Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published September 27, 2000 | metadata_only
Journal Article

Chemistry in Nanodroplets: Studies of Protonation Sites of Substituted Anilines in Water Clusters Using FT-ICR


Water clusters of protonated substituted anilines generated by an electrospray ion source have been investigated using a Fourier Transform ion cyclotron resonance mass spectrometer. It is observed that evaporation kinetics and cluster distributions are highly dependent on sites of protonation in the substituted anilines. Based on the examination of the water cluster distributions of protonated aniline derivatives, the site of protonation is postulated to be the amine group for aniline, p-anisidine, p-thiomethylaniline, p-ethylaniline, and m-ethylaniline. The water cluster distributions of these compounds display magic number clusters ([M + nH_2O]+) for n = 20, 27, 50, and 52. However, there is no indication of clusters with special stability for m-anisidine and m-thiomethylaniline, suggesting that these compounds protonate on the ring. DFT calculations have been performed to obtain proton affinities for the different sites of protonation in the substituted anilines and are in good agreement with experimental observation.

Additional Information

© 2000 American Chemical Society. Received 20 March 2000. Published online 8 September 2000. Published in print 1 September 2000. The authors are grateful to Dr. Yun Hee Chang for helpful discussions. This work was supported in part by the National Science Foundation under Grant CHE-9727566. Funds for instrument development have been provided by ARPA and the DOD-URI program (ONR-N0014-92-J-1901). H.C. gratefully acknowledges the support of a National Science Foundation graduate research fellowship. We are also indebted to the Beckman Foundation and Institute for the initial funding and continuing support of the research facilities. Computing resources were generously provided by the Material and Process Simulation Center (MSC), also part of the Beckman Institute.

Additional details

August 19, 2023
August 19, 2023