title: Influence of conformational flexibility on self-assembly and luminescence properties of lanthanide coordination polymers with flexible exo-bidentate biphenol derivatives.
abstract: To explore how nonplanar conformational distortions affect supramolecular self-assembly and properties of lanthanide complexes, we have designed and synthesized two new flexible exo-bidentate ligands derived from biphenol featuring two salicylamide pendant arms, 2,2'-bis{[(2'-benzylaminoformyl)phenoxyl]ethoxyl}-1,1'-biphenylene (L(I)) and 5,5'-dibromo-2,2'-bis{[(2'-benzylaminoformyl)phenoxyl]ethoxyl}-1,1'-biphenylene (L(II)). These two structurally related ligands can have different conformations and are used for constructing diverse lanthanide polymers with interesting luminescence properties. Among two series of lanthanide nitrate complexes which have been characterized by elemental analysis, X-ray powder diffraction, and IR spectroscopy, four new coordination polymers have been determined using X-ray diffraction analysis. The coordination polymer type {Ln(2)(NO(3))(6)(L(I))(3).3H(2)O}(infinity) (Ln = Nd, Sm, Eu, Gd, Tb or Dy) displays a two-dimensional honeycomb-like framework in the ab plane, which can be regarded as a (6,3) topological network with neodymium atoms acting as "three-connected" centers. In contrast, the coordination polymer types {[Nd(NO(3))(3)(L(II))(CH(3)OH)] x CH(3)OH}(infinity) and [Ln(NO(3))(3)(L(II))(C(2)H(5)OH)](infinity) (Ln = Sm, Eu, Gd, Tb or Dy) possess single-stranded helix chains which can be further connected through intermolecular hydrogen bonds to form two-dimensional supramolecular sheets. The photophysical properties of trivalent Sm, Eu, Tb, and Dy complexes at room temperature were investigated. The present work substantiates the claim that the supramolecular structure as well as the luminescence properties of the coordination polymer can be tuned by controlling the conformational distortion of a nonplanar flexible ligand in the supramolecular self-assembly.
authors.affiliation: College of Chemistry and Chemical Engineering and State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China.
authors.forename: Yanling
authors.initials: Y
authors.lastname: Guo
authors.forename: Wei
authors.initials: W
authors.lastname: Dou
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Zhou
authors.forename: Weisheng
authors.initials: W
authors.lastname: Liu
authors.forename: Wenwu
authors.initials: W
authors.lastname: Qin
authors.forename: Zhipeng
authors.initials: Z
authors.lastname: Zang
authors.forename: Hongrui
authors.initials: H
authors.lastname: Zhang
authors.forename: Daqi
authors.initials: D
authors.lastname: Wang
mesh_terms: D001713:Biphenyl Compounds / Q000737:chemistry; D018360:Crystallography, X-Ray; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D008024:Ligands; D049449:Luminescence; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*
chemical_list: C540696:2,2'-bis(((2'-benzylaminoformyl)phenoxyl)ethoxyl)-1,1'-biphenylene; C540697:5,5'-dibromo-2,2'-bis(((2'-benzylaminoformyl)phenoxyl)ethoxyl)-1,1'-biphenylene; D001713:Biphenyl Compounds; D028581:Lanthanoid Series Elements; D008024:Ligands; D009942:Organometallic Compounds; D010636:Phenols; D011108:Polymers