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Studies from Columbia University Have Provided New Data on Materials Science and Physical Chemistry (Adjusting the Surface Areal Density of...

July 11, 2014



Studies from Columbia University Have Provided New Data on Materials Science and Physical Chemistry (Adjusting the Surface Areal Density of Click-Reactive Azide Groups by Kinetic Control of the Azide Substitution Reaction on Bromine-Functional ...)

By a News Reporter-Staff News Editor at Science Letter -- Investigators discuss new findings in Science. According to news originating from New York City, New York, by NewsRx correspondents, research stated, "Azide-alkyne click chemistry has emerged as an important and versatile means for tethering a wide variety of guest molecules to virtually any substrate. In many of these applications, it is important to exercise control over the areal density of surface functional groups to achieve a desired areal density of the tethered guest molecule of interest."

Our news journalists obtained a quote from the research from Columbia University, "We demonstrate herein that the areal density of surface azide groups on flat germanium surfaces and nanoparticle substrates (silica and iron oxide) can be controlled kinetically by appropriately timed quenching of the S(N)2 substitution reaction of bromo-alkane-silane monolayers induced by the addition of sodium azide. The kinetics of the azide substitution reaction on monolayers formed on flat Ge substrates, determined by attenuated total reflection infrared spectroscopy (ATR-IR), are found to be identical to those for monolayers formed on both silica and iron oxide nanoparticles, the latter determined by transmission infrared spectroscopy. To validate the method, the percentages of surface bromine groups converted to azide groups after various reaction times were measured by quenching the S(N)2 reaction followed by analysis with ATR-IR (for Ge) and thermogravimetric analysis (after a subsequent click reaction with an alkyne-terminal polymer) for the nanoparticle substrates. The conversions found after quenching agree well with those expected from the standard kinetic curves. The latter result suggests that the kinetic method for the control of azide group areal density is a versatile means for functionalizing substrates with a prescribed areal density of azide groups for subsequent click reactions, and that the method is universal for any substrate, flat or nanoparticle, that can be modified with bromo-alkane-silane monolayers."

According to the news editors, the research concluded: "Regardless of the surface geometry, we find that the azide substitution reaction is complete within 2-3 h, in sharp contrast to previous reports that indicate times of 48-60 h required for completion of the reaction."

For more information on this research see: Adjusting the Surface Areal Density of Click-Reactive Azide Groups by Kinetic Control of the Azide Substitution Reaction on Bromine-Functional SAMs. Langmuir, 2014;30(21):6071-6078. Langmuir can be contacted at: Amer Chemical Soc, 1155 16TH St, NW, Washington, DC 20036, USA. (American Chemical Society - www.acs.org; Langmuir - www.pubs.acs.org/journal/langd5)

The news correspondents report that additional information may be obtained from S. Zhang, Columbia University, Dept. of Chem Engn, New York, NY 10027, United States. Additional authors for this research include Y. Maidenberg, K. Luo and J.T. Koberstein (see also Science).

Keywords for this news article include: Science, New York City, United States, North and Central America

Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC


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Source: Science Letter


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