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Watanabe, Taku*; Maejima, Yui*; Ueda, Yuki; Motokawa, Ryuhei; Takabatake, Ai*; Takeda, Shinichi*; Fudoji, Hiroshi*; Kishikawa, Keiki*; Koori, Michinari*
Langmuir, 41(34), p.22762 - 22773, 2025/09
Times Cited Count：5 Percentile：52.00(Chemistry, Multidisciplinary)The assembled structures of melanin particles, i.e., colloidal particles coated with a melanin-like polydopamine (PDA) layer, create vivid structural colors. While the thickness of the PDA layer influences the particle arrangement and optical properties, the underlying mechanism has remained controversial. We demonstrate that the water swelling characteristics of PDA are crucial factors governing the dispersion and aggregation of these particles in solution. Detailed comparisons between dry and wet conditions revealed that the PDA layer readily absorbs water molecules, which leads to significant swelling in the thicker layers. The swelling of the PDA layers determined whether the particles remained dispersed or partially aggregated in the water, ultimately controlling the particle arrangement in the dry state once the water evaporated. These findings provide insights into the self-assembly of colloidal particles and offer a strategy for tuning the periodic particle order. This feature is pivotal for various applications in optical and sensing technologies.
Hisamatsu, Shugo; Suzuki, Shinichi; Komoto, Shigeo*; Kishikawa, Keiki*; Yamamoto, Yusuke*; Motokawa, Ryuhei; Yaita, Tsuyoshi
Tetrahedron, 73(27-28), p.3993 - 3998, 2017/07
Times Cited Count：19 Percentile：58.83(Chemistry, Organic)Motokawa, Ryuhei; Taniguchi, Tatsuo*; Kumada, Takayuki; Iida, You*; Aoyagi, Shota*; Sasaki, Yusuke*; Kori, Michinari*; Kishikawa, Keiki*
Macromolecules, 49(16), p.6041 - 6049, 2016/08
Times Cited Count：32 Percentile：69.70(Polymer Science)Komoto, Shigeo*; Chuko, Tomotaka*; Hisamatsu, Shugo; Okuda, Yasuhiro*; Masu, Hyuma*; Takahashi, Masahiro*; Kishikawa, Keiki*
Crystal Growth & Design, 15(6), p.2723 - 2731, 2015/05
Times Cited Count：21 Percentile：78.59(Chemistry, Multidisciplinary)Piezoluminescence and liquid crystallinity of anthracene-based bispyridinium salts were investigated in stimulus responsive luminescent organic crystals and luminescent ionic liquid crystals. The salts possess an anthracene moiety as a fluorophore in their center, and the pyridiniums attached to the anthracene moiety are substituted with trialkoxybenzyl groups. Single crystals of the salts bearing two trimethoxybenzyl groups were obtained as solvates. Ethyl acetate, acetone, and dioxane solvates of the chlorides have almost the same crystal structures with one-dimensional channels. Grinding of the solvated crystals caused the extrusion of the included solvent molecules, which resulted in the red shifts of their fluorescence in the solid state. Tris(octyloxy)benzyl and tris(dodecyloxy)benzyl derivatives exhibited rectangular columnar liquid crystals upon being heated for their bromide and tetrafluoroborate salts and upon being cooled for their hexafluorophosphate salts.
Hisamatsu, Shugo; Masu, Hyuma*; Takahashi, Masahiro*; Kishikawa, Keiki*; Komoto, Shigeo*
Crystal Growth & Design, 15(5), p.2291 - 2302, 2015/04
Times Cited Count：92 Percentile：98.18(Chemistry, Multidisciplinary)Anthracene derivatives possessing a carbamate group and an ester group at their 9- and 10-positions, respectively, were prepared to furnish pairwise packing of anthracene fluorophores in their crystal structures. They were nonluminescent in ethanol solution and showed AIE (aggregation-induced emission) in aqueous ethanol solution and in solid state. Crystal structure analysis of them showed that the H-bonding networks involved in their crystal structures could be classified into four patterns, H-bonding between the carbamate and the ester carbonyl (motifA), H-bonding between the carbamate and the ester oxygen atom (motif B), H-bonded cyclic dimer of carbamate moieties (motif C), and H-bonded chain among carbamate moieties (motif D). Compounds with pairwisely packed anthracene fluorophores showed dimer emission with the longer fluorescence wavelength than others without the pair formation.
