Redox-Induced Modulation of Exchange Interaction in a High-Spin Ground-State Diradical/Triradical System

A triplet ground-state diradical molecule, bis(nitronyl nitroxide)-substituted diphenyldihydrophenazine ( 1 ^..), that can be converted into a one-electron oxidized species, 1 ^{… +} , in the quartet ground state has been developed. Surprisingly, these species, 1 ^.. and 1 ^{… +} , can be used under ambient conditions because they are reasonably stable under aerobic conditions, even in solution. The temperature-dependent magnetic susceptibilities reveal that 1 ^.. and 1 ^{… +} are in the triplet state, with a weak exchange interaction (J₁/k_B = +3.1 K) and quartet ground state with a strong exchange interaction (J₂/k_B = +160 K), respectively. The interconversion between the neutral and one-electron oxidized species can be realized through electrochemical reactions. Significantly different absorption bands in the near-IR region newly appeared in the electronic spectra acquired during electrochemical oxidation/reduction.     

A Structurally Robust Chiral Borate Ion: Molecular Design,Synthesis, and Asymmetric Catalysis

Catalysis by chiral weakly‐coordinating anions (WCAs) remains underdeveloped due to the lack of a molecular design strategy for exploiting their characteristics, such as the non‐nucleophilic nature. Here, we report the development of a chiral borate ion comprising an O,N,N,O‐tetradentate backbone, which ensures hitherto unattainable structural robustness. Upon pairing with a proton, the hydrogen borate acts as an effective catalyst for the asymmetric Prins‐type cyclization of vinyl ethers, providing access to structurally and stereochemically defined dihydropyrans. The key to selectivity control is the distinct ability of the borate ion to discriminate the prochiral faces of the acyclic oxonium ion intermediate and dictate the regiochemical outcome. We anticipate that this study paves the way for exploring the untapped potential of WCA catalysis for selective chemical synthesis.     

Synthesis of Porphyrinquinone and Doubly‐Fused Diporphyrin Quinone Through Oxidation of Diarylporphyrins Using a Hypervalent Iodine Compound

Treatment of a meso‐diarylporphyrin with PhI(OAc)₂ in the presence of BF₃ ? OEt₂ and propionic acid affords the corresponding porphyrinquinone in a high yield (91%). A novel quinone derived from meso‐meso β–β doubly‐fused diporphyrin was obtained as the sole byproduct (16% yield), which exhibits strong panchromatic absorption between 300 and 1000 nm. It has a low HOMO‐LUMO gap owing to expanded and low‐symmetry π‐planes.     

The axiom of real Blackwell determinacy

The theory of infinite games with slightly imperfect information has been developed for games with finitely and countably many moves. In this paper, we shift the discussion to games with uncountably many possible moves, introducing the axiom of real Blackwell determinacy ${\mathsf{Bl-AD}_\mathbb{R}}$ (as an analogue of the axiom of real determinacy ${\mathsf{AD}_\mathbb{R}}$ ). We prove that the consistency strength of ${\mathsf{Bl-AD}_\mathbb{R}}$ is strictly greater than that of AD.     

Nonarchimedean Green functions and dynamics on projective space

Let \({\varphi: \mathbb{P}^N_K\to\mathbb{P}^N_K}\) be a morphism of degree d ≥ 2 defined over a field K that is algebraically closed field and complete with respect to a nonarchimedean absolute value. We prove that a modified Green function \({\hat{g}_\varphi}\) associated to \({\varphi}\) is Hölder continuous on \({\mathbb{P}^N(K)}\) and that the Fatou set \({\mathcal{F}(\varphi)}\) of \({\varphi}\) is equal to the set of points at which \({\hat{g}_\Phi}\) is locally constant. Further, \({\hat{g}_\varphi}\) vanishes precisely on the set of points P such that \({\varphi}\) has good reduction at every point in the forward orbit \({\mathcal{O}_\varphi(P)}\) of P. We also prove that the iterates of \({\varphi}\) are locally uniformly Lipschitz on \({\mathcal{F}(\varphi)}\) .     

Influence of Cu electroplating solutions on boron carbon nitride (BCN) film

Cu electroplating is required for the fabrication of Cu/low-k interconnections. The permeation of a plating solution into low-k films during Cu electroplating is a serious challenge for 45-nm nodes and more complex devices. We investigated the influence of Cu electroplating solutions on boron carbon nitride (BCN) as a low-k film. After dipping it into a Cu electroplating solution that contained additives, the BCN film's hydrophilic surface changed to a hydrophobic surface, and the incorporation of water into the BCN film was suppressed by surfactant adsorption. Sulfuric residue was detected on the BCN sample by thermal desorption spectroscopy after treatment in the Cu electroplating solution with additives; however, it was found through electrical measurements that this solution did not affect the leakage current or the dielectric constant of the BCN film. We successfully fabricated an electroplating Cu layer on a BCN film with good adhesion, and we believe that this BCN film is a sufficiently useful material for Cu/BCN integration in LSI.     

On a conjecture of ōshima

The set of homotopy classes of self maps of a compact, connected Lie group G is a group by the pointwise multiplication which we denote by H(G), and it is known to be nilpotent. ōshima [H. ōshima, Self homotopy group of the exceptional Lie group G₂, J. Math. Kyoto Univ. 40 (1) (2000) 177-184] conjectured: if G is simple, then H(G) is nilpotent of class ?rankG. We show this is true for PU(p) which is the first high rank example.     

A CO Adsorption Site Change Induced by Copper Substitution in a Ruthenium Catalyst for Enhanced CO Oxidation Activity

Ru is an important catalyst in many types of reactions. Specifically, Ru is well known as the best monometallic catalyst for oxidation of carbon monoxide (CO) and has been practically used in residential fuel cell systems. However, Ru is a minor metal, and the supply risk often causes violent fluctuations in the price of Ru. Performance‐improved and cost‐reduced solid‐solution alloy nanoparticles of the Cu‐Ru system for CO oxidation are now presented. Over the whole composition range, all of the Cu_xRu_1?x nanoparticles exhibit significantly enhanced CO oxidation activities, even at 70 at % of inexpensive Cu, compared to Ru nanoparticles. Only 5 at % replacement of Ru with Cu provided much better CO oxidation activity, and the maximum activity was achieved by 20 at % replacement of Ru by Cu. The origin of the high catalytic performance was found as CO site change by Cu substitution, which was investigated using in situ Fourier transform infrared spectra and theoretical calculations.     

Rational Design and Identification of a Non‐Peptidic Aggregation Inhibitor of Amyloid‐β Based on a Pharmacophore Motif Obtained from cyclo[‐Lys‐Leu‐Val‐Phe‐Phe‐]

Inhibition of pathogenic protein aggregation may be an important and straightforward therapeutic strategy for curing amyloid diseases. Small‐molecule aggregation inhibitors of Alzheimer’s amyloid‐β (Aβ) are extremely scarce, however, and are mainly restricted to dye‐ and polyphenol‐type compounds that lack drug‐likeness. Based on the structure‐activity relationship of cyclic Aβ16–20 (cyclo‐[KLVFF]), we identified unique pharmacophore motifs comprising side‐chains of Leu², Val³, Phe⁴, and Phe⁵ residues without involvement of the backbone amide bonds to inhibit Aβ aggregation. This finding allowed us to design non‐peptidic, small‐molecule aggregation inhibitors that possess potent activity. These molecules are the first successful non‐peptidic, small‐molecule aggregation inhibitors of amyloids based on rational molecular design.