Absorption spectra of a number of shellfish extracts have been obtained and reveal prominent absorptionsin all samples at 210 and 260 nm and at 325 nm in some of them. These absorptions preclude the useof chromophores with similar absorptions in testing of shellfish samples for paralytic shellfish toxins.Two crown ether chemosensors featuring a boron azadipyrrin chromophore have been synthesized; bothhave absorption maxima at 650 nm, where all the shellfish extracts are transparent. The synthetic sensorsfeature either 18- or 27-membered crown ether rings and have been evaluated as visible sensors for theparalytic shellfish toxin saxitoxin. The binding constant for one of them is in the range of 3-9 × 10
5M
-1 and exhibits a fluorescence enhancement of over 100% at 680 nm in the presence of 40
M saxitoxin.
