A luminescent lanthanide chelate comprising one or more chromophoric moieties of the formula or of the formula: wherein X is selected from -S-, -O-, -NR 1 -, -CR 1 R 2 -, >C=O, and >C=N-O-R 1 (an oxime of >C(=O)); wherein R 1 and R 2 each independently are selected from hydrogen, -(CH 2) 1-6 COOH, -(CH 2) 1-6 COO -, -(CH 2) 1-6 SO 3 H, -(CH 2) 1-6 SO 3 -, -(CH 2) 1-6 -O-PO 3 H 2, -(CH 2) 1-6 -O-PO 3 2-, -(CH 2) 1-6 PO 3 H 2, -(CH 2) 1-6 PO 3 2-, -(Ch 2) 1-6 NHR 5, -(CH 2) 1-6 NCH 3 R 5, -(Ch 2) 1-6 NEtR 5, -(Ch 2) 1-6 N(R 5) 2, -(CH 2) 1-6 N + (CH 3) 2 R 5, -(CH 2) 1-6 OH, - (CH 2 CH 2 O) 1-4 CH 2 CH 2 OH, -(CH 2 CH 2 O) 1-4 CH 2 CH 2 OCH 3, -(CH 2) 1-6 NHC(=O)R 5, -(CH 2) 1-6 NCH 3 C(=O)R 5, -(Ch 2) 1-6 C(=O)NHR 5, -(CH 2) 1-6 C(=O)NCH 3 R 5, -(CH 2) 1-6 C(=O)NEtR 5, -(CH 2) 1-6 C(=O)N(R 5) 2, -(CH 2) 1-6 NHC(=O)NHR 5, -(CH 2) 1-6 NHC(=S)NHR 5, -(Ch 2) 1-6 C(=O)R 5, -(Ch 2) 1-6 -C 6 H 4 -R 5, -COR 5, -CO(CH 2) 1-6 NHR 5, and -CO(CH 2) 1-6 NCH 3 R 5, wherein R 5 is selected from hydrogen, C 1-12 -alkyl (in particular C 1-6 -alkyl), -(CH 2) 1-6 COOH, -(CH 2) 1-6 COO -, -(Ch 2) 1-6 SO 3 H, -(CH 2) 1-6 SO 3 -, -(CH 2) 1-6 N + (CH 3) 2 (CH 2) 1-6 SO 3 -, -(CH 2) 1-6 -O-PO 3 H 2, -(CH 2) 1-6 -O-PO 3 2-, -(CH 2) 1-6 PO 3 H 2, -(CH 2) 1-6 PO 3 2-, a hydrophilic group (optionally including a spacer), a reactive group (optionally including a spacer), an oligopeptide, a polypeptide and a nucleotide; R 3 and R 4 each represent a bond between the chromophoric moiety and other moieties of the chelate, R 6 is selected from hydrogen -Cl, -Br, -F, -I, -CH 3, -(CH 2) 1-6 OH, -(CH 2) 1-6 OCH 3 -CF 3,-CN, -NO 2, -OH, -OCH 3, -O(CH 2) 1-6 OH, -O(CH 2) 1-6 OCH 2, -O(CH 2) 1-6 COOH, -O(CH 2) 1-6 COO -, -SCH 3, -S(CH 2) 1-6 OH, -S(CH 2) 1-6 OCH 2, -S(CH 2) 1-6 COOH, -S(CH 2) 1-6 COO -, -CONH 2, -CONHCH 3, -CON(CH 3) 2, -CONH(CH 2) 1-6 OH, -CONHCH(CH 2 OH) 2,-CONHC(CH 2 OH) 3, -NHCOCH 3, -NHCO(CH 2) 1-6 OH, -NHCO(CH 2) 1-6 COOH, -NHCO(CH 2) 1-6 COO -, a reactive group Z, and a hydrophilic group; and Ln 3+ is a lanthanide ion. wherein X is selected from -S-, -O-, -NR 1 -, -CR 1 R 2 -, >C=O, and >C=N-O-R 1 (an oxime of >C(=O)); wherein R 1 and R 2 each independently are selected from hydrogen, -(CH 2) 1-6 COOH, -(CH 2) 1-6 COO -, -(CH 2) 1-6 SO 3 H, -(CH 2) 1-6 SO 3 -, -(CH 2) 1-6 -O-PO 3 H 2, -(CH 2) 1-6 -O-PO 3 2-, -(CH 2) 1-6 PO 3 H 2, -(CH 2) 1-6 PO 3 2-, -(Ch 2) 1-6 NHR 5, -(CH 2) 1-6 NCH 3 R 5, -(Ch 2) 1-6 NEtR 5, -(Ch 2) 1-6 N(R 5) 2, -(CH 2) 1-6 N + (CH 3) 2 R 5, -(CH 2) 1-6 OH, - (CH 2 CH 2 O) 1-4 CH 2 CH 2 OH, -(CH 2 CH 2 O) 1-4 CH 2 CH 2 OCH 3, -(CH 2) 1-6 NHC(=O)R 5, -(CH 2) 1-6 NCH 3 C(=O)R 5, -(Ch 2) 1-6 C(=O)NHR 5, -(CH 2) 1-6 C(=O)NCH 3 R 5, -(CH 2) 1-6 C(=O)NEtR 5, -(CH 2) 1-6 C(=O)N(R 5) 2, -(CH 2) 1-6 NHC(=O)NHR 5, -(CH 2) 1-6 NHC(=S)NHR 5, -(Ch 2) 1-6 C(=O)R 5, -(Ch 2) 1-6 -C 6 H 4 -R 5, -COR 5, -CO(CH 2) 1-6 NHR 5, and -CO(CH 2) 1-6 NCH 3 R 5, wherein R 5 is selected from hydrogen, C 1-12 -alkyl (in particular C 1-6 -alkyl), -(CH 2) 1-6 COOH, -(CH 2) 1-6 COO -, -(Ch 2) 1-6 SO 3 H, -(CH 2) 1-6 SO 3 -, -(CH 2) 1-6 N + (CH 3) 2 (CH 2) 1-6 SO 3 -, -(CH 2) 1-6 -O-PO 3 H 2, -(CH 2) 1-6 -O-PO 3 2-, -(CH 2) 1-6 PO 3 H 2, -(CH 2) 1-6 PO 3 2-, a hydrophilic group (optionally including a spacer), a reactive group (optionally including a spacer), an oligopeptide, a polypeptide and a nucleotide; R 3 and R 4 each represent a bond between the chromophoric moiety and other moieties of the chelate, R 6 is selected from hydrogen -Cl, -Br, -F, -I, -CH 3, -(CH 2) 1-6 OH, -(CH 2) 1-6 OCH 3 -CF 3,-CN, -NO 2, -OH, -OCH 3, -O(CH 2) 1-6 OH, -O(CH 2) 1-6 OCH 2, -O(CH 2) 1-6 COOH, -O(CH 2) 1-6 COO -, -SCH 3, -S(CH 2) 1-6 OH, -S(CH 2) 1-6 OCH 2, -S(CH 2) 1-6 COOH, -S(CH 2) 1-6 COO -, -CONH 2, -CONHCH 3, -CON(CH 3) 2, -CONH(CH 2) 1-6 OH, -CONHCH(CH 2 OH) 2,-CONHC(CH 2 OH) 3, -NHCOCH 3, -NHCO(CH 2) 1-6 OH, -NHCO(CH 2) 1-6 COOH, -NHCO(CH 2) 1-6 COO -, a reactive group Z, and a hydrophilic group; and Ln 3+ is a lanthanide ion.