Semiconductive Copper(I)–Organic Frameworks for Efficient Light‐Driven Hydrogen Generation Without Additional Photosensitizers and Cocatalysts

As the first example of a photocatalytic system for splitting water without additional cocatalysts and photosensitizers, the comparatively cost‐effective Cu₂I₂‐based MOF, Cu‐I‐bpy (bpy=4,4′‐bipyridine) exhibited highly efficient photocatalytic hydrogen production (7.09 mmol g⁻¹ h⁻¹). Density functional theory (DFT) calculations established the electronic structures of Cu‐I‐bpy with a narrow band gap of 2.05 eV, indicating its semiconductive behavior, which is consistent with the experimental value of 2.00 eV. The proposed mechanism demonstrates that Cu₂I₂ clusters of Cu‐I‐bpy serve as photoelectron generators to accelerate the copper(I) hydride interaction, providing redox reaction sites for hydrogen evolution. The highly stable cocatalyst‐free and self‐sensitized Cu‐I‐bpy provides new insights into the future design of cost‐effective d¹⁰‐based MOFs for highly efficient and long‐term solar fuels production.     

Quasi‐Dual‐Packed‐Kerneled Au49(2,4‐DMBT)27 Nanoclusters and the Influence of Kernel Packing on the Electrochemical Gap

Although face‐centered cubic (fcc), body‐centered cubic (bcc), hexagonal close‐packed (hcp), and other structured gold nanoclusters have been reported, it was unclear whether gold nanoclusters with mix‐packed (fcc and non‐fcc) kernels exist, and the correlation between kernel packing and the properties of gold nanoclusters is unknown. A Au₄₉(2,4‐DMBT)₂₇ nanocluster with a shell electron count of 22 has now been been synthesized and structurally resolved by single‐crystal X‐ray crystallography, which revealed that Au₄₉(2,4‐DMBT)₂₇ contains a unique Au₃₄ kernel consisting of one quasi‐fcc‐structured Au₂₁ and one non‐fcc‐structured Au₁₃ unit (where 2,4‐DMBTH=2,4‐dimethylbenzenethiol). Further experiments revealed that the kernel packing greatly influences the electrochemical gap (EG) and the fcc structure has a larger EG than the investigated non‐fcc structure.     

Full Protection of Intensely Luminescent Gold(I)–Silver(I) Cluster by Phosphine Ligands and Inorganic Anions

An intensely luminescent gold(I)–silver(I) cluster [(C)(AuPPhpy₂)₆Ag₆(CF₃CO₂)₃](BF₄)₅ (PPhpy₂=bis(2‐pyridyl)phenylphosphine) ( 3 ) is synthesized by the reaction of [(C)(AuPPhpy₂)₆Ag₄](BF₄)₆ with AgCF₃CO₂. All eight faces of the octahedral C@Au₆ core in 3 are capped, that is, six faces are capped by silver ions and two by tetrafluoroborates. Cluster 3 is intensely luminescent in solution with a quantum yield of 92 %. Ligation of CF₃CO₂⁻ ions is vital for the construction and emission properties of 3 , as confirmed by DFT calculations. BF₄⁻ ions are involved in the protecting sphere of the metal core, as evidenced by ¹⁹F NMR data. The participation of phosphines, CF₃CO₂⁻, and BF₄⁻ ions in the protection of the emissive core and the enhancement of the rigidity of the cluster result in the high emission efficiency. This is the first example of organic ligands and inorganic anions forming a rigid protecting sphere for luminescent coinage‐metal clusters.     

Synthesis of Chiral Vicinal Diamines by Silver(I)‐Catalyzed Enantioselective Aminolysis of N‐Tosylaziridines

The kinetic resolution of 2‐aryl‐N‐tosylaziridines and the asymmetric desymmetrization of meso ‐N‐tosylaziridines by ring openings with various primary and secondary anilines, and aliphatic amines as nucleophile have been realized by using a single silver(I)/chiral diphosphine complex as catalyst for the first time. The simple starting materials, broad scope, and easy scalability render this protocol a practical way to chiral vicinal diamine derivatives.     

Structural Diversity of Copper(I)–N‐Heterocyclic Carbene Complexes; Ligand Tuning Facilitates Isolation of the First Structurally Characterised Copper(I)–NHC Containing a Copper(I)–Alkene Interaction

The preparation of a series of imidazolium salts bearing N‐allyl substituents, and a range of substituents on the second nitrogen atom that have varying electronic and steric properties, is reported. The ligands have been coordinated to a copper(I) centre and the resulting copper(I)–NHC (NHC=N‐heterocyclic carbene) complexes have been thoroughly examined, both in solution and in the solid‐state. The solid‐state structures are highly diverse and exhibit a range of unusual geometries and cuprophilic interactions. The first structurally characterised copper(I)–NHC complex containing a copper(I)–alkene interaction is reported. An N‐pyridyl substituent, which forms a dative bond with the copper(I) centre, stabilises an interaction between the metal centre and the allyl substituent of a neighbouring ligand, to form a 1D coordination polymer. The stabilisation is attributed to the pyridyl substituent increasing the electron density at the copper(I) centre, and thus enhancing the metal(d)‐to‐alkene(π*) back‐bonding. In addition, components other than charge transfer appear to have a role in copper(I)–alkene stabilisation because further increases in the Lewis basicity of the ligand disfavours copper(I)–alkene binding.     

Trifluoroacetic Anhydride Promoted Copper(I)‐Catalyzed Interrupted Click Reaction: From 1,2,3‐Triazoles to 3‐Trifluoromethyl‐Substituted 1,2,4‐Triazinones

A copper(I)‐catalyzed interrupted click reaction in the presence of trifluoroacetic anhydride has been developed, wherein an N‐trifluoroacetyl group is used to accelerate the ring‐opening of the putative 5‐copper(I) triazolide intermediate. Under the optimized reaction conditions, a broad range of azides and alkynes were found to participate in this transformation, thus affording 3‐trifluoromethyl‐substituted 1,2,4‐triazinones in moderate to excellent yields. The reaction has proven to be compatible with a variety of electron‐withdrawing and electron–donating groups, halogens, and nitrogen‐ and sulfur‐containing heterocycles, as well as pharmaceutically relevant molecules.