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Co‐conformational Exchange Triggered by Molecular Recognition in a Di(acylamino)pyridine‐Based Molecular Shuttle Containing Two Pyridine Rings at the Macrocycle
Author(s) -
MartinezCuezva Alberto,
CarroGuillen Fernando,
Pastor Aurelia,
MarinLuna Marta,
Orenes RaulAngel,
Alajarin Mateo,
Berna Jose
Publication year - 2016
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201501060
Subject(s) - pyridine , chemistry , molecular recognition , stereochemistry , photochemistry , crystallography , molecule , medicinal chemistry , organic chemistry
We describe the incorporation of endo ‐pyridine units into the tetralactam ring of di(acylamino)pyridine‐based rotaxanes. This macrocycle strongly associates with the linear interlocked component as confirmed by X‐ray diffraction studies of rotaxane 2 b . Dynamic NMR studies of 2 b in solution revealed a rotational energy barrier that was higher than that of the related rotaxane 2 a , which lacks of pyridine rings in the macrocycle. The macrocycle distribution of the molecular shuttle 4 b , containing two endo ‐pyridine rings, shows that the major co‐conformer is that with the cyclic component sitting over the di(acylamino)pyridine station. DFT calculations also support the marked preference of the ring for occupying the heterocyclic binding site. The association of N ‐hexylthymine with the di(acylamino)pyridine binding site of 4 b led to the formation of a rare ‘S’‐shaped co‐conformer in which the tetralactam ring interacts simultaneously with both stations of the thread.