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DOSY Study on Dynamic Catenation: Self‐Assembly of a [3]Catenane as a Meta‐Stable Compound from Twelve Simple Components
Author(s) -
Hori Akiko,
Kumazawa Kazuhisa,
Kusukawa Takahiro,
Chand Dillip Kumar,
Fujita Makoto,
Sakamoto Shigeru,
Yamaguchi Kentaro
Publication year - 2001
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 - 10.1002/1521-3765(20011001)7:19<4142::aid-chem4142>3.0.co;2-5
Subject(s) - catenane , catenation , molar ratio , chemistry , molecule , supramolecular chemistry , crystallography , stereochemistry , organic chemistry , catalysis , dna , biochemistry
Synthesis of [2]catenane 6 has been successfully achieved by the combination of Pd complex 1 and pyridines 2 and 3 at a molar ratio of 2:1:1 in D 2 O. A mixture of square molecule 4 (prepared from 1 and 2 ) and macrocycle 5 (obtained from 1 and 3 ), in which the final ratio of 1, 2 , and 3 was kept 2:1:1 reorganizes in D 2 O/CD 3 OD (1:1) to form 6 within one day. However, the same mixture in D 2 O shows the formation of novel [3]catenane 7 along with the [2]catenane. In order to make 7 , the theoretical ratio of components 1, 2 , and 3 should be 3:1:2. Thus, deliberately maintaining such ratio of the above‐mentioned molecules, a higher proportion of the [3]catenane is observed in D 2 O as found from 1 H NMR spectra of the system. Reorganization of the twelve components to form [3]catenane is supported by studies with the DOSY method. This method is a first attempt to separate, from a mixture, either catenanes or any other supramolecular self‐assembly structures. CSI‐MS studies further support the assigned catenane super structures 6 and 7 . All the results indicate that the [2]catenane is thermodynamically the most stable structure, while the [3]catenane is a meta‐stable self‐assembly.