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excited the chiral chemistry community by showing that DNA microarray technology could be adapted to ee measurement. With the new technology, called reaction microarrays, picoliter amounts of a mixture are spotted onto a glass surface and then made to react with fluorescent chiral probes. When a spot is excited by laser, the fluorophores of the chiral probe emit with intensities proportional to the ee at that spot. Spots can be applied at densities of up to 100,000 per 3-sq-in glass slide, making for very high-throughput ee measurements. Author have been optimizing the reaction microarray system. Currently, they are developing a general way to attach molecules to a glass surface through the carbon-hydrogen insertion chemistry of nitrenes. "Every molecule we care about would have a C–H bond. "If you could come up with a chemistry that attached any compound irrespective of the structure, you could use reaction microarrays for almost any reaction product, as long as that molecule also had some handle to which a chiral probe can be attached." Nitrenes are species in which a nitrogen atom bears two unpaired electrons. To generate nitrenes, author coats the glass slide with an azide and then irradiates the slide with a handheld ultraviolet lamp. "What we believe happens is that N2 is removed photochemically from the azide, leaving a nitrene." In principle, the nitrene would insert into enantiomers of a mixture whose ee is to be determined. Preliminary results are promising, but author says it's difficult to know for sure what's going on. "It's hard to find out what you've done on a glass surface," he explains. "That has slowed our progress." Still, author is optimistic that his lab can soon use reaction microarrays to screen a new catalytic aldol reaction that he and his coworkers have been developing
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