PMMA-supported hybrid materials doped with highly near-infrared (NIR) luminescent complexes [Zn(L1)(Py)Ln(L2)3] (Ln = Nd, Yb or Er)

Abstract

Through the self-assembly of a precusor [Zn(L¹)(Py)] based on the typical Salen-type Schiff-base ligand H₂L¹ (H₂L¹ = N,N′-bis(salicylidene)cyclohexane-1,2-diamine, Py = pyridine), a trifluorinated and acylpyrazole-modified β-diketonate ligand HL² (HL² = (Z)-3-methyl-1-phenyl-4-(2,2,2-trifluoro-1-hydroxyethylidene)-1H-pyrazol-5(4H)-one) and LnCl₃·6H₂O (Ln = La, Nd, Yb, Er or Gd), a series of tris-β-diketonate hetero-binuclear complexes [Zn(L¹)(Py)Ln(L²)₃] (Ln = La, 1; Ln = Nd, 2; Ln = Yb, 3; Ln = Er, 4 or Ln = Gd, 5) were obtained. Notably, complexes 2–4, with good NIR luminescent properties, were doped into PMMA (poly(methyl methacrylate)) matrices, giving the series of PMMA-supported doping hybrid materials PMMA@[Zn(L¹)(Py)Ln(L²)₃], where the doping not only results in improved thermal stability and film-forming property, but also endows more efficient NIR luminescence even at a doping concentration of up to 100 : 1.