title: Two- and three-dimensional lanthanide complexes: synthesis, crystal structures, and properties.
abstract: 3,5-pyrazoledicarboxylic acid (H3L) reacts with nitrate salts of lanthanide(III) (Ln=Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, and Er) under hydrothermal conditions to form a series of lanthanide polymers 1-9. These nine polymers have the same crystal system of monoclinic, but they exhibit three different kinds of metal-organic framework structures. The complexes {[Ln2(HL)3(H2O)4].2H2O}n (Ln=Pr (1), Nd (2), and Sm (3)) were isostructural and exhibited porous 3D frameworks with a Cc space group. The complexes {[Ln2(HL)3(H2O)3].3H2O}n (Ln=Eu (4), Gd (5), and Tb (6)) were isostructural and built 2D double-decker (2DD) frameworks with a P21/c space group. The complexes {[Ln(HL)(H2L)(H2O)2]}n ((Ln=Dy (7), Ho (8), and Er (9)) were also isostructural and formed 2D monolayer (2DM) frameworks with a P21/n space group. The structure variation from the 3D porous framework to the 2D double-decker to the 2D monolayer is attributed to the lanthanide contraction effect. Notably, six new coordination modes of 3,5-pyrazoledicarboxylic acid were observed, which proved that 3,5-pyrazoledicarboxylic acid may be used as an effective bridging ligand to assemble lanthanide-based coordination polymers. The photophysical and magnetic properties have also been investigated.
authors.affiliation: Department of Chemistry, Nankai University, Tianjin 300071, People's Republic of China.
authors.forename: Jun
authors.initials: J
authors.lastname: Xia
authors.forename: Bin
authors.initials: B
authors.lastname: Zhao
authors.forename: Hong-Sheng
authors.initials: HS
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Shi
authors.forename: Yue
authors.initials: Y
authors.lastname: Ma
authors.forename: Hai-Bin
authors.initials: HB
authors.lastname: Song
authors.forename: Peng
authors.initials: P
authors.lastname: Cheng
authors.forename: Dai-Zheng
authors.initials: DZ
authors.lastname: Liao
authors.forename: Shi-Ping
authors.initials: SP
authors.lastname: Yan