Toshiyuki Kida

We successfully fabricated rhombic plate-like microstructures composed of layered assemblies of head-to-head supramolecular dimers of 6-O-methylated and 6-O-ethylated α-cyclodextrins (6-Me-α-CD and 6-Et-α-CD, respectively). 6-Me-α-CD selectively extracted methyl elaidate (trans) over methyl oleate (cis) in methanol via microstructure formation driven by inclusion complexation between the 6-Me-α-CD dimer and fatty acid esters, whereas 6-Et-α-CD exhibited the opposite selectivity. These results demonstrate that subtle modulation of the alkyl chain length at the 6-O position of α-CD enables reversal of cis/trans selectivity in supramolecular extraction behavior. The origin of this selectivity was further elucidated by theoretical calculations based on density functional theory (DFT) and fragment molecular orbital (FMO) interaction energy analysis.

Circularly polarized luminescence (CPL) has attracted significant attention for applications in displays, data encryption, anti‐counterfeiting, and bioimaging. However, extending the emission lifetime beyond the second timescale remains a challenge. Here, we report circularly polarized long‐persistent luminescence (CP‐LPL) and the first evidence of circularly polarized photostimulated luminescence (CP‐PSL) in purely organic systems. Using the chiral emitter R/S ‐OBN‐Cz, we establish two complementary design strategies: (i) a three‐component Förster resonance energy transfer (FRET) system, where the energy of long‐lived charge‐separated states between the donor and the acceptor is transferred to the chiral dopant, and (ii) a two‐component upconversion system, where the locally excited state of chiral emitter is restored upon charge recombination. Both approaches result in CP‐LPL with mirror‐image CPL signals. Moreover, in the three‐component FRET system, trapped charges in the chiral dopant can be released upon near‐infrared stimulation, regenerating circularly polarized emission. This work establishes new proof of concept in chiroptical materials research, paving the way toward the practical applications in encrypted optical storage and advanced photonic devices.

Circularly polarized luminescence (CPL) has attracted significant attention for applications in displays, data encryption, anti-counterfeiting, and bioimaging. However, extending the emission lifetime beyond the second timescale remains a challenge. Here, we report circularly polarized long-persistent luminescence (CP-LPL) and the first evidence of circularly polarized photostimulated luminescence (CP-PSL) in purely organic systems. Using the chiral emitter R/S-OBN-Cz, we establish two complementary design strategies: (i) a three-component Förster resonance energy transfer (FRET) system, where the energy of long-lived charge-separated states between the donor and the acceptor is transferred to the chiral dopant, and (ii) a two-component upconversion system, where the locally excited state of chiral emitter is restored upon charge recombination. Both approaches result in CP-LPL with mirror-image CPL signals. Moreover, in the three-component FRET system, trapped charges in the chiral dopant can be released upon near-infrared stimulation, regenerating circularly polarized emission. This CP-PSL behavior expands the scope of CPL-active systems and opens new opportunities for encrypted optical storage and advanced photonic devices.

Chiral symmetry breaking (CSB) under nonequilibrium open conditions is a ubiquitous phenomenon in the universe, whereas molecular-level CSB is limited. Only the preferential enrichment and Viedma ripening that occur during the crystallization process from a solution are known. Herein, we discovered the third category of CSB, which is complete CSB within a single crystal. A racemic crystal of 3-(4-(benzo[d]thiazol-2-yl)phenyl)-10-propyl-10H-phenothiazine, a phenothiazine derivative with dynamic chirality, undergoes a single-crystal-to-single-crystal structural transition to a chiral crystal. Furthermore, the chirality after the transition is able to be controlled by solid-seeding of a chiral crystal. The resulting chiral single crystals exhibited circularly polarized luminescence (CPL) properties (g_lum = 8.9 × 10⁻⁴). This discovery provides a simple model of CSB and stimuli-responsive materials involving the CSB phenomenon.

A hydrogen-bonded network structure of 1,2,3-tris(4-carboxyphenyl)benzene, the last remaining derivative of the three isomeric derivatives, was revealed. Despite the geometric mismatch anticipated in hydrogen-bonded network formation, the obtained structure is shown to have formed both an ideal hydrogen-bonded dimer of carboxy groups and an infinite 2D network structure with 63-connected topology. A gas sorption experiment indicated that the activated crystal has micropores, although removal of the included solvent resulted in structural changes.

Thermally activated delayed fluorescence (TADF) materials possess exceptional photophysical properties. Organic scintillators utilizing TADF materials have shown great promise for applications requiring efficient radio-luminescence, owing to their high quantum efficiency and tunable emission properties. Previous studies demonstrated that polymer dots (P-dots) doped with TADF materials exhibit radio-luminescence under hard X-ray and electron beam excitation. However, the TADF materials used in these experiments were limited to limited color options, restricting their utility and hindering the exploration of multicolor radio-luminescence necessary for advanced applications. In this study, we successfully achieved multicolor radio-luminescence-blue, yellow, and red-by developing P-dots doped with TADF materials that emit across the visible spectrum. This breakthrough was demonstrated under excitation by hard X-rays, gamma rays, and electron beams. The ability to realize multicolor radio-luminescence is crucial, as it enables enhanced spatial and spectral resolution, which is vital for applications such as high-precision bio-imaging and multimodal sensing.

Chiral symmetry breaking (CSB) under the nonequilibrium open conditions is a ubiquitous phenomenon in the universe, whereas molecular-level CSB is limited. Only the preferential enrichment and Viedma ripening that occur during the crystallization process from a solution are known. Herein, we discovered the third category of CSB, which is complete CSB within a single crystal. A racemic crystal of 3-(4-(benzo[d]thiazol-2-yl)phenyl)-10-propyl-10H-phenothiazine, a phenothiazine derivative with chirality, undergoes a single-crystal-to-single-crystal structural transition to a chiral crystal. Furthermore, the chirality after the transition could be controlled by solid-seeding of a chiral crystal. The resulting chiral single crystals exhibited circularly polarized luminescence (CPL) properties (glum = 8.9 × 10−4). This discovery provide a simple model of CSB and stimuli-responsive materials involving the CSB phenomenon.

The ability to sense saccharides in aqueous media has attracted much attention in multidisciplinary sciences because the detection of ultrahigh concentrations of sugar chains associated with serious diseases could lead to further health promotion. However, there are notable challenges. In this study, a rhodamine-modified Curdlan (Rhod-Cur) chemosensor was synthesized that exhibited distinctive fluorescence "turn-on" responses. Rhod-Cur exhibited simultaneous sensitive and selective sensing of clinically useful acarbose with a good limit of detection (5 mu M) from among those of the saccharides examined. The (chir)optical properties of Rhod-Cur were elucidated using UV/vis, fluorescence, excitation, and circular dichroism spectroscopies; lifetime measurements and morphological studies using atomic force and confocal laser scanning microscopy and dynamic light scattering techniques revealed that the fluorescence "turn-on" behavior originates from globule-to-coaggregation conversion upon insertion of the oligosaccharides in the dynamic Cur backbone.

An amphiphilic Rose Bengal dye-based supramolecular nanosheet was fabricated, elucidating a distinct change in the photosensitization mechanism.