| 研究課題/領域番号 |
18K05247
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| 研究機関 | 沖縄科学技術大学院大学 |
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研究代表者 |
クスヌディノワ ジュリア 沖縄科学技術大学院大学, 錯体化学・触媒ユニット, 准教授 (90747544)
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| 研究期間 (年度) |
2018-04-01 – 2021-03-31
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| キーワード | mechanoresponsive / mechanophore / polymers |
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| 研究実績の概要 |
During this fiscal year, the progress was achieved in the directions of (a) elucidation of the underlying mechanism for mechanoresponse in photoluminescent copper complexes as mechanophores; (b) optimization and development of more air-stable Cu-based photoluminescent model complexes; (c) design of cross-linked polymers with incorporated Cu-based mechanophores that show significantly improved sensitivity of mechanoresponse to stretching, and (d) initial study of Ni complexes as potential mechanochromic probes. One publication resulted from this work and two more manuscripts are currently in preparation. Details are given below:
(a) A series of Cu complexes with pyridinophane ligands were prepared with variable steric bulk and established a strong correlation between dynamic conformational exchange controlled by the steric bulk and their photoluminescent properties. This explains the mechanism of mechanoresponse of the pyridinophane-based probes
(b) Model Cu complexes with N-heterocyclic carbenes were prepared and fully characterized that show improved air stability and bright photoluminescence even in polar solvents
(c) These Cu complexes were used as mechanophores in cross-linked polymers and demostrated improved sensitivity of the response to even small mechanical stress
(d) We screened several types of Ni complexes as potential mechanichromic probes, however, the initial study shows that these complexes either show weak response or low stability.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
The project progressed smoothly according to the original plan and resulted in one published paper. Two more manuscripts are currently in preparation.
According to the original plan, copper photoluminescent mechanophores were developed with improved sensitivity to air. Model complexes were stable in air in the solid state indefinitely, and showed high stability in solution for several days. Polymer films with covalently incorporated complexes showed high stability over at least 14 days with only slight decrease of the quantum yield. The cross-linked materials were significantly more sensitive than previously reported polyurethane systems showing response even at small strain (<50%) and stress (< 1MPa). The changes in photoluminescence can be detected not only through spectroscopic measurements, but also by direct imaging (high speed camera).
The mechanism of mechanoresponse in copper-based mechanophores was elucidated through a series of model complexes. It will help to further develop new types of coordination complex-based mechanophores. The established correlation between conformational lability and photophysical properties shows that this can be used as a general principle for the design of other ligands that will demonstrate the same function in the future.
Initial studies with Ni complexes will be useful to optimize systems with different metals other than copper. This study showed that Ni complexes may suffer from reduced stability, and their replacement with more stable analogs may be necessary, helping to develop the plan for the following year.
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| 今後の研究の推進方策 |
The following plan will be used:
(a) finalize the study of new Cu-N-heterocyclic carbene-based mechanophores in cross-linked polymers with improved sensitivity to weak mechanical stress and small deformations. Currently the manuscript is in preparation. Stress-strain curves will be measured to characterize mechanical properties. DSC studies will be performed. The final measurements will be necessary to show optical imaging results demonstrating luminescence intensity change in response to tensile stretching. We also plan to apply for a provisional patent.
(b) Study mechanism of mechanoresponse in model complexes of Cu with N-heterocyclic carbenes through detailed photophysical studies. Manuscript is currently in preparation. The complexes will be characterized by dynamic NMR studies to establish the role of conformational exchange on the photophysical properties. The cross-linked polymers will be prepared, and their performance will be compared depending on the nature of subtituents at the ligand.
(c) Develop colorimetric sensors based on polymer-incorporated Cu complexes to sense gaseous molecules (ethylene, etc) by coordination to Cu center; test mechanical response. Initial studies show that polymer-incorporated Cu complexes react in a sensitive manner with ethylene showing color changes. Reversibility of this process will be studied. If reversible, it can lead to development of fast reversible sensor of ethylene gas or other terminal alkenes present in gas phase or solution.
(d) Further screen pyridinophane model complexes with different metals (Ni, Pd, Co).
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| 次年度使用額が生じた理由 |
The actual expenditure in the fiscal year was overall the same as planned, with small amount remaining. The remaining amount of 41,460 yen is to be used for purchasing chemicals and research materials in the next fiscal year.
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