The synthesis and crystal structures of three new lanthanide–organic frameworks [Ln(pza)(OH)(H₂O)]_n (Ln = Y(1), Er(2), Yb(3); H₂pza = 2,3-pyrazinedicarboxylic acid) with helical chains and novel 2D (4³)₂(4⁶,6⁶,8³) topology are reported. The topology is obtained by simplifying the dinuclear metal core as a six-connected node and the ligand as a three-connected linker. The upconversion property measurement gives green and red emissions coming from two-photon excitation of Y: Er, Yb codoped coordination polymer and arising from Er^III transitions of ⁴S_3/2/²H_11/2⁴I_15/2 and ⁴F_9/2⁴I_15/2. The magnetic properties of complexes 2 and 3 are also studied.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Three novel zinc complexes [Zn(dbsf)(H₂O)₂] (1), [Zn(dbsf)(2,2′-bpy)(H₂O)]·(i-C₃H₇OH) (2) and [Zn(dbsf)(DMF)] (3) (H₂dbsf = 4,4′-dicarboxybiphenyl sulfone, 2,2′-bpy = 2,2′-bipyridine, i-C₃H₇OH = iso-propanol, DMF = N,N-dimethylformamide) were first obtained and characterized by single crystal X-ray crystallography. Although the results show that all the complexes 1–3 have one-dimensional chains formed via coordination bonds, unique three-dimensional supramolecular structures are formed due to different coordination modes and configuration of the dbsf²⁻ ligand, hydrogen bonds and π–π interactions. Iso-propanol molecules are in open channels of 2 while larger empty channels are formed in 3. As compared with emission band of the free H₂dbsf ligand, emission peaks of the complexes 1–3 are red-shifted, and they show blue emission, which originates from enlarging conjugation upon coordination. Copyright © 2006 John Wiley & Sons, Ltd.

Three novel hexanuclear core-based hydroxidolanthanide coordination polymers [Ln₃(BDC)_3.5(OH)₂(H₂O)₂]·H₂O [Ln = Y (1), Yb (2) and Er (3); BDC = 1,4-benzenedicarboxylate] were prepared by the hydrothermal method. The controlled hydrolysis of lanthanide ions led to an open hexanuclear cluster core. The hexanuclear core containing six (μ₃-OH) bridged Ln^III ions from two asymmetric units adopts a chair-like configuration. It behaves as a building block and is linked by the BDC ligands to form a 3D framework. The guest water molecules occupy the 1D channels in the structure. The upconversion spectra of the Y:Er-Yb codoped coordination polymers have been studied. The distinct upconversion emissions come from two-photon or three-photonexcitation of Y:Er-Yb codoped coordination polymers andarise from Er^III transitions of the type ⁴F_5/2⁴I_15/2,²H_11/2⁴I_15/2, ⁴S_3/2⁴I_15/2 and ⁴F_9/2⁴I_15/2. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Six novel manganese(II) coordination polymers, namely [Mn(oba)(4,4′-bpy)]_n·n(4,4′-bpy) (1), [Mn(oba)(phen)(H₂O)]_n (2), [Mn₂(oba)₂(2,2′-bpy)₂(H₂O)₂]_n·nH₂oba (3), [Mn₂(cca)₂(4,4′-bpy)₂]_n·2n(4,4′-bpy) (4), [Mn(cca)(phen)]_n (5) and [Mn(cca)(2,2′-bpy)]_n·0.25nH₂O (6) [H₂oba = 4,4′-oxybis(benzoic acid); 4,4′-bpy = 4,4′-bipyridine; phen = 1,10-phenanthroline; 2,2′-bpy = 2,2′-bipyridine; H₂cca = p-carboxycinnamic acid] have been synthesised under hydrothermal conditions. Complexes 1 and 4 possess 3D microporous metal-organic frameworks with free 4,4′-bpy ligands in the channels. The Mn^II ions in complex 2 are bridged into 1D infinite double-chain structures, and those in complex 3 are bridged into 1D zigzag chains. Hydrogen bonds cause the formation of 3D supramolecular networks for complexes 2 and 3. Complex 5 is a complicated 3D metal-organic framework, and the Mn^II ions in complex 6 are linked into 2D layers with cavities; interpenetration of these 2D layers results in the formation of a 3D supramolecular network. Magnetic susceptibility measurements indicate that complex 2 displays a weak ferromagnetic interaction between the Mn^II ions with the following parameters: J = 0.462(3) cm^–1, g = 2.0387(6), zJ′ =–0.0062(3) cm^–1 and R = 8.0 × 10^–6. Complex 4 shows antiferromagnetic coupling between the Mn^II ions with J =–0.718(4) cm^–1, g = 1.986(4) and R = 2.3 × 10^–4. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

The one-pot hydrothermal reaction of CuCl₂ with H₂CPOA and 4,4′-bpy results in two new coordination polymers, [Cu(CPOA)(4,4′-bpy)(H₂O)₂]·1.5H₂O (1) and [Cu₂(HCPOA)₄(4,4′-bpy)₄] (2) (H₂CPOA4-carboxyphenoxy acetic acid, 4,4′-bpy4,4′-bipyridine) since CPOA²⁻ anions reach equilibrium with HCPOA⁻ anions in the reaction system. The crystal structure of 1 shows a triple interpenetration CdSO₄-like net with 1D channel, in which lattice water molecules are located. Complex 2 is a ladder-like 1D double chain structure assembled through coordination bonds and O–H···N hydrogen bonds.

Four novel coordination polymers of Ni^II and Co^II with flexible ligands, namely [Ni(oba)(bpe)]_n·nH₂O (1), [Co(oba)(bpe)]_n (2), [Ni₂(oba)₂(bpy)₂(H₂O)₂]_n·nbpy (3), and [Co(oba)(bpy)_1/2]_n (4) [H₂oba = 4,4′-oxybis(benzoic acid), bpe = 1,2-bis(4-pyridyl)ethane, bpy = 4,4′-bipyridine] were synthesised by hydrothermal reactions and characterised by single-crystal X-ray diffraction, elemental analysis and IR spectroscopy. The Ni^II ions in complex 1 are linked by flexible oba and bpe ligands to form square-grid-like corrugated sheets. These sheets are interpenetrated with each other, resulting in the formation of a 3D porous network with lattice water molecules in the channels. The variable temperature X-ray diffraction analysis shows that the framework is stable up to 300 °C despite the complete removal of the lattice water molecules during the heat treatment. Complex 2 can be regarded as possessing a α-polonium-related topology. Triple interpenetration occurs to form a nonporous structure. In complex 3, the oba and bpy ligands link Ni^II ions into 1D train-like boxes. These boxes are entangled, with the aid of hydrogen bonds, leading to the formation of a 3D porous supramolecular architecture. Free bpy ligands reside in the channels. The Co^II ions in complex 4 are linked by oba and bpy ligands to form a complicated 3D coordination polymer. The lattice water molecules in complex 1 and free bpy ligands in complex 3 can be regarded as templates that play an important role in the formation of the porous structures of complexes 1 and 3. The magnetic properties of complexes 1, 2, and 4 have also been investigated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Three porous, 3-D coordination polymers [Pr₄(NDC)₆(H₂O)₆]·2H₂O (1), [Eu₄(NDC)₆(H₂O)₅]·3H₂O (2) and [Yb₂(NDC)₃(H₂O)]·H₂O (3) based on lanthanide 2,6-naphthalenedicarboxylates (NDC) were synthesized by hydrothermal reactions of lanthanide chlorides with NDC and their properties were investigated. Polymers 1, 2 and 3 differ in the coordination environment of the Ln^III ions. Their 3-D networks are reminiscent of the shape of a compressed honeycomb, showing 1-D open channels. The guest water molecules and coordinating water molecules are enclathrated in the channels. The photophysical properties of the Eu³⁺ complex were investigated by high-resolution luminescence spectroscopy. The results indicate that there are four Eu^III ion sites in complex 2, which is in accordance with the results of the single-crystal X-ray diffraction studies. Thermogravimetric and variable-temperature powder X-ray diffraction analyses show that the porous frameworks of this series of complexes are relatively stable. The framework remained even when the guest molecules were lost and did not collapse until the temperature reached 430 °C. The magnetic properties of 2 were also investigated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

We report the hydrothermal synthesis and crystal structure of isostructural lanthanide coordination polymers [Ln₂(NDC)₃(phen)₂]·H₂NDC [Ln = Tb (1), Ho (2) and Yb (3)] that feature 2,6-naphthalenedicarboxylate (NDC) and 1,10-phenanthroline (phen) ligands. The NDC ligands bridge the lanthanide ions in two different modes to form a 3-D porous framework that accommodates large, neutral 2,6-naphthalenedicarboxylic acid molecules as guests in the channels, stabilized through O−H···O hydrogen bonds to the NDC ligand. The effective dimension of the channel is ca. 6.0 × 8.2 Å. Thermogravimetric analysis shows that complex 2 remains stable up to 330 °C, which we confirmed also by powder X-ray diffraction analyses. The framework collapsed upon the loss of the coordinating phen molecules. The Tb complex shows strong evidence of ferromagnetic coupling interactions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Four lanthanide coordination polymers with benzophenone-4,4′-dicarboxylic acid (H₂bpndc) and 1,10-phenanthroline (phen), [Ln₂(bpndc)₃(phen)] (Ln=La (1), Pr (2) and Tb (3)), [Yb(bpndc)₁₅(phen)].05H₂O (4) were obtained through solvothermal synthesis. The crystallographic data show that 1, 2, and 3 are isostructural, the Ln(III) ions in 1, 2 and 3 are all eight- and ten-coordinated, respectively, and thus the Ln(III) ions are connected by bpndc ligands, resulting in an interpenetrating 3D structure. While in 4, the Yb(III) ions are eight-coordinated and connected by bpndc ligands into a 3D structure with 1D rhombic channels, which result from the effect of lanthanide contraction from La(III) to Yb(III) ions, and the bpndc ligands in 1, 2, 3, and 4 display three types of coordination modes.

Lanthanide complexes with a one-dimensional chain, [Ln₂(dpdc)₃(H₂O)₂]_n [Ln = La (1), Pr (2), Eu (3), Tb (4); dpdc = 2,2′-diphenyldicarboxylate] were obtained by hydrothermal reaction of lanthanide(III) chlorides and 2,2′-diphenyldicarboxylic acid, and characterized by X-ray diffraction. The crystal structure data reveal that they are isostructural. In the asymmetric unit, the two Ln³⁺ ions are both eight-coordinate but they have different coordination environments. Lanthanide ions arranged in a zigzag manner are bridged by the dpdc ligands into a 1-D chain, while the structure appears like a pinwheel viewed along the c axis. In these complexes, 2,2′-diphenyldicarboxylate anions exhibit tetradentate and pentadentate coordination modes. A laser-induced highresolution spectrum (resolution: 0.2 cm⁻¹) of 3 was obtained, which shows two Eu³⁺ sites in 3. This is in agreement with the results of single-crystal X-ray diffraction studies of 3. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

In the four new lanthanide coordination polymers {[La₂(2,2′-dpdc)₃(phen)(H₂O)]·2H₂O}_n (1), [Eu₂(2,2′-dpdc)₃(phen)(H₂O)₂]_n (2), {[Ln₂(2,2′-dpdc)₃(phen)₂(H₂O)₂]·4H₂O}_n [Ln = Tb (3), Yb (4)] (2,2′-dpdc = 2,2′-diphenyldicarboxylate, phen = 1,10-phenanthroline), prepared by hydrothermal synthesis, the 2,2′-dpdc dianion affords tetradentate, pentadentate, and hexadentate coordination modes. Complex 1 is a two-dimensional network of infinite 1-D chains assembled through π−π interactions, with nine- and ten-coordinate La³⁺, and arranged in wave-like layers. In 2, Eu³⁺ possesses nine- and ten-coordinate geometries bridged by 2,2′-dpdc ligands to give a 3-D structure. The isomorphous complexes 3 and 4, in which Tb³⁺ and Yb³⁺ ions are both nine-coordinate, have two-dimensional structures of 1-D zigzag chains stacked via hydrogen bonds and π−π interactions of phen molecules. The high-resolution emission spectrum of 2 shows two Eu³⁺ ion sites, which is consistent with the results of the X-ray crystal structure analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Lanthanide 2,3-pyrazinedicarboxylate complexes with three-dimensional frameworks, [Ln₂(pzdc)₃(H₂O)]_x·2xH₂O [Ln = Pr (2), Nd (3), and Eu (4)], were obtained by hydrothermal reactions of 2,3-pyrazinedicarboxylic acid (H₂pzdc) and the lanthanide(III) chlorides, while [La₂(pzdc)₃(H₂O)]_x·2xH₂O (1) was obtained by hydro(solvo)thermal reaction of LaCl₃·7H₂O and 2,3-pyrazinedicarboxylic acid. They are isomorphous and exhibit complicated 3-D structures based on [Ln₂(pzdc)₃(H₂O)] building blocks. In the asymmetric unit, the two Ln³⁺ ions are both nine-coordinate, but with different coordination environments. The ligand pzdc coordinates to the central Ln³⁺ ions in a tetradentate, hexadentate, or heptadentate manner. Utilizing the characteristic of Eu³⁺ ion to act as a conformational probe, we determined the high-resolution spectra of 4, which show that there are two Eu³⁺ ion sites in the coordination polymer. This is also in agreement with the results of the X-ray single-crystal diffraction study. It was concluded that there are two La³⁺, two Pr³⁺ and two Nd³⁺ ion sites in polymers 1, 2, and 3, respectively. The thermogravimetric analyses of these complexes show that all coordinated and uncoordinated water molecules were lost at the first weight loss above 240 °C. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2002)

The novel ytterbium coordination polymer is a two-dimensional framework in which the central metal ions have four different coordination numbers and form four kinds of coordination polyhedra. The four kinds of coordination polyhedra connect into infinite chains by sharing oxygen atoms.

A novel N-Mannich base tris(2, 5-dioxopyrrolidin-1-ylmethyl)-amine (TDOPMA) was synthesized and its structure was determined by single crystal X-ray diffraction. Unlike NH₃ molecule, three C-N-C bond angles containing the central N atom in the tide compound are unequal and about 9° larger than H-N-H angles of NH₃ molecule. Electrospray ionization (ESI) mass spectrometry was applied to the title compound. Its fragments were interpreted and possible fragmentation mechanism was given.