title: Near-infrared (NIR) luminescent hetero-tetranuclear Zn2Ln2 (Ln = Nd, Yb or Er) complexes self-assembled from the benzimidazole-based HL and two rigid 4,4'-bipyridine ligands with different spacers.
abstract: Through the self-assembly of the benzimidazole-based ligand HL (HL=2-(1H-benzo[d]imidazol-2-yl)-6-methoxyphenol) with Zn(OAc)2 · 2H2O, Ln(NO3)3·6H2O (Ln=Nd, Yb, Er or Gd) and 4,4'-bipyridine ligand (bpy, 4,4'-bipyridine or bpe, trans-bis(4-pyridyl)ethylene), two series of Zn2Ln2-arrayed complexes [Zn(2)Ln(2)(L)4(bpy)(NO3)6] (Ln=Nd, 1; Yb, 2; Er, 3 or Gd, 4) and [Zn(2)Ln(2)(L)4(bpe)(NO3)6] (Ln=Nd, 5; Yb, 6; Er, 7 or Gd, 8) were obtained, respectively. The result of their photophysical properties shows that the characteristic near-infrared (NIR) luminescence of Nd(3+), Yb(3+) or Er(3+) ion has been sensitized from the excited state (both (1)LC and (3)LC) of the mixed HL and bipyridyl ligands in both complexes 1-3 and 5-7. Moreover, the change from bpy to bpe bridging for the fine-tuning of whole molecular conjugations, attributing to the different crossings of the two benzimidazole-based L(-) ligands, has the important influence on their NIR luminescent properties.
authors.affiliation: Shaanxi Key Laboratory of Degradable Medical Material, Shaanxi Key Laboratory of Physico-inorganic Chemistry, Northwest University, Xi'an 710069, Shaanxi, China.
authors.forename: Zhao
authors.initials: Z
authors.lastname: Zhang
authors.forename: Weixu
authors.initials: W
authors.lastname: Feng
authors.forename: Peiyang
authors.initials: P
authors.lastname: Su
authors.forename: Han
authors.initials: H
authors.lastname: Liu
authors.forename: Yao
authors.initials: Y
authors.lastname: Zhang
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wang
authors.forename: Tiezheng
authors.initials: T
authors.lastname: Miao
authors.forename: Xingqiang
authors.initials: X
authors.lastname: Lü
authors.forename: Daidi
authors.initials: D
authors.lastname: Fan
authors.forename: Wai-Kwok
authors.initials: WK
authors.lastname: Wong
authors.forename: Richard A
authors.initials: RA
authors.lastname: Jones
mesh_terms: D001562:Benzimidazoles / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D008024:Ligands; D049449:Luminescence; D049408:Luminescent Agents / Q000737:chemistry*; D008958:Models, Molecular; D011725:Pyridines / Q000737:chemistry*
chemical_list: D001562:Benzimidazoles; D056831:Coordination Complexes; D028581:Lanthanoid Series Elements; D008024:Ligands; D049408:Luminescent Agents; D011725:Pyridines; C031000:benzimidazole; C034306:4,4'-bipyridyl
keywords: Hetero-tetranuclear Zn(2)Ln(2)-arrayed complexes; Mixed HL-bipyridine ligands; Sensitization of NIR luminescence