This invention relates to a luminescent lanthanide chelate comprising a lanthanide
ion and a chelating ligand of formula (I)
##STR1##
wherein
R1 is selected from the group consisting H, —COOH,
—COO-, —CH2COOH and —CH2COO-;
G1 is a group consisting of one or two moieties each moiety being selected
from the group consisting of ethynediyl, ethenylene, phenylene, biphenylene, naphthylene,
pyridylene, pyrazinylene, pyrimidinylene, pyridazinylene, furylene, thienylene,
pyrrolylene, imidazolylene, pyrazolylene, thiazolylene, isothiazolylene, oxazolylene,
isoxazolylene, fyrazanylene, 1,2,4-triazol-3,5-ylene and oxadiazolylene; G2
for coupling to a biospecific binding reactant is selected from the group
consisting of amino, aminooxy, carbonyl, aldehyde or mercapto groups and activated
forms made of them; Z is selected from the group consisting of carboxyalkyl amine,
ether, thioether, carbonyl and unsubstituted or substitute methyl (—CR2—)
wherein group R2 is selected from the group consisting of H, methyl,
ethyl and carboxylalkyl; and the lanthanide ion is europium(III), terbium(III),
dysprosiym(III) or samarium(III). This invention further relates to a detectable
molecule comprising the lanthanide chelate and the use of the molecule in a method
of carrying out a biospecific binding assay.