Thiol-reactive luminescent lanthanide chelates: part 2.

Luminescent lanthanide complexes have unusual spectroscopic characteristics, including millisecond excited-state lifetime and sharply spiked emission spectra. These characteristics make them valuable alternatives to conventional organic fluorescent probes in detection applications and for measuring nanometer-scale conformational changes in biomolecules via resonance energy transfer. Our group has previously reported the syntheses and application of various luminescence complexes that have polyaminocarboxylate chelates coupled to a carbostyril antenna and thiol or amine-reactive groups. Here we report the syntheses of new thiol-reactive forms of DTPA-cs124 chelates, including two iodoacetamide forms (phenylalanine-iodoacetamide and ethylenediamine iodoacetamide) and two methane-thio-sulfonate forms (ethylmethanethiosulfonate and carboxyethylmethanethiosulfonate). In addition, we have developed an improved synthesis of a previously reported maleimide form.