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Following the Azide‐Alkyne Cycloaddition at the Silica/Solvent Interface with Sum Frequency Generation
Author(s) -
Li Zhiguo,
Weeraman Champika N.,
GibbsDavis Julianne M.
Publication year - 2014
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201402161
Subject(s) - cycloaddition , azide , alkyne , chemistry , methanol , 1,3 dipolar cycloaddition , solvent , monolayer , photochemistry , catalysis , organic chemistry , biochemistry
The Cu I ‐catalyzed 1,3‐dipolar azide‐alkyne cycloaddition (CuAAC) has arisen as one of the most useful chemical transformations for introducing complexity onto surfaces and materials owing to its functional‐group tolerance and high yield. However, methods for monitoring such reactions in situ at the widely used silica/solvent interface are hampered by challenges associated with probing such buried interfaces. Using the surface‐specific technique broadband sum frequency generation (SFG), we monitored the reaction of a benzyl azide monolayer in real time at the silica/methanol interface. A strong peak at 2096 cm −1 assigned to the azides was observed for the first time by SFG. Using a cyano‐substituted alkyne, the decrease of the azide peak and the increase of the cyano peak (2234 cm −1 ) were probed simultaneously. From the kinetic analysis, the reaction order with respect to copper was determined to be 2.1, suggesting that CuAAC on the surface follows a similar mechanism as in solution.