title: Co-conformational Exchange Triggered by Molecular Recognition in a Di(acylamino)pyridine-Based Molecular Shuttle Containing Two Pyridine Rings at the Macrocycle.
abstract: 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.
authors.affiliation: Departamento de Química Organica, Facultad de Quimica, Regional Campus of International Excellence "Campus Mare Nostrum", Universidad de Murcia, E-30100, Murcia, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Martinez-Cuezva
authors.affiliation: Departamento de Química Organica, Facultad de Quimica, Regional Campus of International Excellence "Campus Mare Nostrum", Universidad de Murcia, E-30100, Murcia, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Carro-Guillen
authors.affiliation: Departamento de Química Organica, Facultad de Quimica, Regional Campus of International Excellence "Campus Mare Nostrum", Universidad de Murcia, E-30100, Murcia, Spain.
authors.forename: Aurelia
authors.initials: A
authors.lastname: Pastor
authors.affiliation: Instituto de Química Médica (CSIC), Juan de la Cierva 3, E-28006, Madrid, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Marin-Luna
authors.affiliation: SAI, Universidad de Murcia, E-30100, Murcia, Spain.
authors.forename: Raul-Angel
authors.initials: RA
authors.lastname: Orenes
authors.affiliation: Departamento de Química Organica, Facultad de Quimica, Regional Campus of International Excellence "Campus Mare Nostrum", Universidad de Murcia, E-30100, Murcia, Spain.
authors.forename: Mateo
authors.initials: M
authors.lastname: Alajarin
authors.affiliation: Departamento de Química Organica, Facultad de Quimica, Regional Campus of International Excellence "Campus Mare Nostrum", Universidad de Murcia, E-30100, Murcia, Spain. ppberna@um.es.
authors.forename: Jose
authors.identifier: 0000-0001-7775-3703
authors.initials: J
authors.lastname: Berna
keywords: hydrogen bonds; molecular devices; molecular recognition; rotaxanes; template synthesis