Yukatsu Shichibu

A pyridyl-diphosphine scaffold directs the regiospecific anchoring of M ₂ dimers onto a Au6 cluster. This coordination-driven alloying triggers a structural rearrangement and boosts NIR emission by up to 150-fold.

Evolution of the Au ₁₃ cluster size and the increase in the fraction of nanoparticles enhance the H ₂ O ₂ yield and production rate due to the formation of a metal–support interaction and larger Au particles.

Atomically-precise ligand-protected gold clusters have garnered wide attention as a catalytic active site in photocatalysis. Using the [Au13(dppe)5Cl2]Cl3 cluster (Au13 for convenience) deposited onto WO3, we investigated the effects of calcination temperature on the photocatalyst performance for H2O2 production. Heat treatments at different temperatures (160, 180 and 200 ºC) in air causes a gradual increase in Au size from 0.93 nm to 2.86 nm as verified using STEM imaging. Calcination at 160 °C still retains a majority of unaggregated clusters, while at 180 °C, both unaggregated clusters and aggregated particles are found in equal fraction (50:50), and at 200 °C a complete aggregation into larger Au particles occurs. The Au13/WO3-based photocatalysts only exhibit photoactivity in H2O2 production after calcination; WO3 and as-deposited Au13/WO3 are photocatalytically inactive. Transient photocurrent responses reveal that WO3 and Au13/WO3 exhibit the lowest photocurrent while calcined Au13/WO3 photocatalysts in the range of 160–200 °C show a dramatic enhancement in photocurrent indicating higher charge separation and transfer. The high activity of calcined Au13/WO3 is attributed to the existence of strong metal-support interaction that promotes charge separation and transfer, and formation of larger Au particles. Both rate constants of H2O2 formation (kf) and decomposition (kd) increase as the calcination temperature increases. The Au13/WO3 calcined at 200 °C displays the highest H2O2 production yield (2.1 mM) and rate (21 mM g-1 h-1) with apparent quantum yield of 1.27% under violet (405 nm) light irradiation. This work unravels the effects of calcination temperature on the photoactivity of Au13/WO3 photocatalyst for H2O2 synthesis.

Ligand-shell engineering of ultrasmall metal clusters is a burgeoning research field aiming to develop cluster-specific properties. However, predicting these properties prior to synthesis is challenging due to their high sensitivity to geometric and/or electronic variations in ultrasmall metal cores, hindering further exploration. In this study, we present a theory-directed ligand-shell design and significant red-shift in absorption of a prolate-shaped [Au₈(diphosphine)₄Cl₂]²⁺ cluster by synthesizing and characterizing enantiopure octagold clusters bearing chiral BINAP-type ligands [BINAP = 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl]. Crystallographic analysis reveals the predesigned ligand arrangement and twisted gold-core framework. The enantiomeric clusters show significant changes in both absorption and photoluminescence compared with a previous Au₈ analogue and exhibit chiroptical signals. Furthermore, theoretical calculations visually unveil the atomic level origins of their optical and chiroptical absorption characteristics. This work not only highlights the effectiveness of ligand-shell engineering in creating unique photophysical properties but also offers a viable, theory-guided strategy for designing and functionalizing ligated metal clusters.

2,9-Bis((1R,2S,5R)-2-isopropyl-5-methylcyclohexanoxy)-1,10-phenanthroline [2,9-di-L-menthoxy-1,10-phenanthroline] (Men2Phen) and 2,9-bis(2-(S)-methylbutoxy)-1,10-phenanthroline (MB2Phen) were synthesized as chiral derivatives of 1,10-phenanthroline (Phen). Differences in rigidity and bulkiness of the chiral substituents at the 2- and 9-positions of the Phen backbone led to distinctive molecular dissymmetry in the ground state resulting in remarkable differences in circular dichroism. Men2Phen exhibited efficient circularly polarized luminescence (CPLm) at an anisotropy factor of 10⁻² in the solid state based on molecular ordering disclosed by X-ray crystal analysis, while it showed much lower anisotropy factor in solution. MB2Phen, which was rather amorphous and did not afford good crystals, showed only negligible CPLm both in the solid state and in solution.

Sphere-shaped amorphous aggregates of Au₈ clusters entrapped within SDS nanoenvelopes are transformed into rhombic single nanocrystals upon simple sonication in solution, where the aggregation-induced emission (AIE) from Au₈ is notably enhanced.

A series of new gold nanocomposite materials, GNC_LCx (x = 6–11) derived from the non-linear liquid crystal oligomers, LCx (x = 6–11) and a gold nanocluster (GNC) possessing a formulation of [Au₂₅(SC₁₂H₂₅)₁₈]TOA or Au₂₅.

Perfluorination brings about distinctive properties arising from the unusual nature of the F element, which have been extensively developed in materials science and chemistry. Herein we report that the construction of F‐rich inner space within a hollowed Mo₁₃₂O₃₇₂ cage ([Mo₁₃₂O₃₇₂(OCOR)₃₀(H₂O)₇₂]⁴²⁻) leads to the emergence of unique guest binding activities in encapsulation. Prominently, the trifluoroacetate‐modified cage (R=CF₃, 2) having as many as 90 F groups inside favors trapping cyclopentadiene (Cp), which is hardly trapped by the non‐fluorinated counterpart (R=CH₃, 1). Systematic studies using related hydrocarbons show that the amount of the encapsulated guest is correlated with the unsaturation degree of the guests, implying the involvement of the attractive interaction of the CF₃‐modified interior wall with the guest π‐electron clouds. Control experiments using the semi‐fluorinated analogues (R=CF₂H, CFH₂) reveal that the perfluorination is a critical factor to facilitate the Cp encapsulation by 2, indicating that collective effects of polar C−F bonds spreading over the interior surface, rather than the polarity of the individual C−F bonds, are responsible. We also provide a successful example of the physical molecular confinement within the cage through the “ship‐in‐a‐bottle” Diels‐Alder reaction between trapped diene and dienophile.

Chiroptical activities of Au ₁₃ superatom modified with chiral ligands were enhanced by doping of an Ir atom at the center of the core. The IrAu ₁₂ superatom exhibited the brighter circularly polarized luminescence than Au ₁₃ superatom.