A new example of an exponential signal amplification strategy for the direct detection of fluoride is demonstrated. The amplification occurred through reaction of fluoride with a responsive chromogenic probe. The probe activity is based on a unique dendritic chain reaction that generates a fluoride anion, which is the analyte of interest, during the disassembly pathway of the dendritic probe. This autoinductive amplification mechanism may be applied for detection of other analytes by coupling activity of a modified probe with that of the fluoride amplifier.

The quinone-methide elimination is a common, efficient methodology used in linkers designed to undergo self-fragmentation. Here, for the first time, we demonstrate this elimination in a pyridine ring system. Under physiological conditions, a compound constructed of a pyridine core, a reporter, and an enzymatic trigger underwent significantly faster 1,4-elimination than its parent compound with a benzene core. In addition, an AB(2) self-immolative dendron based on a pyridine core released its two reporter units upon activation through 1,6- and 1,4 pyridinone-methide elimination reactions, again faster than the analogous benzene system. Increased aqueous solubility was observed with compounds based on pyridine relative to those based on benzene. The pyridinone-methide elimination could be applied as an alternative tool in designing self-immolative linkers for release of active target molecules in an aqueous environment.