The first example of Tb3-containing metallopolymer-type hybrid materials with efficient and high color-purity green luminescence

Abstract

In the series of homo-leptic trinuclear complexes {[Ln₃(L)₄Cl₄(MeOH)(H₂O)]·Cl} (Ln = La, 1; Ln = Eu, 2; Ln = Tb, 3 or Ln = Gd, 4) self-assembled from the allyl-modified benzimidazole-type ligand HL (4-allyl-2-(1H-benzo[d]imidazol-2-yl)-6-methoxyphenol) and LnCl₃·6H₂O, a suitable energy level match endows efficient green luminescence (Φ_overall = 72%) of Tb₃-arrayed complex 3. The copolymerization between each of these complex monomers 1–4 and CC-containing MMA (methyl methacrylate) or NBE (norbornene) shows that degradative chain transfer of the terminal four flexible allyl groups within restrains their radical polymerization with MMA while it does not hinder their effective ring-opening metathesis polymerization (ROMP) with NBE. Thus, two kinds of PMMA-supported doping hybrid materials 1@PMMA, 2@PMMA, 3@PMMA and 4@PMMA and PNBE-supported metallopolymer-type hybrid materials Poly(NBE-1), Poly(NBE-2), Poly(NBE-3) and Poly(NBE-4) are obtained, respectively. Especially for both 3@PMMA and Poly(NBE-3) with high color-purity characteristic green emission of Tb³⁺ ions, improved physical properties including significantly enhanced luminescence (Φ_overall = 76% or 83%) are observed, and covalent-bonding endows a higher-concentration self-quenching as compared to physical doping.