An inverse opal structure was created using artificial melanin particles composed of a polystyrene core and a polydopamine shell as the template. The melanin-mimicking polydopamine that remained inside the inverse opal structure effectively absorbed multiple scattered light, producing bright structural color that was reversibly changed by solvent penetration.

Holmium (Ho) is a lanthanide element with a high magnetic moment. Here, we create an amorphous metalorganic framework (MOF) that has no long-range periodic order but retains the basic components of MOF by using isophthalic acid as an organic linker and Ho as a metal species. The resulting spherical Ho-MOF particles disperse well in a solvent and exhibit excellent magnetic properties in response to magnets. Since Ho has almost no coloring, Ho-MOF particles are a colorless magnetic material, unlike conventional iron oxide particles. Taking advantage of the colorless property, the selective adsorption of dyes on Ho-MOF particles can be easily visually confirmed by magnetically separating the particles. In addition, present versatile processes that enable adaptation of lanthanide elements other than Ho enable the development of colorless multifunctional MOF particles.

No abstract

No abstract

Uniform-sized amorphous hydrous titania particles (HTPs) with nonporous or porous surface were prepared and subjected to hot-water or hydrothermal treatment to induce crystallisation of the titania phase for preparing porous titania particles with high specific surface area (SSA) and outer diameter in a micron order. Porous HTPs were crystallised under milder treatment conditions than those required to crystallise nonporous spherical HTPs. This difference was attributed to the difference in the polycondensation states of hydrous titania. The SSA of the porous titania particles crystallised by hot-water treatment at 80°C for 24 h was 216 m 2 g −1 , despite their micron-order particle size. This simple method can synthesise highly functional titania particles at low temperatures and is a generalpurpose method for preparing porous particles for use as adsorbents, catalysts and catalyst supports.