Encapsulation of Aromatic Guests in the Bisporphyrin Cavity of a Double-Stranded Spiroborate Helicate: Thermodynamic and Kinetic Studies and the Encapsulation Mechanism.
J Org Chem
; 86(15): 10501-10516, 2021 08 06.
Article
en En
| MEDLINE
| ID: mdl-34282918
ABSTRACT
A double-stranded spiroborate helicate bearing a bisporphyrin unit in the middle forms an inclusion complex with electron-deficient aromatic guests that are sandwiched between the porphyrins. In the present study, we systematically investigated the effects of size, electron density, and substituents of a series of aromatic guests on inclusion complex formations within the bisporphyrin. The thermodynamic and kinetic behaviors during the guest-encapsulation process were also investigated in detail. The guest-encapsulation abilities in the helicate increased with the increasing core sizes of the electron-deficient aromatic guests and decreased with the increasing bulkiness and number of substituents of the guests. Among the naphthalenediimide derivatives, those with bulky N-substituents at both ends hardly formed an inclusion complex. Instead, they formed a [2]rotaxane-like inclusion complex through the water-mediated dynamic B-O bond cleavage/reformation of the spiroborate groups of the helicate, which enhanced the conformational flexibility of the helicate to enlarge the bisporphyrin cavity and form an inclusion complex. Based on the X-ray crystal structure of a unique pacman-like 11 inclusion complex between the helicate and an ammonium cation as well as the molecular dynamics simulation results, a plausible mechanism for the inclusion of a planar aromatic guest within the helicate is also proposed.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Electrones
/
Simulación de Dinámica Molecular
Idioma:
En
Revista:
J Org Chem
Año:
2021
Tipo del documento:
Article
País de afiliación:
Japón
Pais de publicación:
EEUU
/
ESTADOS UNIDOS
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ESTADOS UNIDOS DA AMERICA
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EUA
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UNITED STATES
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UNITED STATES OF AMERICA
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US
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USA