Red Luminescent Eu(III) Coordination Bricks Excited on Blue LED Chip

Three types of red luminescent Eu(III) complexes with Schiff base and hfa ligands (hfa: hexafluoroacetylacetonate), mononuclear [Eu(hfa)(2)(OAc)(salen)(2)] (OAc: acetate anion, salen: N,N'-bis(salicylidene)ethylenediamine), brick-type [Eu-2(hfa)(4)(OAc)(2)(salbn)(2)] (salbn: N,N'-bis(salicylidene)-1,4-butanediamine), and polynuclear [Eu(hfa)(2)(OAc)(salhen)]n (salhen: N,N'-bis(salicylidene)-1,6-hexanediamine) are reported for white light-emitting diode (LED) devices. Among these complexes, brick-type [Eu-2(hfa)(4)(OAc)(2)(salbn)(2)] excited by blue light (460 nm) exhibits the photosensitized quantum yield (Phi(pi-pi*) = 47%) and remarkably high efficiency of sensitization (eta(sens) = 96%). The efficiency of sensitization is caused by the excited state based on ligand-ligand interaction between the Schiff base and hfa ligands in Eu(III) complexes. To fabricate LED devices, the red luminescent [Eu-2(hfa)(4)(OAc)(2)(salbn)(2)] was mounted on an InGaN blue LED chip.