An Isolable, Photoswitchable N-Heterocyclic Carbene: On-Demand Reversible Ammonia Activation.
Angew Chem Int Ed Engl
; 54(39): 11559-63, 2015 Sep 21.
Article
em En
| MEDLINE
| ID: mdl-26274507
ABSTRACT
The first isolable, photoswitchable N-heterocyclic carbene was synthesized and found to undergo reversible electrocyclic isomerization upon successive exposure to UV and visible radiation. The UV-induced ring closure afforded substantial changes to the electronic structure of the dithienylethene-based NHC, as evidenced by changes in the corresponding UV/Vis absorption and (13)Câ
NMR spectra. Likewise, molecular orbital calculations revealed diminished electron density at the carbene nucleus upon photocyclization, consistent with the enhanced electrophilicity displayed by the ring-closed form. The photoswitchable NHC was successfully switched between its ring-opened and ring-closed states with high fidelity over multiple cycles. Furthermore, the ring-closed isomer was found to undergo facile N-H bond activation, allowing for the controlled capture and release of ammonia upon cycling between its isomeric states.
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MEDLINE
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En
Ano de publicação:
2015
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Article