Compounds useful as ligands and particularly as organic chromophores for complexing lanthanides and applications thereof

A process for complexing a lanthanide with an organic chromophore, comprising putting the lanthanide in contact with the organic chromophore to form a complex, the organic chromophore being a compound of formula (II):

• wherein:
• either a group of formula:
• wherein:
• R1 is (a) a hydrogen atom;
• (b) a halogen atom;
• (c) a 5-membered aromatic ring or a 6-membered aromatic ring, the ring comprising one or more heteroatoms or one or more non-cyclic substituents;
• (d) a sequence of at least two 5-membered aromatic rings or a sequence of at least two 6-membered aromatic rings, the rings being bonded to one another by a covalent bond and at least one of the rings optionally comprising one or more heteroatoms or one or more non-cyclic substituents;
• or (e) a linear or branched C1 to C12 hydrocarbon group optionally comprising one or more heteroatoms;
• and
• R2 is (a) a carboxylic acid group;
• (b) a 5-membered aromatic ring or a 6-membered aromatic ring, the ring optionally comprising one or more heteroatoms or one or more non-cyclic cyclic substituents;
• or (c) a 2-(1H-tetrazol-5-yl)pyridine unit;
• or Y is (a) a non-aromatic ring optionally comprising one or more heteroatoms or one or more substituents;
• or (b) a group —(CH2)p—Z where p is an integer from 1 to 6 and Z is a non-aromatic ring, optionally comprising one or more heteroatoms or one or more substituents;
• whereby the lanthanide is complexed with the organic chromophore.