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Molecular Recognition of Hydrocarbon Guests by a Supramolecular Capsule Formed by the 4:4 Self‐Assembly of Tris(Zn 2+ –Cyclen) and Trithiocyanurate in Aqueous Solution
Author(s) -
Aoki Shin,
Suzuki Satoshi,
Kitamura Masanori,
Haino Takeharu,
Shiro Motoo,
Zulkefeli Mohd,
Kimura Eiichi
Publication year - 2012
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201100871
Subject(s) - cyclen , chemistry , aqueous solution , supramolecular chemistry , host–guest chemistry , decalin , molecule , tris , molecular recognition , cage , crystallography , stereochemistry , organic chemistry , biochemistry , mathematics , combinatorics , catalysis
We have previously reported that the trimeric Zn 2+ –cyclen complex (tris(Zn 2+ –cyclen), [Zn 3 L 1 ] 6+ ) and the trianion of trithiocyanuric acid (TCA 3− ) assembled in a 4:4 ratio to form a cuboctahedral supramolecular cage, [(Zn 3 L 1 ) 4 (TCA 3− ) 4 ] 12+ (hereafter referred to as a Zn–cage), in neutral aqueous solution (cyclen=1,4,7,10‐tetraazacyclododecane). Herein, we examined the molecular recognition of C 1 –C 12 hydrocarbons (C n H (2 n +2) ( n ≈1–12)), cyclopentane, cyclododecane, cis ‐decalin, and trans ‐decalin by the Zn–cage under normal atmospheric pressure. This cage complex was also able to encapsulate guest molecules that had larger volumes than that of the inner cavity of the Zn–cage, thereby suggesting that the inner shape of the Zn–cage was flexible. Computational simulations of Zn–cage–guest complexes provided support for this conclusion. Moreover, the solvent‐accessible surface areas ( SASA ) of the Zn–cage host, guest molecules, and the Zn–cage‐guest complexes were calculated and the data were used to explain the order of stability determined by the guest‐replacement experiments. The storage of volatile molecules in aqueous solution by the Zn–cage is also discussed.