Three novel aqueous soluble fulgimides, trifluoromethyl carboxylic acid indolylfulgimide 4, dicarboxylic acid indolylfulgimide 5, and carboxylic acid indolylfulgimide 6, were synthesized. Both 4 and 5 can switch back and forth between open and closed forms upon illumination with specific wavelengths of light, while 6 can only switch from the closed form to the open form. In sodium phosphate buffer (pH 7.4) at 37 °C, an unusual hydrolysis of the trifluoromethyl group of the closed form of 4 resulted in 5 which has an additional carboxylic acid group. The closed form of 5 was further decarboxylated to generate 6 which was not photochromic. In buffer, the open form of 4 degraded 20% after 10 days while the closed form of 4 was converted to 5 rapidly. In buffer, both leeswj@fiu.edu. Supporting Information Available: 1 H and 13 C NMR spectra of compounds 4, 5 and 6. This material is available free of charge via the Internet at