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Humidity‐Responsive ON/OFF Switching of Gas Inclusion by Using Cooperative Opening/Closing of Heterogeneous Crystalline Cavities in a Peptide Ni II Macrocycle
Author(s) -
Miyake Ryosuke,
Kuwata Chika,
Ueno Manami,
Yamada Teppei
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201704809
Subject(s) - adsorption , water vapor , humidity , inclusion (mineral) , peptide , chemistry , chemical engineering , crystallography , organic chemistry , mineralogy , thermodynamics , biochemistry , physics , engineering
Humidity‐responsive ON/OFF switching of CO 2 inclusion, associated with cooperative structural changes of heterogeneous cavities in crystalline peptide Ni II macrocycles, 1 ⋅NO 3 , is demonstrated. The structural transformation between an “open form” and a “closed form” was caused by reversible water uptake into one of the cavities. The adsorption behavior of CO 2 was studied with and without water vapor, combined with gas‐composition analysis by using gas chromatography. The studies revealed that the open form of 1 ⋅NO 3 adsorbs CO 2 gas up to 34 g mol −1 , whereas the closed form adsorbs only a negligible amount of CO 2 gas. Also, structural studies (X‐ray and IR spectroscopies) and investigation of water‐content dependence of CO 2 adsorption revealed that the switching of gas inclusion occurred abruptly over a narrow range of water‐vapor pressure and was caused by the cooperative opening of vacant space to give the open form due to the structural transformation by water uptake.