We present a simple, two- or three-step method for the synthesis of chromogenic octamethylcalixpyrrole-based (OMCP) sensors for anions. Electrophilic aromatic substitution allows for converting the pyrrole moieties of OMCP into a dye. The formation of a sensor-anion complex results in partial charge transfer and a dramatic change in color. The absorption (UV-vis) and NMR titration experiments show that the chromogenic OMCPs sense anions administered as aqueous solutions, even at high ionic strength ( approximately 0.1 M NaCl), while displaying selectivity for pyrophosphate and carboxylate anions. The experiments with polyurethane sensor films show a strong response for aqueous carboxylates, such as antipyretics naproxen approximately ibuprofen > salicylate, without being biased by bicarbonate or carboxy termini of blood plasma proteins.
Nishiyabu, Ryuhei and Anzenbacher, Pavel Jr., "Sensing Of Antipyretic Carboxylates By Simple Chromogenic Calixpyrroles" (2005). Chemistry Faculty Publications. 91.
Journal Of The American Chemical Society