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Ousaka N, Itakura M, Nagasaka A, Ito M, Hattori T, Taura D, Ikai T, Yashima E. Water-Mediated Reversible Control of Three-State Double-Stranded Titanium(IV) Helicates. J Am Chem Soc 2021; 143:4346-4358. [PMID: 33688731 DOI: 10.1021/jacs.0c13351] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
A stimuli-responsible reversible structural transformation is of key importance in biological systems. We now report a unique water-mediated reversible transformation among three discrete double-stranded dinuclear titanium(IV) achiral meso- and chiral rac-helicates linked by a mono(μ-oxo) or a bis(μ-hydroxo) bridge between the titanium ions through hydration/dehydration or its combination with a water-mediated dynamic cleavage/re-formation of the titanium-phenoxide (Ti-OPh) bonds. The bis(μ-hydroxo) bridged titanium(IV) meso-helicate prepared from two tetraphenol strands with titanium(IV) oxide was readily dehydrated in CD3CN containing a small amount of water upon heating, accompanied by Ti-OPh bond cleavage/re-formation catalyzed by water, resulting in the formation of the mono(μ-oxo)-bridged rac-helicate, which reverted back to the original bis(μ-hydroxo)-bridged meso-helicate upon hydration in aqueous CD3CN. These reversible transformations between the meso- and rac-helicates were also promoted in the presence of a catalytic amount of an acid, which remarkably accelerated the reactions at lower temperature. Interestingly, in anhydrous CD3CN, the bis(μ-hydroxo)-bridged meso-helicate was further slowly converted to a different helicate, while its meso-helicate framework was maintained, namely the mono(μ-oxo)-bridged meso-helicate, through dehydration upon heating and its meso to meso transformation was significantly accelerated in the presence of cryptand[2.2.1], which contributes to removing Na+ ions coordinated to the helicate. Upon cooling, the backward meso to meso transformation took place via hydration. Hence, three different, discrete double-stranded chiral rac- and achiral meso-titanium(IV) helicates linked by a mono(μ-oxo) or a bis(μ-hydroxo) bridge were successfully generated in a controllable manner by a change in the water content of the reaction media.
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Affiliation(s)
- Naoki Ousaka
- Department of Molecular and Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan.,Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan
| | - Manabu Itakura
- Department of Molecular and Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan
| | - Akira Nagasaka
- Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan
| | - Masaki Ito
- Department of Molecular and Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan
| | - Tomonari Hattori
- Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan
| | - Daisuke Taura
- Department of Molecular and Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan.,Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan
| | - Tomoyuki Ikai
- Department of Molecular and Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan
| | - Eiji Yashima
- Department of Molecular and Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan.,Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan
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Ousaka N, Yashima E. Stimuli-responsive Molecular Springs Based on Single- and Multi-stranded Helical Structures. CHEM LETT 2021. [DOI: 10.1246/cl.200737] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Naoki Ousaka
- Molecular Engineering Institute, Kyushu Institute of Technology, Tobata-ku, Kitakyushu, Fukuoka 804-8550, Japan
| | - Eiji Yashima
- Department of Molecular and Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya, Aichi 464-8603, Japan
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Taura D, Wang X, Ito M, Yashima E. Selective formation of spiroborate-based double-stranded hetero-helicates assisted by donor–acceptor interactions. Org Chem Front 2021. [DOI: 10.1039/d1qo00286d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel spiroborate-based double-stranded hetero-helicate is selectively formed through donor–acceptor interactions between the central electron-rich porphyrin and electron-deficient naphthalene diimide units.
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Affiliation(s)
- Daisuke Taura
- Department of Molecular and Macromolecular Chemistry
- Graduate School of Engineering
- Nagoya University
- Nagoya 464-8603
- Japan
| | - Xiang Wang
- Department of Molecular and Macromolecular Chemistry
- Graduate School of Engineering
- Nagoya University
- Nagoya 464-8603
- Japan
| | - Masaki Ito
- Department of Molecular and Macromolecular Chemistry
- Graduate School of Engineering
- Nagoya University
- Nagoya 464-8603
- Japan
| | - Eiji Yashima
- Department of Molecular and Macromolecular Chemistry
- Graduate School of Engineering
- Nagoya University
- Nagoya 464-8603
- Japan
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