Attenuated total reflection-infrared nanofluidic chip with 71 nL detection volume for in situ spectroscopic analysis of chemical reaction intermediates

Analytical Chemistry
Engin KarabudakHan J G E Gardeniers

Abstract

We present a micromachined silicon attenuated total reflection-infrared (ATR-IR) crystal with integrated nanofluidic glass channels which enables infrared spectroscopic studies with only 71 nL sample volume. Because of the short path length through silicon, the system allows IR spectroscopy down to 1200 cm(-1), which covers the typical fingerprint region of most organic compounds. To demonstrate proof-of-principle, the chip was used to study a Knoevenagel condensation reaction between malononitrile and p-anisaldehyde catalyzed by different concentrations of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in solvent acetonitrile. By in situ measurement, it was demonstrated for the first time that at certain concentrations of DBU, reaction intermediates become stabilized, an effect that slows down or even stops the reaction. This is thought to be caused by increased ionic character of the solvent, in which protonated DBU stabilizes the intermediates. This clearly demonstrates that infrared mechanistic studies of chemical reactions are feasible in volumes as little as 71 nL.

References

Aug 23, 2003·Chemical Communications : Chem Comm·Monica BrivioDavid N Reinhoudt
Nov 2, 2004·Analytical Chemistry·Rachel Herzig-MarxKlavs F Jensen
May 12, 2005·Nano Letters·Rohit KarnikArun Majumdar
Jun 18, 2005·The Journal of Organic Chemistry·David J HeldebrantCharles L Liotta
Nov 22, 2007·Lab on a Chip·Wojciech P BulaHan J G E Gardeniers
Oct 31, 2008·Talanta·C ViganoErik Goormaghtigh
Feb 24, 2009·Analytical and Bioanalytical Chemistry·Han J G E Gardeniers
Feb 25, 2010·Chemical Society Reviews·Takehiko TsukaharaTakehiko Kitamori
Feb 24, 2011·Journal of the American Chemical Society·Sergey MozharovJohn M Girkin
May 24, 2011·Analytical Chemistry·Evan T OgburnWilliam R Heineman

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Citations

Apr 2, 2015·Lab on a Chip·Zhaoyi WangEugenia Kumacheva
Jul 12, 2012·Physical Chemistry Chemical Physics : PCCP·Engin KarabudakHan J G E Gardeniers
Oct 12, 2017·Analytical Chemistry·Tyler A MorhartIan J Burgess
Mar 12, 2020·Analytical Chemistry·Bettina BaumgartnerBernhard Lendl

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