| abstract |
A complex comprises a multidentate ligand that is coordinated to a lanthanide ion selected from europium and terbium, and the multidentate ligand has (i) at least one optionally substituted phthalimide group coordinated to the lanthanide ion or (ii) at least one optionally substituted phthalamate group coordinated to the lanthanide ion. A method of changing the fluorescent properties of the complex (i) comprises contacting the complex with an aqueous liquid medium such that at least one phthalimide group is hydrolysed to a phthalamate group (i.e. complex (i) may be converted to complex (ii) on exposure to base; complex (i) may serve as a pH sensor). Macrocyclic compounds of formula (I) (as further defined in claims 18, 20 and 21: for example L1, L2, L3, L4 are each selected from -(CR5R5)n-; n is 2 or 3; one or more of R1-R4 may be a linker-phthalimide moiety) are also described. The macrocyclic compound may be 1,4-bis-(N-[phthalimide]propyl)-7,10-triacetic acid-1,4,7,10- tetraazacyclododecane. (I) |