Document Detail


Proton grease: an acid accelerated molecular rotor.
MedLine Citation:
PMID:  22320172     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
A molecular rotor was designed that rotates seven orders of magnitude faster upon protonation. The quinoline rotor is based on a rigid N-arylimide framework that displays restricted rotation due to the severe steric interaction between the imide carbonyls and the quinoline nitrogen. At rt (23 °C), the rotor rotates slowly (t1/2 = 26 min, ΔG‡ = 22.2 kcal/mol). However, upon addition of 3.5 equiv of acid the rotor rotates rapidly (t1/2 = 2.0 x 10-4 s, ΔG‡ = 12.9 kcal/mol). Mechanistic studies show that this dramatic acid catalyzed change is due to stabilization of the planar transition state by the formation of an intramolecular hydrogen bond between the protonated quinoline nitrogen (N+-H) and an imide carbonyl (O=C). The acid catalyzed acceleration is reversible and can be stopped by addition of base.
Authors:
Brent E Dial; Perry J Pellechia; Mark D Smith; Ken Daniel Shimizu
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-2-9
Journal Detail:
Title:  Journal of the American Chemical Society     Volume:  -     ISSN:  1520-5126     ISO Abbreviation:  -     Publication Date:  2012 Feb 
Date Detail:
Created Date:  2012-2-10     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7503056     Medline TA:  J Am Chem Soc     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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