A rational approach to the formation of pure heteropolymetallic lanthanide complexes that uses a two-step assem
blystrate
gy and exploits the different size requirements of the two metals included in the final structure is descri
bed.The investi
gation of the assem
bly of [LnL
2](Otf) (L = 2,2':6',2' '-terpyridine-6-car
boxylate) complexes into hexametallicrin
gs hostin
g an additional hexacoordinated lanthanide cation was crucial for the development of this strate
gy. Theformation and size of the cyclic assem
bly are controlled
by the ionic radius and
by the coordination num
ber of thelanthanides. The rather hi
gh luminescence quantum yield of the heptaeuropium complex (25%) indicates that therin
g structure is well adapted to include hi
ghly luminescent lanthanide complexes in nanosized architecture. Theuse of a stepwise synthetic strate
gy leads to the selective assem
bly of lar
ge heteropolymetallic rin
gs. The additionof a smaller lanthanide ion to the [EuL
2](Otf) complex in anhydrous acetonitrile leads selectively to heterometallicspecies with the Eu ions located on the peripheral sites and the smaller ion occupyin
g only the central site. Thehi
gh selectivity is the result of the different size requirements of the two metal sites present in the cyclic structure.The heterometallic structure of the isolated [Lu
![](/ima<font color=)
ges/entities/su
b.
gif">(EuL
2)
6](Otf)
9 complex was confirmed
by X-ray diffraction and
byhi
gh resolution solid-state photophysical studies. The descri
bed synthetic approach allowed us to o
btain the firstexample of selective assem
bly of two different lanthanide ions in a lar
ge polymetallic structure characterized insolution and in the solid state and will make the isolation of planned dimetallic com
binations presentin
g differentlanthanide emitters in the peripheral sites possi
ble.