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7 results on '"Hironobu Nakazawa"'

1. Amplification sensing manipulated by a sumanene-based supramolecular polymer as a dynamic allosteric effector

Author

Hiroaki Mizuno, Hironobu Nakazawa, Akihisa Miyagawa, Yumi Yakiyama, Hidehiro Sakurai, and Gaku Fukuhara

Subjects
Sumanene, Supramolecular polymer, Allosterism, Amplification sensing, Medicine, Science
Abstract

Abstract The synthesis of signal-amplifying chemosensors induced by various triggers is a major challenge for multidisciplinary sciences. In this study, a signal-amplification system that was flexibly manipulated by a dynamic allosteric effector (trigger) was developed. Herein, the focus was on using the behavior of supramolecular polymerization to control the degree of polymerization by changing the concentration of a functional monomer. It was assumed that this control was facilitated by a gradually changing/dynamic allosteric effector. A curved-π buckybowl sumanene and a sumanene-based chemosensor (SC) were employed as the allosteric effector and the molecular binder, respectively. The hetero-supramolecular polymer, (SC·(sumanene)n), facilitated the manipulation of the degree of signal-amplification; this was accomplished by changing the sumanene monomer concentration, which resulted in up to a 62.5-fold amplification of a steroid. The current results and the concept proposed herein provide an alternate method to conventional chemosensors and signal-amplification systems.

Published
2024
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2. Pentagon-Fused Sumanenes on the Aromatic Peripheries en Route to the Bottom-Up Synthesis of Fullerenes

Author

Hidehiro Sakurai, Hironobu Nakazawa, Yuta Uetake, and Yumi Yakiyama

Subjects
Organic Chemistry
Abstract

Bowl-shaped π-conjugated sumanenyltriamines were successfully synthesized in a one-step reaction from bromomethylsumanene. This molecule represents an example of hemiazafullerene (C54N6 fragment) with six isolated pentagons. Its single-crystal X-ray structural analysis showed the formation of one-dimensional columnar structures incorporating chloroform. The hemifullerene (C30 fragment) was also synthesized when the nucleophile was changed to dimethylmalonate.

Published
2022

3. Sumanene-Stacked Supramolecular Polymers. Dynamic, Solvation-Directed Control

Author

Hiroaki Mizuno, Hironobu Nakazawa, Makoto Harada, Yumi Yakiyama, Hidehiro Sakurai, and Gaku Fukuhara

Abstract

Supramolecular polymer chemistry has recently garnered considerable attention in multidisciplinary science, however, the mutual choice of supramolecular hosts and monomer units has yet to be demonstrated on a trial-and-error basis. Curved-pi-buckybowls appear to be good “seeds” for supramolecular polymers, however, the very fast bowl-to-bowl inversion in the solution hampers their wide usage. In this study, we found that a pristine buckybowl, sumanene, can form solution-state supramolecular polymers via bowl-to-bowl inversion. We also demonstrated that sumanene supramolecular polymers can be dynamically controlled by external stimuli, in which solvation plays a significant role. This study not only provides new guidelines for the rational design of supramolecular polymers, particularly for the use of buckybowls, but also presents interesting dynamic behaviors of supramolecular polymerization.

Published
2023

4. Synthesis of Sumanene‐fused Acenes

Author

Hironobu Nakazawa, Akinobu Ohya, Yuto Morimoto, Yuta Uetake, Naohiko Ikuma, Kenji Okada, Masayoshi Nakano, Yumi Yakiyama, and Hidehiro Sakurai

Subjects
Organic Chemistry
Published
2022

5. Theoretical Study on Singlet Fission Dynamics in Sumanene-Fused Acene Dimers

Author

Kenji Okada, Yuta Uetake, Masayoshi Nakano, Hironobu Nakazawa, Hidehiro Sakurai, and Hajime Miyamoto

Subjects
Physics, Class (set theory), Exciton, 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Molecular physics, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Condensed Matter::Materials Science, chemistry.chemical_compound, General Energy, chemistry, Quantum master equation, Singlet fission, Physics::Atomic and Molecular Clusters, Sumanene, Molecule, Density functional theory, Physical and Theoretical Chemistry, 0210 nano-technology, Acene
Abstract

We investigate the potential of sumanene-fused acenes as a novel class of highly efficient singlet fission (SF) candidates by density functional theory (DFT) calculations and exciton dynamics simul...

Published
2020

6. Sumanene Hexaester: An Electron-Deficient Buckybowl

Author

Takanori Fukushima, Hironobu Nakazawa, Yumi Yakiyama, Yuta Uetake, Takashi Kajitani, Hideaki Toda, and Hidehiro Sakurai

Subjects
010405 organic chemistry, Chemistry, Organic Chemistry, Electron, 010402 general chemistry, Photochemistry, 01 natural sciences, Catalysis, 0104 chemical sciences, Solvent, chemistry.chemical_compound, Yield (chemistry), Sumanene, Formate, Emission spectrum
Abstract

2,3,5,6,8,9-Hexakis(phenoxycarbonyl)sumanene, a hexa­substituted sumanene with CO2Ph groups at the peripheral aromatic carbons, was successfully prepared in good yield by Pd-catalyzed phenoxycarbonylation­ using a solvent of phenyl formate. Single-crystal X-ray structural analysis of this compound revealed the formation of a one-dimensional columnar structure, stacked in a staggered manner. The UV and emission spectra of this showed clear red-shifts compared with those of pristine sumanene, indicating the extension of the conjugation system.

Published
2019

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