Subnanometer noble metal clusters have enormous potential, mainly for catalytic applications. Because a difference of only one atom may cause significant changes in their reactivity, a preparation method with atomic-level precision is essential. Although such a precision with enough scalability has been achieved by gas-phase synthesis, large-scale preparation is still at the frontier, hampering practical applications. We now show the atom-precise and fully scalable synthesis of platinum clusters on a milligram scale from tiara-like platinum complexes with various ring numbers (n = 5–13). Low-temperature calcination of the complexes on a carbon support under hydrogen stream affords monodispersed platinum clusters, whose atomicity is equivalent to that of the precursor complex. One of the clusters (Pt₁₀) exhibits high catalytic activity in the hydrogenation of styrene compared to that of the other clusters. This method opens an avenue for the application of these clusters to preparative-scale catalysis.

Superatoms, clusters that mimic the properties of elements different to those of which they are composed, have the potential to serve as building blocks for unprecedented materials with tunable properties. The development of a method for the solution-phase synthesis of superatoms would be an indispensable achievement for the future progress of this research field. Here we report the fabrication of aluminum clusters in solution using a dendrimer template, producing Al₁₃⁻, which is the most well-known superatom. The Al₁₃⁻ cluster is identified using mass spectrometry and scanning transmission electron microscopy, and X-ray photoelectron spectroscopy is used to measure the binding energies. The superatomic stability of Al₁₃⁻ is demonstrated by evaluating its tendency toward oxidation. In addition, the synthesis of Al₁₃⁻ in solution enables electrochemical measurements, the results of which suggest oxidation of Al₁₃⁻. This solution-phase synthesis of Al₁₃⁻ superatoms has a significant role for the experimental development of cluster science.

10,10′-Diphenyl-9,9′-bianthracene (PPBA) does not generate T₁ excitons in OLEDs, and RISC at a higher excited state is suggested.

The periodic table has always contributed to the discovery of a number of elements. Is there no such principle for larger-scale substances than atoms? Many stable substances such as clusters have been predicted based on the jellium model, which usually assumes that their structures are approximately spherical. The jellium model is effective to explain subglobular clusters such as icosahedral clusters. To broaden the scope of this model, we propose the symmetry-adapted orbital model, which explicitly takes into account the level splittings of the electronic orbitals due to lower structural symmetries. This refinement indicates the possibility of an abundance of stable clusters with various shapes that obey a certain periodicity. Many existing substances are also governed by the same rule. Consequently, all substances with the same symmetry can be unified into a periodic framework in analogy to the periodic table of elements, which will act as a useful compass to find missing substances.

We now report the first direct observation of the fluxional nature in which the four-atomic platinum cluster (Pt ₄ ) randomly walks through several isomers.

To elucidate the high external quantum efficiency observed for organic light-emitting diodes using a bisanthracene derivative (BD1), non-radiative transition processes as well as radiative ones are discussed employing time-dependent density functional theory. It has been previously reported that the observed high external quantum efficiency of BD1 cannot be explained by the conventional thermally activated delayed fluorescence involving T₁ exciton nor triplet-triplet annihilation. The calculated off-diagonal vibronic coupling constants of BD1, which govern the non-radiative transition rates, suggest a fluorescence via higher triplets (FvHT) mechanism, which entails the conversion of a high triplet exciton generated during electrical excitation into a fluorescent singlet exciton. This mechanism is valid as long as the relaxation of high triplet states to lower states is suppressed. In the case of BD1, its pseudo-degenerate electronic structure helps the suppression. A general condition is also discussed for the suppression of transitions in molecules with pseudo-degenerate electronic structures.