Responsive luminescent lanthanide complexes

摘要

A compound of formula (I) is provided:; wherein: R¹ is an optionally substituted 2-(1-azathiaxanthone);each —R² is independently of the formula —CH₂—C(═O)—R⁴, wherein R⁴ is an amino acid or a salt thereof, attached to the remainder of R² through the nitrogen atom of the amino group; andR³ is hydrogen or a C_1-6 alkyl group; or wherein: R¹ is an optionally substituted 2-(1-azaxanthone);each R² is independently an optionally substituted glutaric or succinic acid, or a salt or ester thereof; andR³ is hydrogen or a C_1-6 alkyl group.