“…2a,3 To date several PRPGs have been developed to mask different functional groups including carboxylic acids, 4 alcohols, 5 amines, 6 phosphates, 7 aldehydes, 8 and ketones. 8 The carboxyl group containing molecules can be effectively protected by a variety of PRPGs, such as 2-(dimethylamino)-5-nitrophenol, 9 3-nitro-2-naphthalenemethanol, 10 a-carboxy nitrobenzyl, 11 p-hydroxyphenacyl, 12 a-keto amides, 13 1-acyl-nitroindolines, 14 anthracene-9-methanol, 15 and derivatives of quinoline 16 as well as coumarin. 17 Among the aforementioned PRPGs some groups are fluorescent and have greater advantage over non-fluorescent protecting groups since they not only release molecules of interest at desired location for a specific period of time, but also allow us to visualize, quantify and follow the spatial distribution, localization, and depletion of the released molecules.…”