Metallopolymers of formula (I) where R.sup.1 and R.sup.1′; and R.sup.2 and R.sup.2′ are independently of each other, a C.sub.2-C.sub.10 alkyl group; X is CR3R3′ or NR4; R.sup.3 and R.sup.3′ are, independently of each other, as is R.sup.4, a C.sub.2-C.sub.10 alkyl group; L is a C.sub.4-C.sub.10 alkylene group; Ln.sup.1 and Ln.sup.2 are, independently of each other, chosen from the lanthanide cations; L.sup.1 and L.sup.2 are, independently of each other, chosen from the α-diketonate ligands; T is a neutral bidentate Lewis base including two coordinating nitrogen atoms; .fwdarw. represents a coordination of group T via the two nitrogen atoms of T to Ln.sup.1 and Ln.sup.2 respectively; Ln.sup.1 and Ln.sup.2 are, independently of each other, chosen from the lanthanide cations; L.sup.1 and L.sup.2 are, independently of each other, chosen from the β-diketonate, picolinate or dipicolinate monoanionic ligands; 0.01<x<0.50; 0<y<0.49, with x+y=0.50.

Photoluminescent and electroluminescent compositions are provided which comprise a matrix comprising aromatic repeat units and a luminescent metal ion or luminescent metal ion complex. Methods for producing such compositions, and the electroluminescent devices formed therefrom, are disclosed.