Using Heck reaction to sense transition metals via catalytic signal amplification

ORGN 714

Qiaoyin Wu and Eric V. Anslyn. Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, TX 78712
Catalytic signal enhancement using Heck cross coupling is demonstrated. The reactivity of a Heck reaction that creates a fluorophore is modulated by the addition of an inhibitor which will poison catalyst. When an analyte with high affinity is present in the system, the inhibitor preferentially complexes with the analyte thus restoring the activity of the Pd(II). The addition of analyte therefore leads to the generation of fluorescence, thereby creating a very sensitive assay for analyte-Cu (II) or Cd(II). The rate of the Heck reaction is calculated by monitoring the emission of fluorophore as a function of time. The rate is proportional to the analyte concentration, and correlates to the affinity of the inhibitor to various metals. This strategy represents a general technique that can be exploited to other catalytic organometallic reactions.