title: Luminescent, magnetic and ferroelectric properties of noncentrosymmetric chain-like complexes composed of nine-coordinate lanthanide ions.
abstract: Reaction of the chiral ligand (-)-4,5-pinenepyridyl-2-pyrazine (L) with Ln(hfac)3·2H2O precursors [hfac(-) = 1,1,1,5,5,5-hexafluoroacetylacetonate, Ln = Sm(3+) (1), Eu(3+) (2), Tb(3+) (3) and Dy(3+) (4)] in methanol solution led to the formation of four noncentrosymmetric lanthanide complexes with the general formula [Ln(hfac)3L]n·H2O. The single-crystal X-ray diffraction analyses revealed that they are isostructural and take a one-dimensional (1D) chain structure based on the Ln(hfac)3L repeating units, in which the nine-coordinate Ln(3+) ions reside in a tricapped trigonal prism (TTP) environment never reported in previous 1D chain lanthanide complexes. The investigations of their photophysical properties showed that complexes 1, and 3 exhibit characteristic emissions of Sm(3+), Eu(3+) and Tb(3+) ions with respective luminescent lifetime values of 0.065, 1.066 and 0.129 ms, while complex 4 does not display any emission. The different luminescent intensities and lifetimes among them were further discussed in detail. Moreover, the magnetic properties of complexes 1-4 were assessed with a special emphasis on the Dy(3+) complex 4. Alternating-current (ac) magnetic susceptibility measurements indicated that field-induced two-step slow magnetic relaxation processes were observed in 4, indicating the single-molecule magnet (SMM) behavior of 4. In addition, the noncentrosymmetric complexes 1-4 crystallizing in the same polar point group (Cs) exhibit both ferroelectric and nonlinear optical properties at room temperature. All these features make them multifunctional crystalline molecule materials.
authors.affiliation: Henan Provincial Key Laboratory of Surface and Interface Science, Zhengzhou University of Light Industry, Zhengzhou 450002, China. lixl@zzuli.edu.cn smfang@zzuli.edu.cn.
authors.forename: Xi-Li
authors.initials: XL
authors.lastname: Li
authors.forename: Chun-Lai
authors.initials: CL
authors.lastname: Chen
authors.forename: Hong-Ping
authors.initials: HP
authors.lastname: Xiao
authors.forename: Ai-Ling
authors.initials: AL
authors.lastname: Wang
authors.forename: Cai-Ming
authors.initials: CM
authors.lastname: Liu
authors.forename: Xianjun
authors.initials: X
authors.lastname: Zheng
authors.forename: Li-Jun
authors.initials: LJ
authors.lastname: Gao
authors.forename: Xiao-Gang
authors.initials: XG
authors.lastname: Yang
authors.forename: Shao-Ming
authors.initials: SM
authors.lastname: Fang