title: Temperature-dependent self-assembly of near-infrared (NIR) luminescent Zn2Ln and Zn2Ln3 (Ln=Nd, Yb or Er) complexes from the flexible Salen-type Schiff-base ligand.
abstract: Through the self-assembly of the precursor [Zn(L)(MeCN)] (H2L=N,N'-bis(3-methoxy-salicylidene)cyclohexane-1,2-diamine) with LnCl3·6H2O (Ln=La, Nd, Yb, Er or Gd) and NaN3 in alcohol-containing solutions, two series of mixed anions-induced Zn2Ln-arrayed complexes [Zn2(L)2(MeOH)ClLn(N3)]·Cl (Ln=La, 1; Ln=Nd, 2; Ln=Yb, 3; Ln=Er, 4 or Ln=Gd, 5) and Zn2Ln3-arrayed complexes [Zn2(L)3Cl2(μ2-OH)(μ3-OH)2Ln3(N3)2] (Ln=La, 6; Ln=Nd, 7; Ln=Yb, 8; Ln=Er, 9 or Ln=Gd, 10) are obtained at room temperature or under reflux, respectively. In contrast to Zn2Ln-arrayed complexes with the two Zn2+ ions in the inner cis-N2O2 cores and one Ln3+ ion in the outer O2O2 moieties, the demetalation of partial precursors leads to the selective exchange of Zn2+ centers for the Ln3+ ions for the formation of novel heterometallic Zn2Ln3-arrayed complexes with the Ln3+ ions in both the inner cis-N2O2 core and the outer O2O2 moieties of the ligands. The result of their photophysical properties shows that the characteristic near-infrared (NIR) luminescence of Nd3+ or Yb3+ ion has been sensitized from the excited state (both 1LC and 3LC) of the ligand H2L, while relatively lower quantum yields for Zn2Ln3-arrayed complexes than those for Zn2Ln-arrayed complexes, correspondingly, should be due to the luminescent quenching with the involvement of OH- oscillators around the Ln3+ ions.
authors.affiliation: School of Chemical Engineering, Shaanxi Key Laboratory of Degradable Medical Material, Northwest University, Xi'an 710069, Shaanxi, China.
authors.forename: Tiezheng
authors.initials: T
authors.lastname: Miao
authors.affiliation: School of Chemical Engineering, Shaanxi Key Laboratory of Degradable Medical Material, Northwest University, Xi'an 710069, Shaanxi, China.
authors.forename: Zhao
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: School of Chemical Engineering, Shaanxi Key Laboratory of Degradable Medical Material, Northwest University, Xi'an 710069, Shaanxi, China.
authors.forename: Weixu
authors.initials: W
authors.lastname: Feng
authors.affiliation: School of Chemical Engineering, Shaanxi Key Laboratory of Degradable Medical Material, Northwest University, Xi'an 710069, Shaanxi, China.
authors.forename: Peiyang
authors.initials: P
authors.lastname: Su
authors.affiliation: School of Chemical Engineering, Shaanxi Key Laboratory of Degradable Medical Material, Northwest University, Xi'an 710069, Shaanxi, China.
authors.forename: Heini
authors.initials: H
authors.lastname: Feng
authors.affiliation: School of Chemical Engineering, Shaanxi Key Laboratory of Degradable Medical Material, Northwest University, Xi'an 710069, Shaanxi, China. Electronic address: lvxq@nwu.edu.cn.
authors.forename: Xingqiang
authors.initials: X
authors.lastname: Lü
authors.affiliation: School of Chemical Engineering, Shaanxi Key Laboratory of Degradable Medical Material, Northwest University, Xi'an 710069, Shaanxi, China.
authors.forename: Daidi
authors.initials: D
authors.lastname: Fan
authors.affiliation: Department of Chemistry, Hong Kong Baptist University, Waterloo Road, Kowloon Tong, Hong Kong, China.
authors.forename: Wai-Kwok
authors.initials: WK
authors.lastname: Wong
authors.affiliation: Department of Chemistry and Biochemistry, The University of Texas at Austin, 1 University Station A5300, Austin, TX 78712-0165, United States.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Jones
authors.affiliation: MOE Laboratory of Bioinoragnic and Synthetic Chemistry/KLGH EI of Environment and Energy Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, Guangdong, China.
authors.forename: Chengyong
authors.initials: C
authors.lastname: Su
mesh_terms: D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000737:chemistry; D018360:Crystallography, X-Ray; D005029:Ethylenediamines / Q000737:chemistry*; D028581:Lanthanoid Series Elements / Q000138:chemical synthesis* / Q000737:chemistry; D008024:Ligands; D049449:Luminescence; D012545:Schiff Bases / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D019265:Spectroscopy, Near-Infrared; D013696:Temperature
chemical_list: D056831:Coordination Complexes; D005029:Ethylenediamines; D028581:Lanthanoid Series Elements; D008024:Ligands; D012545:Schiff Bases; C011452:disalicylaldehyde ethylenediamine
keywords: Heterometallic Zn(2)Ln-arrayed or Zn(2)Ln(3)-arrayed complexes; Mixed anions; Sensitization of NIR luminescence; Temperature dependence for demetalation