Kecai Xiong

Visible and NIR Photoluminescence Properties of a Series of Novel Lanthanide–Organic Coordination Polymers Based on Hydroxyquinoline–Carboxylate Ligands

A series of novel two-dimensional (2D) lanthanide coordination polymers with 4-hydroxyquinoline-2-carboxylate (H(2)hqc) ligands, [Ln(Hhqc)(3)(H(2)O)](n)·3nH(2)O (Ln = Eu (1), Tb (2), Sm (3), Nd (4), and Gd (5)) and [Ln(Hhqc)(ox)(H(2)O)(2)](n) (Ln = Eu (6), Tb (7), Sm (8), Tm (9), Dy (10), Nd (11), Yb (12), and Gd (13); H(2)ox = oxalic acid), have been synthesized under hydrothermal conditions. Complexes 1-5 are isomorphous, which can be described as a two-dimensional (2D) hxl/Shubnikov network based on Ln(2)(CO(2))(4) paddle-wheel units, and the isomorphous complexes 6-13 feature a 2D decker layer architecture constructed by Ln-ox infinite chains cross-linked alternatively by bridging Hhqc(-) ligands. The room-temperature photoluminescence spectra of complexes Eu(III) (1 and 6), Tb(III) (2 and 7), and Sm(III) (3 and 8) exhibit strong characteristic emissions in the visible region, whereas Nd(III) (4 and 11) and Yb(III) (12) complexes display NIR luminescence upon irradiation at the ligand band. Moreover, the triplet state of H(2)hqc matches well with the emission level of Eu(III), Tb(III), and Sm(III) ions, which allows the preparation of new optical materials with enhanced luminescence properties.

Chlorine‐Induced Assembly of a Cationic Coordination Cage with a μ5‐Carbonato‐Bridged MnII24 Core

Chlorine caged in! The chlorine-induced assembly of six shuttlecock-like tetranuclear Mn(II) building blocks generated in situ based on p-tert-butylthiacalix[4]arene and facial anions gave rise to a novel truncated distorted octahedral cationic coordination cage with a μ(5)-carbonato-bridged Mn(II)(24) core.

Thiacalix[4]arene-Supported Kite-Like Heterometallic Tetranuclear ZnIILnIII3 (Ln = Gd, Tb, Dy, Ho) Complexes

Four kite-like tetranuclear Zn(II)Ln(III)3 (Ln= Gd 1, Tb 2, Dy 3, Ho 4) clusters supported by p-tert-butylthiacalix[4]arene (H4BTC4A) have been prepared under solvothermal conditions and structurally characterized by single crystal X-ray diffraction and powder X-ray diffraction (PXRD). In the structures of these four complexes, each of them is capped by two tail-to-tail p-tert-butylthiacalix[4]arene molecules to form a bent sandwich-like unit. The photoluminescent analyses reveal that the H4BTC4A is an efficient sensitizer for Tb(3+) ions in 2. The magnetic properties of complexes 1-4 are also investigated, in which complex 3 exhibits slow magnetization relaxation typical for single molecule magnets.

Solvent and temperature influence structural variation from nonporous 2D -> 3D parallel polycatenation to 3D microporous metal-organic framework

Three novel complexes constructed from the same initial materials, exhibiting the variation of architectures from nonporous 2D → 3D parallel polycatenation based on highly undulating (4,4) nets to 3D microporous pillar-layered network through influencing the interpenetration, have been successfully synthesized under different reaction conditions.

Two dual-emissive Zn(II) coordination polymers with tunable photoluminescence properties

Two novel dual-emissive coordination polymers [Zn2(Hcpop)2(dpe)(H2O)]n·ndpe (1) and [Zn4(cpop)2(dpe)2(μ-OH)2]n·ndpe (2) (H3cpop = 4-(4-carboxyphenoxy)phthalate acid, dpe = 1,2-di(4-pyridyl)ethylene) have been designed and synthesized as promising luminescent materials, which exhibit tunable fluorescence by varying the excitation wavelength.

Auxiliary ligand-directed and counter anion-templated effects on coordination networks based on semirigid 2-aminodiacetic terephthalic acid ligand

Reactions of the semirigid polycarboxylate ligand, 2-aminodiacetic terephthalic acid (H4adtp), with Zn(II) and Cd(II) salts resulted in {[Zn2(adtp)(H2O)2]·2H2O}n (1) and [Cd2(adtp)(μ2-H2O)(H2O)3]n (3), respectively. By introducing auxiliary ligand 4,4′-bipyridine (bpy), two 3D regularly arranged pillared-layered frameworks {[Zn3(adtp)(bpy)1.5(μ3-OH)(H2O)]·NO3·3H2O}n (2a) and {[Cd4(adtp)2(bpy)(H2O)4]·2.5H2O}n (4) were obtained. Complex 1 is characterized as a two-dimensional (2D) layer structure, whereas complex 3 features a three-dimensional (3D) framework with two types of alternately arrayed channels. In complex 2a, the one-dimensional (1D) zinc chains built up of alternately interlinked tetranuclear and dinuclear units are cross-linked into 2D layers, which are further pillared by bpy into a 3D cationic framework with NO3− as counterions. As for 4, a 3D pillared-layer framework is observed and comprises carboxylic μ2-O bridged –M–O–M– chains. The auxiliary ligand bpy exerts a structure-directing effect on the resultant 3D pillared-layer architectures in 2a and 4, wherein μ3-OH bridged tetranuclear metal units or carboxylic μ2-O bridged –M–O–M– chains appear. Additionally, the cationic framework in 2a is strongly dependent on counter anions and the concentration of bpy ligand. The isomorphic {[Zn3(adtp)(bpy)1.5(μ3-OH)(H2O)]·ClO4·3H2O}n (2b) with ClO4− as template and counterions is also obtained. The luminescent properties of 1, 2a, 3 and 4 are investigated in detail. Compared with free H4adtp, complex 3 exhibits a larger blue-shifted emission band. Complex 2a displays tunable photoluminescence by variation of excitation light and temperature due to multi-centers emissions.

Temperature-controlled reduction of Cu(II) and structural transformation on the assembly of coordination network

A novel twofold interpenetrating three-dimensional mixed-valence copper coordination polymer {[CuI2CuII(adtp)(bpy)2]·4H2O}n (1) and a two-dimensional divalence copper layer structure {[CuII4(adtp)2(bpy)3(H2O)2]·3DMF·13H2O}n (2) were solvothermally synthesized from an identical starting mixture at different temperatures. Temperature-control over the structural transformation from 2 to 1 has been studied in detail. Lower temperatures at 65–80 °C favor the formation of 2, while higher temperature at 85 °C prefers to produce 1. Complex 2 in mother solution at 85 °C will completely transform into 1, concomitant with the reduction of some of the Cu2+ ions over 48 h. TG and magnetic properties of the two complexes are all measured and discussed in detail.

Structure and photoluminescent properties of lanthanide coordination polymers based on two isomers of iminodiacetic acid substituted isophthalate and terephthalate ligands

Two isomers, 5-aminodiacetic isophthalic (H4adip) and 2-aminodiacetic terephthalic (H4adtp) acid were employed for syntheses of lanthanide coordination polymers under solvothermal conditions, resulting in three isostructural two-dimensional (2D) layer-assemblies {Me2NH2[Ln(adip)(H2O)]}n (Ln = Eu (1), Tb (2), Sm (3)) and another three isomorphous three-dimensional (3D) frameworks {[Ln2(Hadtp)2]·3H2O}n (Ln = Eu (4), Tb (5), Sm (6)). Complexes 1–3 can be regarded as 3D supramolecular structures consisting of 2D anionic layers assembled by electrostatic interactions with dimethylamine cations, whereas complexes 4–6 are composed of interweaving single-stranded 41 helix and triple-stranded 43 helixes. The luminescent properties of 1–6 are discussed in detail. Due to the good match between the lowest triplet state of the ligand and the resonant energy level of the lanthanide ion, the lanthanide ions in complexes 2 and 5 can be efficiently sensitized by the ligands.

CCDC 869252: Experimental Crystal Structure Determination

Related Article: Kecai Xiong, Feilong Jiang, Yanli Gai, Daqiang Yuan, Lian Chen, Mingyan Wu, Kongzhao Su and Maochun Hong|2012|Chemical Science|3|2321|doi:10.1039/C2SC20264F