Near-infrared luminescent materials: From β-diketonate ytterbium complexes to β-diketonate-ytterbium-complex@PMMA thin film

In view of the potential application of NIR luminescence in biology, a series of four new 3,5-Heptanedione (β-diketonate) ytterbium complexes, e.g. [Yb(L) 3 (H 2 O) 2 ] ( 1 ), [Yb(L) 3 (2,2′-bpy)] ( 2 ), [Yb(L) 3 (dpq)] ( 3 ) and [Yb(L) 3 (dppz)] ( 4 ) have been designed and isolated. Crystal structures analysis show that all complexes 1 – 4 exhibit the similar mononuclear structure, in which the central Yb 3+ ion is eight-coordinated forming the square-anti-prismatic geometry. NIR luminescence of all complexes 1 – 4 shows strong characteristic emission of Yb 3+ ions. To improve the mechanical and thermal stability, complex 1 was further doped into poly-(methyl methacrylate) (PMMA) for preparing a thin film ( 1 @PMMA). Their thermal stability and NIR luminescence were essentially enhanced in contrast to that for complex 1 . This NIR luminescent thin film may be of potential applications in biological dictation and luminescent probe.