Title :

Assessing the structure of octastate molecular switches using h-1 nmr density functional theory calculations

Author(s) :

Mohamed, Slim Hadj [Auteur]
Université de Sfax - University of Sfax
Quertinmont, Jean [Auteur]
Université de Namur [Namur] [UNamur]
Delbaere, Stephanie [Auteur]
Laboratoire de Spectrochimie et Raman (LASIR) - UMR 8516
Laboratoire Avancé de Spectroscopie pour les Intéractions la Réactivité et l'Environnement - UMR 8516 [LASIRE]
Sanguinet, Lionel [Auteur]
MOLTECH-Anjou
Champagne, Benoit [Auteur]
Université de Namur [Namur] [UNamur]

Journal title :

The journal of physical chemistry: C, Nanomaterials and interfaces

Abbreviated title :

J. Phys. Chem. C

Volume number :

122

Pages :

1800-1808

Publication date :

2018-01-25

ISSN :

1932-7447

HAL domain(s) :

Sciences du Vivant [q-bio]

English abstract : [en]

Density functional theory calculations are used to reveal the relationships between the structures, energies, and NMR signatures of an octastate molecular switch composed of a dithienylethene (DTE) unit covalently linked ...
Show more >Density functional theory calculations are used to reveal the relationships between the structures, energies, and NMR signatures of an octastate molecular switch composed of a dithienylethene (DTE) unit covalently linked to an indolino[2,1-b]oxazolidine (BOX) moiety through an ethylenic junction. Both the DTE and BOX moieties can adopt open or closed forms. The ethylenic junction can be Z or E, but the latter has been confirmed to be, by far, more stable than the former for all BOX/DTE combinations. In addition, when the DTE is open, the two thienyl units can fold to form parallel conformers, by opposition to the antiparallel or unfolded conformers. Usually parallel conformers present a higher energy than the antiparallel ones, but in the case of compound 2 having a bulky substituent (R = pPh-SMe) on the terminal thienyl group, the enthalpy of one conformer is very close (1–2 kJ mol–1) to that of the most stable antiparallel one, making photocyclization less efficient. These conformational differences and the presence of parallel DTE forms have been substantiated by analyzing experimental 1H NMR chemical shifts in light of their calculated values. These 1H NMR chemical shift calculations led to the following statements: (i) Going from state I (DTE open, BOX closed) to state II (both DTE and BOX are open) the H8 proton of compound 1 (R = Me) is deshielded by ∼0.15 ppm. (ii) The deshielding of H8 proton of compound 2 is larger and attains 0.41 ppm whereas H7 is more shielded by 0.11 ppm. (iii) Then, going from compound 1 to compound 2 leads to deshielding of both H7 and H8 protons. As a consequence, the difference of photochromism gating efficiency among compounds 1, 2, and 3 (R = pPh-OMe) can be attributed to the stabilization of parallel conformer due to an establishment of an intramolecular interaction with BOX opening.Show less >

Language :

Anglais

Audience :

Internationale

Popular science :

Non

Administrative institution(s) :

CHU Lille
Inserm
Université de Lille

Collections :

• Laboratoire Avancé de Spectroscopie pour les Intéractions la Réactivité et l'Environnement (LASIRE) - UMR 8516
• Lille Neurosciences & Cognition (LilNCog) - U 1172

Research team(s) :

Brain Biology & Chemistry (BBC)

Submission date :

2021-06-23T11:42:01Z
2021-11-16T07:58:01Z
2024-02-14T08:50:24Z
2024-02-14T13:19:50Z
2024-02-14T13:20:27Z
2024-02-14T13:21:41Z