Doping of a hydride (H) into an oblate-shaped gold cluster [Au(PPh)] was observed for the first time by mass spectrometry and NMR spectroscopy. Density functional theory calculations for the product [AuH(PPh)] demonstrated that the (AuH) core can be viewed as a nearly spherical superatom with a closed electronic shell. The hydride-doped superatom (AuH) was successfully converted to the well-known superatom Au, providing a new atomically precise synthesis of Au clusters via a bottom-up approach.

The timing and characteristics of neuronal death in Alzheimer's disease (AD) remain largely unknown. Here we examine AD mouse models with an original marker, myristoylated alanine-rich C-kinase substrate phosphorylated at serine 46 (pSer46-MARCKS), and reveal an increase of neuronal necrosis during pre-symptomatic phase and a subsequent decrease during symptomatic phase. Postmortem brains of mild cognitive impairment (MCI) rather than symptomatic AD patients reveal a remarkable increase of necrosis. In vivo imaging reveals instability of endoplasmic reticulum (ER) in mouse AD models and genome-edited human AD iPS cell-derived neurons. The level of nuclear Yes-associated protein (YAP) is remarkably decreased in such neurons under AD pathology due to the sequestration into cytoplasmic amyloid beta (Aβ) aggregates, supporting the feature of YAP-dependent necrosis. Suppression of early-stage neuronal death by AAV-YAPdeltaC reduces the laterstage extracellular Aβ burden and cognitive impairment, suggesting that preclinical/prodromal YAP-dependent neuronal necrosis represents a target for AD therapeutics.

A hydride (H)-doped bimetallic superatom (HPdAu) was produced by reacting BH with an oblate (PdAu) superatom protected by PPh. The H atom in (HPdAu) survived during the sequential addition of Au(I)Cl to form an (HPdAu) superatom, in sharp contrast to the proton release from a H-doped pure gold superatom (HAu) in the growth process to (Au). Single-crystal X-ray diffraction analysis and density functional theory calculations on (HPdAu) showed that the interstitially doped H atom induced a notable deformation of the core.

The fluxional nature of small gold clusters has been exemplified by reversible isomerization between [Au(PPh)] with a crown motif (Au(C)) and that with a butterfly motif (Au(B)) induced by association and dissociation with compact counteranions (NO, Cl). However, structural isomerization was suppressed by substitution of the central Au atom of the Au core in [Au(PPh)] with a Pd atom: [PdAu(PPh)] with a crown motif (PdAu(C)) did not isomerize to that with a butterfly motif (PdAu(B)) upon association with the counteranions. Density functional theory calculation showed that the energy difference between PdAu(C) and PdAu(B) is comparable to that between Au(C) and Au(B), indicating that the relative stabilities of the isomers are not a direct cause for the suppression of isomerization. Temperature dependence of Debye-Waller factors obtained by X-ray absorption fine-structure analysis revealed that the intracluster bonds of PdAu(C) were stiffer than the corresponding bonds in Au(C). Natural bond orbital analysis suggested that the radial Pd-Au and lateral Au-Au bonds in PdAu(C) are stiffened due to the increase in the ionic nature and decrease in electrostatic repulsion between the surface Au atoms, respectively. We conclude that the formation of stiffer metal-metal bonds by Pd atom doping inhibits the isomerization from PdAu(C) to PdAu(B).

The conformation and electronic structure of dibenzo-24-crown-8 (DB24C8) complexes with K + ion were examined by ion mobility−mass spectrometry (IM−MS), ultraviolet (UV) photodissociation (UVPD) spectroscopy in the gas phase, and fluorescence spectroscopy in solution. Three structural isomers of DB24C8 (SymDB24C8, Asym1DB24C8, and Asym2DB24C8) in which the relative positions of the two benzene rings were different from each other were investigated. The IM−MS results at 86 K revealed a clear separation of two sets of conformers for the K + (SymDB24C8) and K + (Asym1DB24C8) complexes whereas the K + (Asym2DB24C8) complex revealed only one set. The two sets of conformers were attributed to the open and closed forms in which the benzene−benzene distances in the complexes were long (>6 Å) and short (<6 Å), respectively. IM−MS at 300 K could not separate the two conformer sets of the K + (SymDB24C8) complex because the interconversion between the open and closed conformations occurred at 300 K and not at 86 K. The crown cavity of DB24C8 was wrapped around the K + ion in the complex, although the IM−MS results availed direct evidence of rapid cavity deformation and the reconstruction of stable conformers at 300 K. The UVPD spectra of the K + (SymDB24C8) and K + (Asym1DB24C8) complexes at ∼10 K displayed broad features that were accompanied by a few sharp vibronic bands, which were attributable to the coexistence of multiple conformers. The fluorescence spectra obtained in a methanol solution suggested that the intramolecular excimer was formed only in K + (SymDB24C8) among the three complexes because only SymDB24C8 could possibly assume a parallel configuration between the two benzene rings upon K + encapsulation. The encapsulation methods for K + ion (the "wraparound" arrangement) are similar in the three structural isomers of DB24C8, although the difference in the relative positions of the two benzene rings affected the overall cross-section. This study demonstrated that temperature-controlled IM−MS coupled with the introduction of appropriate bulky groups, such as aromatic rings to host molecules, could reveal the dynamic aspects of encapsulation in host−guest systems.