compound, and it could be utilized for Cu-catalyzed borylation of styrene derivatives. The reaction proceeded in a highly selective manner, and the products were isolated in up to 97% yields.

Synthesis and stereochemistry of chiral aza-boraspirobifluorenes with tetrahedral boron-stereogenic centers.

We have synthesized chiral aza-boraspirobifluorenes and evaluated their structural and photophysical properties. Enantiomers were separated by chiral HPLC on a semi-preparative scale, and the absolute stereochemistry was determined by comparison of experimental circular dichroism (CD) spectra and theoretical electronic CD (ECD) spectra. A kinetic analysis combined with theoretical calculations revealed that the rate-determining step of the racemization involves the cleavage of the B-N bond.

Dynamic Au-C σ-Bonds Leading to an Efficient Synthesis of []Cycloparaphenylenes ( = 9-15) by Self-Assembly.

The transmetalation of the digold(I) complex [AuCl(dcpm)] () (dcpm = bis(dicyclohexylphosphino)methane) with oligophenylene diboronic acids gave the triangular macrocyclic complexes [Au(CH) (dcpm)] ( = 3, 4, 5) with yields of over 70%. On the other hand, when the other digold(I) complex [AuCl(dppm)] () (dppm = bis(diphenylphosphino)methane) was used, only a negligible amount of the triangular complex was obtained. The control experiments revealed that the dcpm ligand accelerated an intermolecular Au(I)-C σ-bond-exchange reaction and that this high reversibility is the origin of the selective formation of the triangular complexes.

Phenanthroline based rotaxanes: recent developments in syntheses and applications.

The advancements in the field of mechanically interlocked molecular systems (MIMs) has concurrently restructured the material chemistry frontiers and provided ample scope to explore new dimensions for applications and diversity creation. Among all these molecular entities, rotaxanes have a special locale and many research groups over the globe have contributed to their current niche in supramolecular chemistry. From refinements for better yielding synthetic strategies to their application oriented designs, this field has come a long way and is well inclined for further developments.

Conformational Control of [2]Rotaxane by Hydrogen Bond.

A series of [2]rotaxanes with various functional groups in the axle component was synthesized by the oxidative dimerization of alkynes, which is mediated by a macrocyclic phenanthroline-Cu complex. The rotaxanes were fully characterized by spectroscopic methods, and the structure of a rotaxane was determined by X-ray crystallographic analysis. The interaction between the ring component and the axle component was studied in detail to understand the conformation of the rotaxanes.

The Aza-Prins Reaction of 1,2-Dicarbonyl Compounds with 3-Vinyltetrahydroquinolines: Application to the Synthesis of Polycyclic Spirooxindole Derivatives.

The aza-Prins reaction of 6,7-dimethoxy-3-vinyl-1,2,3,4-tetrahydroquinoline () with 1,2-dicarbonyl compounds proceeded smoothly in the presence of HCl, and the corresponding tricyclic benzazocines were isolated in yields of 20-86%. The reaction proceeded in a stereoselective manner, and the formation of the 2,4- isomer was observed. The reaction of with an enantiopure ketoester gave the corresponding tricyclic benzazocine as a mixture of diastereomers.

Regioselective C-H Trifluoromethylation of Aromatic Compounds by Inclusion in Cyclodextrins.

A regioselective radical C-H trifluoromethylation of aromatic compounds was developed using cyclodextrins (CDs) as additives. The C-H trifluoromethylation proceeded with high regioselectivity to afford the product in good yield, even on the gram scale. In the presence of CDs, some substrates underwent a single trifluoromethylation selectively, whereas mixtures of single- and double-trifluoromethylated products were formed in the absence of the CD.

Synthesis, structures and photophysical properties of hexacoordinated organosilicon compounds with 2-(2-pyridyl)phenyl groups.

We synthesised novel hexacoordinated organosilicon compounds with two 2-(2-pyridyl)phenyl groups. Single-crystal X-ray structure analyses indicated that Lewis acid-base interactions exist between the silicon atom and two nitrogen atoms of the pyridine rings, and that hexacoordinated organosilicon compounds have slightly distorted octahedral structures in the solid state. The hexacoordinated organosilicon compounds are stable in air, water, heat, acids, and bases.

Lewis acid-catalyzed synthesis of silafluorene derivatives from biphenyls and dihydrosilanes via a double sila-Friedel-Crafts reaction.

The synthesis of silafluorene derivatives from aminobiphenyl compounds and dihydrosilanes via a double sila-Friedel-Crafts reaction using a borane catalyst has been achieved. This method is applicable to the synthesis of a variety of silafluorene derivatives, such as multisubstituted silafluorenes, spirosilabifluorenes, and silicon-bridged terphenyl compounds, which are not readily obtained using conventional synthetic methods. In addition, we have demonstrated the transformation of the amino groups in these silafluorene derivatives into other substituents.

Control of Multicolor and White Emission by Adjusting the Equilibrium between Fluorophores, Lewis Acids, and Their Complexes in Polymers.

Multicolor emissive materials consisting of a single luminophore, a Lewis acid, and their complex were developed. The emission colors can be tuned by changing the concentration of the solution and the ratio of mixed solvents. Various emission colors in the solid state were observed when the complexes were added to polymers in different amounts.

Iron-Catalyzed ortho-Selective C-H Borylation of 2-Phenylpyridines and Their Analogs.

Treatment of 2-phenylpyridines (or their analogs) with a 9-bicycloboranonane dimer (9-BBN dimer) in the presence of a catalytic amount of a commercially available iron salt, FeBr, gave ortho-borylated products in moderate to excellent yields with good functional group tolerance. The reaction proceeded in good yield, even in gram-scale, and also occurred at the C-H bond of heteroaromatic compounds. The cost of the C-H borylation is dramatically lower than that of a previously reported similar palladium-catalyzed reaction.

Helicity-selective photoreaction of single-walled carbon nanotubes with organosulfur compounds in the presence of oxygen.

This report describes a helicity-selective photoreaction of single-walled carbon nanotubes (SWNTs) with disulfide in the presence of oxygen. The SWNTs were characterized using absorption, photoluminescence (PL), Raman, and X-ray photoelectron spectroscopy, scanning electron microscopy, and current-voltage (I-V) measurements. Results showed remarkable helicity-selective (metallic SWNTs/semiconducting SWNTs and diameter) functionalization of SWNTs.