Shunsheng Zhao

Hetero-trinuclear near-infrared (NIR) luminescent Zn2Ln complexes from Salen-type Schiff-base ligands

With the Zn–Schiff-base [ZnL11(Py)] or [ZnL22(Py)] from the simple Salen-type Schiff-base ligand H22L11 or H22L22 (H22L11: N,N′-bis(salicylidene)ethylene-1,2-diamine; H22L22: N,N′-bis(salicylidene)phenylene-1,2-diamine) without the outer O2O2 portion as the precursor, two series of eight trinuclear Zn2Ln arrayed complexes (Ln = Nd (1 or 5), Yb (2 or 6), Er (3 or 7) or Gd (4 or 8)) have been obtained by the further reaction with Ln(NO3)3·6H2O, respectively. The results of photophysical studies show that the strong and characteristic NIR luminescence with emissive lifetimes in microsecond ranges, has been sensitized from the excited state (1LC and 3LC or only 1LC) of the ligand, whereas the Zn(II)-based visible luminescence is mostly quenched because of quite effective intramolecular energy transfer from the ligand-centered excited state of the Zn(II)–Schiff base complex to Ln(III) ions.

Synthesis, Characterization, and Photophysical Properties of First Heterobinuclear Zn-Ln (Ln = La, Nd, Eu, Gd, Tb, Er, and Yb) Complexes Based on Asymmetric Schiff-Base Ligand

ABSTRACT With a novel asymmetric Schiff-base zinc complex ZnL(H 2 L = N-(3-methoxysalicylidene)-N’-(5-(4-cyanophenyl)-3-methoxysalicylidene)phenylene-1, 2-diamine), obtained from phenylene-1, 2-diamine, 3-methoxysalicylaldehyde, and 5-(4-cyanophenyl)-3-methoxysalicylaldehyde, as the precursor, a series of heterobinuclear Zn-Ln complexes [ZnLnL(NO 3 ) 3 (CH 3 CN)] (Ln = La, 1; Ln = Nd, 2; Ln = Eu, 3; Ln = Gd, 4; Ln = Tb, 5; Ln = Er, 6; Ln = Yb, 7) were obtained by further reaction with Ln(NO3)3 · 6H2O. Photophysical studies of these complexes show that the strong and characteristic NIR luminescence with emissive lifetimes in the microsecond range has been sensitized from the excited state of the asymmetric Schiff-base ligand due to effective intramolecular energy transfer.

CCDC 861935: Experimental Crystal Structure Determination

Related Article: Shunsheng Zhao, Xiangrong Liu, Wai-Yeung Wong, Xingqiang Lu, Wai-Kwok Wong|2014|Inorg.Chim.Acta|41|160|doi:10.1016/j.ica.2014.02.003