2016 Fiscal Year Annual Research Report
光に応答するミクロ孔を利用した異方的能動輸送膜の開発
| Project/Area Number |
15J10616
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| Research Institution | The University of Tokyo |
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Principal Investigator |
黄 虎彪 東京大学, 工学系研究科, 特別研究員(DC1)
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| Project Period (FY) |
2015-04-24 – 2018-03-31
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| Keywords | Azobenzene / Metal-organic frameworks / gas soprtion / polarity / photomoduable / diffusion rate constant |
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| Outline of Annual Research Achievements |
The research project in this year is a fundamental study of kinetic diffusion of gaseous molecules in a zirconium-based MOF appended with azobenzene units (AzoMOF). The key points are summarized as follows:
(1) Azobenzene-containing ligands (AzoLH2) are synthesized and their photochemical properties are studied by electronic absorption spectra, proton NMR, etc. (2) AzoMOFs are synthesized by AzoLH2 and zirconium ions through a solvothermal reaction. The photochemical properties of AzoMOF are confirmed by diffuse reflectance spectroscopy and proton NMR. Upon 30-min irradiation with UV light (365 ± 10 nm), the photostationary state of AzoMOF is achieved with cis-isomer content of 21%. (3) AzoMOF provides the first platform to modulate the diffusion kinetics of CO2 by photochemical alteration of the interior polarity of nanochannels, rather than steric effect. The use of a polarity-sensitive probe, erythrosine B, together with Ar as an apolar gaseous guest with a comparable kinetic diameter to that of CO2, nicely supported the above conclusion. (4) By using the double exponential model, I found that the diffusion rate constant of CO2 with quadrupole moment (–14.9 × 10–40 C m2) is greatly influenced upon trans/cis isomerization of azobenzene units inside AzoMOF. In sharp contrast, this difference in diffusion rate constant is not observed in the case of Ar, although both CO2 and Ar are apolar.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
I achieved the first example to realize the control over the diffusion of gas molecules with different physical properties, particularly, dipole moment, in an azobenzene-containing MOFs (AzoMOFs). The synthesis of AzoMOF was successfully synthesized within six month by solvothermal reactions; and its structures and properties were throughly investigated. What is more importantly is that this AzoMOF showed great potentiality in modulating the diffusion behavior of gas molecules with varied physical properties (CO2 and Ar in this study).
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| Strategy for Future Research Activity |
In future, I am planing to modify the substituents on pendant azobenzene groups in the AzoMOF to realize the modulation of structures and properties of AzoMOF by visible light irradiation instead of UV light, because the use of visible light shall be more efficient to access to the inner part of AzoMOF crystals; therefore the isomerization efficacy should be higher that 21% in the current case. Also, I am interesting in exploring the change of pore environment induced by photo-isomerization of azobenzene groups on the organic vapors with different physical properties, in order to maximize the applications of AzoMOF, such as separation of organic molecules.
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Research Products
(2 results)
