The chemical reactions in electrosprays of water do not always correspond to those at the pristine air–water interface

by Gallo Adair, Andreia SF Farinha, Miguel Dinis, Abdul-Hamid Emwas, Adriano Santana, Robert J. Nielsen, William A. Goddard, And Himanshu Mishra
Year: 2019

Bibliography

The chemical reactions in electrosprays of water do not always correspond to those at the pristine air–water interface.
Gallo, A., Farinha, A.S., Dinis, M., Emwas, A.H., Santana, A., Nielsen, R.J., Goddard, W.A. and Mishra, H., Chemical Science, 2019, Advance Article, DOI: 10.1039/C8SC05538F

Abstract

The recent application of electrosprays to characterize the air–water interface, along with the reports on dramatically accelerated chemical reactions in aqueous electrosprays, have sparked a broad interest. Herein, we report on complementary laboratory and in silico experiments tracking the oligomerization of isoprene, an important biogenic gas, in electrosprays and isoprene–water emulsions to differentiate the contributions of interfacial effects from those of high voltages leading to charge-separation and concentration of reactants in the electrosprays. To this end, we employed electrospray ionization mass spectrometry, proton nuclear magnetic resonance, ab initio calculations and molecular dynamics simulations. We found that the oligomerization of isoprene in aqueous electrosprays involved minimally hydrated and highly reactive hydronium ions. Those conditions, however, are non-existent at pristine air–water interfaces and oil–water emulsions under normal temperature and pressure. Thus, electrosprays should be complemented with surface-specific platforms and theoretical methods to reliably investigate chemistries at the pristine air–water interface.

Keywords

air-water interface aqueous electrosprays isoprene