Synthesis and characterization of fluorinated derivatives of cresolsulfonphthalein

The reaction between dilute fluorine gas and cresolsulfonphthalein in acetic acid was investigated. The mono-, di-, and trifluorinated cresolsulfonphthalein derivatives were isolated and characterized. These compounds possessed the properties of pH indicators with biologically relevant pK(a) values (6.4-7.5) and the absorption maxima of the basic forms at 582-592 nm. This method can be used for synthesis of positron-emitting F-18-labeled pH indicators with potential application for non-invasive in vivo pH measurement in biological objects. (C) 2012 Elsevier B.V. All rights reserved.