DOSY study on dynamic catenation: self-assembly of a [3]catenane as a meta-stable compound from twelve simple components.
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 D20. 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 D2O/CD3OD (1:1) to form 6 within one day. However, the same mixture in D2O 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 D2O as found from 1H 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.
Hori
A
A
Department of Applied Chemistry, Graduate School of Engineering, Nagoya University and CREST, Japan Science and Technology Corporation.
Kumazawa
K
K
Kusukawa
T
T
Chand
D K
DK
Fujita
M
M
Sakamoto
S
S
Yamaguchi
K
K
D004247:DNA / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry; D010165:Palladium / Q000737:chemistry; D010984:Platinum / Q000737:chemistry; D011725:Pyridines / Q000138:chemical synthesis / Q000737:chemistry*
D009942:Organometallic Compounds; D011725:Pyridines; D010984:Platinum; D010165:Palladium; D004247:DNA