Quantum dots (QDs) are semiconductor nanocrystals with size of less than several tens of nanometers, which show unique physicochemical properties due to the quantum size effect. The Nobel Prize in Chemistry 2023 has been conferred upon Prof. Moungi G. Bawendi, Prof. Louis E. Brus, and Prof. Alexei I. Ekimov in recognition of their groundbreaking contributions to the discovery and development of quantum dots. In this review, we introduce a historical overview of the chemical synthesis of quantum dots, made by these Nobel laureates, and report on the recent progress of less-toxic QDs composed of multinary semiconductors. The tunability of physicochemical properties of QDs by their size and composition has been attracting scientific curiosity and technological interest for developing novel applications, such as photoluminescent materials, bio-markers, and LEDs.
Structural color is the color that results from the optical interaction between light and microstructure. In nature, natural melanin plays an important role in bright structural color. For example, the structural color of peacock feathers is attributed to the periodic arrangement of melanin granules inside the feathers, with the black granules effectively absorbing scattered light, resulting in a bright structural color. Recently, polydopamine has attracted much attention as a melanin-mimetic material. In this paper, I summarize recent studies on structural coloration using melanin particles based on polydopamine. Potential applications, such as ink materials utilizing the bright structural color realized by melanin materials, are also outlined.
This paper introduces the advantages of high-energy-resolution fluorescence detected (HERFD) X-ray absorption spectroscopy and its feasibility for in situ observation to elucidate the properties of cluster materials. The HERFD mode enables accurate and quantitative evaluation of ligand effects in ligand-protected Au clusters. The HERFD mode also reveals the fine ligand field splitting of Ta oxide clusters in the solution state and demonstrates that it is applicable to trace the electronic structure changes during molecular adsorption.