Publications by authors named "Ehara M"

Multijunction photovoltaics (PVs) are gaining prominence owing to their superior capability of achieving power conversion efficiencies (PCEs) beyond the radiative limit of single-junction cells, where improving narrow bandgap tin-lead perovskites is critical for thin-film devices. With a focus on understanding the chemistry of tin-lead perovskite precursor solutions, we herein find that Sn(II) species dominate interactions with precursors and additives and uncover the exclusive role of carboxylic acid in regulating solution colloidal properties and film crystallisation, and ammonium in improving film optoelectronic properties. Materials that combine these two function groups, amino acid salts, considerably improve the semiconducting quality and homogeneity of perovskite films, surpassing the effect of the individual functional groups when introduced as part of separate molecules.

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Circularly polarized luminescence (CPL) activity was induced on a racemic Tb complex with a 1,4,7-triazacyclononane-based tris-phenoxide ligand by the coordination of a chiral 1-phenylethylamine ligand to the Tb centre. -Butyl groups at the -position of the phenoxide moieties were found to be important for efficient CPL induction in the Tb complex.

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Article Synopsis
  • The article discusses the importance of cooperative interactions between metal nanoparticles and their supports in enhancing intermolecular bond formation, specifically in cross-coupling reactions.
  • Kinetic and theoretical studies on supported gold catalysts reveal that the Lewis acid density of supports influences the number of active sites for these reactions, highlighting the role of metal-support cooperation.
  • Optimized supported Au catalysts, particularly the Au/α-FeO variant, demonstrate exceptional efficiency in C-O bond borylation and also facilitate direct C-N bond borylation, showcasing the potential benefits of improving metal-metal oxide interactions in catalysis.
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Chemical etching of nano-sized metal clusters at the atomic level has a high potential for creating metal number-specific structures and functions that are difficult to achieve with bottom-up synthesis methods. In particular, precisely etching metal atoms one by one from nonmetallic element-centred metal clusters and elucidating the relationship between their well-defined structures, and chemical and physical properties will facilitate future materials design for metal clusters. Here we report the single-gold etching at a hypercarbon centre in gold(I) clusters.

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A 'passivated precursor' approach is developed for the efficient synthesis and isolation of all-alkynyl-protected gold nanoclusters. Direct reduction of dpa-passivated precursor Au-dpa (Hdpa=2,2'-dipyridylamine) in one-pot under ambient conditions gives a series of clusters including Au(C≡CR) (R=-CH-2-F), Au(C≡CR), Au(C≡CR), Au(C≡CR), and Au(C≡CR). These clusters can be well separated via column chromatography.

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Article Synopsis
  • Researchers studied how certain materials called photocatalysts, like niobium oxide (NbO), work to convert alcohol using light.
  • They found that different steps in this process happen when the alcohol sticks to the material and when it's exposed to UV or visible light, which affects how the alcohol changes.
  • The study helps scientists understand more about how these photocatalysts work, which could lead to better designs for future materials.
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Reinforcement learning (RL) has been applied to various domains in computational chemistry and has found wide-spread success. In this review, we first motivate the application of RL to chemistry and list some broad application domains, for example, molecule generation, geometry optimization, and retrosynthetic pathway search. We set up some of the formalism associated with reinforcement learning that should help the reader translate their chemistry problems into a form where RL can be used to solve them.

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Dynamic / invertible helicity was successfully induced at a SiO surface immobilized with a dynamic helical trinuclear cobalt complex, [LCo(NHMe)](OTf), using chiral (() or ())-1-phenylethylamine. Solid-state CD spectra and theoretical calculations suggested that the fixation of the / helical complex on the surface coordination interactions was the key factor of the induced chirality at the surface.

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Metal or metal cluster-doped zeolites catalyse a wide variety of reactions. In this work, a coupling reaction between bromobenzene and phenylboronic acid to yield biphenyl with the Pd-H-Beta zeolite catalyst was investigated with density functional theory (DFT) calculations. Utilizing a model system with tetrahedral Pd clusters within the H-Beta zeolite, it was demonstrated that the catalyst exhibited notable reactivity by effectively reducing the activation energy barrier for the reaction.

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Endohedral metal-metal-bonding fullerenes have recently emerged, in which encapsulated metals form a metal-metal bond. However, the physical reasons why some metal elements prefer to form metal-metal bonds inside fullerene are still unclear. Herein, we reported first-principles calculations on electronic structures, bonding properties, dynamics, and thermodynamic stabilities of endohedral metallofullerenes M2@C82 (M = Sc, Y, La, Lu).

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Molecular twist is a characteristic component of molecular machines. Selectively synthesising isomers with different modes of twisting and controlling their motion such as helicity inversion is an essential challenge for achieving more advanced molecular systems. Here we report a strategy to control the inversion kinetics: the kinetically selective synthesis of tightly- and loosely-twisted isomers of a trinuclear Pd-macrocycle and their markedly different molecular behaviours.

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The functionalization of single-walled carbon nanotubes (SWCNTs) has received considerable attention in the last decade since highly efficient near-infrared photoluminescence (PL) has been observed to be red-shifted compared with the intrinsic PL peak of pristine SWCNTs. The PL wavelength has been manipulated using arylation reactions with aryldiazonium salts and aryl halides. Additionally, simple oxidation and alkylation reactions have proven effective in extensively adjusting the PL wavelength, with the resulting PL efficiency varying based on the chosen reaction techniques and molecular structures.

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The challenge of achieving regioselective multifunctionalization on highly symmetric C and C fullerenes persists as a significant hurdle. In this study, we present a novel approach involving the participation of an oriented external electric field (OEEF) to facilitate the regioselective formation of bisadducts in C/C fullerenes. These products are obtained through consecutive Diels-Alder cycloaddition reactions.

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We report that the chirality inversion kinetics of a trinickel(II) cryptand can be controlled by guest recognition in the cryptand cavity. When the guest was absent, the nickel(II) cryptand underwent a dynamic interconversion between the and forms in solution, preferring the form, with a half-life of = 4.99 min.

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Electronic structures of anion-templated silver nanoclusters (Ag NCs) are not well understood compared to conventional, template-free Ag NCs. In this study, we synthesized three new anion-templated Ag NCs, namely [S@Ag(S-4CBM)(PPh)], [S@Ag(S-4CBM)(PPh)], and [Cl@Ag(S-4CBM)(PPh)][PPh], where S-4CBM = 4-chlorobenzene methanethiolate, and single-crystal X-ray crystallography revealed that they have S@Ag, S@Ag, and Cl@Ag cores, respectively. Investigation of their electronic structures by optical spectroscopy and theoretical calculations elucidated the following unique features: (1) their electronic structures are different from those of template-free Ag NCs described by the superatomic concept; (2) optical absorption in the range of 550-400 nm for S-templated Ag NCs is attributed to the charge transitions from S-templated Ag-cage orbitals to the s-shaped orbital in the S moiety; (3) the Cl-templated Ag NCs can be viewed as [Cl@Ag(S-4CBM)(PPh)][PPh] rather than the ion pair [Cl@Ag(S-4CBM)(PPh)][PPh]; and (4) singlet-coupled singly occupied orbitals are involved in the optical absorption of the Cl-templated Ag NC.

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Metal clusters have become increasingly important in various applications, with ligands playing a crucial role in their construction. In this study, we synthesized a bimetallic cluster, Ag Cu (C=CAr) (DPPB) (Ag Cu ), using a rigid acetylene ligand, 3,5-bis(trifluoromethyl)phenylacetylide. Through single-crystal structure characterization, we discovered that the butterfly-shaped Ag Cu motifs were subject to distortion due to steric hindrance imposed by the rigid ligand.

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Asbestos is the main cause of malignant mesothelioma. Previous studies have linked asbestos-induced mesothelioma to the release of HMGB1 from the nucleus to the cytoplasm, and from the cytoplasm to the extracellular space. In the cytoplasm, HMGB1 induces autophagy impairing asbestos-induced cell death.

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We conducted the chiral separation of functionalized single-walled carbon nanotubes (SWNTs) with dibromopropane derivatives. Depending on their chirality and diameter, the thermal treatment of functionalized SWNTs leads to a shift in the emission radiation to longer wavelengths owing to rearrangement reaction in competition with elimination reaction.

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Chemical functionalisation of semiconducting single-walled carbon nanotubes (SWNTs) can tune their local band gaps to induce near-infrared (NIR) photoluminescence (PL). However, tuning the PL to telecommunication wavelengths (>1300 nm) remains challenging. The selective emergence of NIR PL at the longest emission wavelength of 1320 nm was successfully achieved in (6,5) SWNTs via cyclic perfluoroalkylation.

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The properties of metal clusters are highly dependent on their molecular surface structure. The aim of this study is to precisely metallize and rationally control the photoluminescence properties of a carbon(C)-centered hexagold(i) cluster (CAu) using N-heterocyclic carbene (NHC) ligands with one pyridyl, or one or two picolyl pendants and a specific number of silver(i) ions at the cluster surface. The results suggest that the photoluminescence of the clusters depends highly on both the rigidity and coverage of the surface structure.

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Article Synopsis
  • The study investigates how nitrogen monoxide (NO) is activated on various metal/oxide interfaces using different metal cluster supports and density functional theory calculations.
  • The findings reveal that platinum (Pt) and rhodium (Rh) clusters have stronger adhesion to these surfaces compared to palladium (Pd), while the γ-AlO(100) surface has weaker adhesion overall.
  • The research highlights that, except for the SrFeO case, the process of NO activation is mostly exothermic, showcasing the important interaction between the metal cluster and oxygen vacancies during the reaction.
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The functionalization of single-walled carbon nanotubes (SWNTs) is an effective method for controlling a local band gap, resulting in photoluminescence (PL) in the near-infrared region. Herein, SWNTs were functionalized using a series of bromoalkanes and dibromoalkanes to evaluate the effects of their length on the nanotube PL properties. When bromoalkanes (C H Br) or dibromoalkanes (C H Br ) with tether lengths of six or more were utilized for six different semiconducting SWNTs, the obtained SWNT adducts exhibited two new PL peaks, whereas dibromoalkanes with tether lengths of 3-5 (C H Br : n=3-5) produced single peaks.

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Interfaces in thin-film photovoltaics play a pivotal role in determining device efficiency and longevity. In this work, the top surface treatment of mixed tin-lead (≈1.26 eV) halide perovskite films for p-i-n solar cells is studied.

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Endohedral metal-metal-bonding fullerenes, in which encapsulated metals form covalent metal-metal bonds inside, are an emerging class of endohedral metallofullerenes. Herein, we reported quantum-chemical studies on the electronic structures, chemical bonding, and dynamic fluxionality behavior of endohedral metal-metal-bonding fullerenes Lu@C (2n = 76-88). Multiple bonding analysis approaches, including molecular orbital analysis, the natural bond orbital analysis, electron localization function, adaptive natural density partitioning analysis, and quantum theory of atoms in molecules, have unambiguously revealed one two-center two-electron σ covalent bond between two Lu ions in fullerenes.

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Molecules close to a metal nanoparticle (NP) have significantly different photophysical properties from those of the isolated one. In order to harness the potential of the molecule-NP system, appropriate design guidelines are required. Here, we propose an inverse design method of the optimal molecule-NP systems and incident electric field for desired photophysical properties.

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