Homoleptic imidazolate frameworks (3)(infinity)[Sr1-xEux(Im)(2)]-hybrid materials with efficient and tuneable luminescence

Homoleptic frameworks of the formula (3)(infinity)[Sr1-xEux(Im)(2)] (1) (x = 0.01-1.0; Im(-) = imidazolate anion, C3H3N2-) are hybrid materials that exhibit an intensive green luminescence. Tuning of both emission wavelength and quantum yield is achieved by europium/strontium substitution so that a QE of 80% is reached at a Eu content of 5%. Even 100% pure europium imidazolate still shows 60% absolute quantum efficiency. Substitution of Sr/Eu shows that doping with metal cations can also be utilized for coordination compounds to optimize materials properties. The emission is finely tuneable in the region 495-508 nm via variation of the europium content. The series of frameworks (3)(infinity)[Sr1-xEux(Im)(2)] presents dense MOFs with the highest quantum yields reported for MOFs so far.