Construction of three-dimensional Ln–Ag (Ln = Eu; Tm) coordination polymers based on isonicotinate and oxalate ligands

Hexanuclear 4d–4f heterometallic coordination polymers, [Ln₂Ag₄(IN)₅(ox)₂(NO₃)(H₂O)₂ · 3H₂O] [Ln = Eu (1), Tm (2); IN = isonicotinate and ox = oxalate], have been synthesized by hydrothermal reaction of mixed organic ligands and metal salts. Both structures display the same unusual 3D heterometallic coordination frameworks based on rare zigzag lanthanide–oxalate–silver chains, Ag₂(IN)₃ units and IN linkers. The photoluminescent properties of complex 2 were studied.     

Syntheses and characterizations of two novel Ln(III)–Cu(II) coordination polymers constructed by Pyridine-2,4-dicarboxylate ligand

Two novel three dimension Ln(III)–Cu(II) coordination polymers [Gd₂Cu(pydc)₄(H₂O)₆]_n and [Sm₂Cu₃(pydc)₆(H₂O)₆]_n were prepared by the hydrothermal reactions of CuO, Ln₂O₃ (Ln = Gd, Sm), H₂pydc (H₂pydc = 2,4-pyridinedicarboxylic acid) and characterized by single-crystal X-ray diffraction analysis.     

Novel 3-dimensional sixfold interpenetrating diamondoid networks of copper(I) coordination polymers of polypyridyl ligands – Syntheses,characterization and crystal structures

Two new coordination polymers [Cu(L¹)₂]_n(ClO₄)_n·2nH₂O (1), [Cu(L²)₂]_n(ClO₄)_n·2nH₂O (2) of polydentate imine/pyridyl ligands, L¹ and L² with Cu(I) ion have been synthesized and characterized by single crystal X-ray diffraction studies, elemental analyses, IR′ UV–vis and NMR spectroscopy. They represent 3-dimensional, sixfold interpenetrating diamondoid network structures having large pores of dimension, 35 × 21 Å² in 1 and 38 × 19 Å² in 2, respectively.     

Three rare Ln–Na heterometallic 3D polymers based on sulfate anion: Syntheses,structures, and luminescence properties

Three Ln–Na heterometallic 3D polymers based on sulfate anion, [LnNa(SO₄)₂(H₂O)] (Ln = Gd (1); Tb (2); Dy (3)), were synthesized under hydrothermal conditions, which are the first examples of Ln–Na sulfates. These compounds crystallize in the trigonal P3₁21 space group, and display a 6-connected sma topological structure with a Schäfli symbol of (4¹⁰·6⁵). The characteristic analyses reveal that compounds 1–3 display excellent thermal stability, and all exhibit antiferromagnetic interactions between the metal centers. The luminescent properties of 2 and 3 show the characteristic terbium and dysprosium luminescence. The strong luminescence in the green light (⁵D₄ → ⁷F₅) region for 2 and blue light (⁴F_9/2 → ⁶H_15/2) region for 3 indicate that they may be excellent candidates for green or blue fluorescent materials.     

3D pillar-layered 4d–4f heterometallic coordination polymers based on pyridine-3,5-dicaboxylate and oxalate mixed ligands

Three 4d–4f heterometallic polymers, Ln₂Ag₂(Hpydc)₂(pydc)₂(ox) · 4H₂O (Ln = Nd (1), Eu (2) and Er (3); H₂Pydc = pyridine-3,5-dicarboxylic acid, H₂ox = oxalic acid), have been successfully synthesized under hydrothermal condition and structurally characterized. Single-crystal X-ray diffraction analyses reveal that three compounds are isomorphous and exhibit 3D pillar-layered coordination frameworks constructed from two-dimensional lanthanide-carboxylate layers and [Ag(pydc)]^? pillars. Furthermore, the luminescent property of compound 2 was studied.     

Two d10 coordination polymers based on 4,4′-(hexafluoroisopropylidene)diphthalic acid: Syntheses,structures and physical properties

Two novel coordination polymers, [Zn₂(FA)(4,4′-bipy)₂]·2H₂O (1) and Cd₂(FA)(2,2′-bipy) (2), (H₄FA = 4,4′-(hexafluoroisopropylidene)diphthalic acid, 4,4′-bipy = 4,4′-bipyridine, 2,2′-bipy = 2,2′-bipyridine), have been synthesized under hydrothermal conditions, and their structures were determined by single-crystal X-ray diffraction. Polymer 1 features an unusual three-dimensional (3D) network with (4 · 6² · 8³)(4² · 6² · 8²) topology. Polymer 2 has a complicated 3D framework and crystallizes in non-centrosymmetric space group (Fdd2) belonging to polar point group (C_2v), which displays a strong SHG response and ferroelectric properties. Moreover, the luminescent properties of 1 and 2 have also been investigated.     

Syntheses and structures of cadmium(II) and cobalt(II) coordination polymers based on 1,1′-(2,2′-oxybis(ethane-2,1-diyl))bis(1H-imidazole) and carboxylate ligands

Two novel coordination polymers containing Cd(II) and Co(II) metals, connected via 1,1′-(2,2′-oxybis(ethane-2,1-diyl))bis(1H-imidazole) (L) ligand, have been synthesized. Compound [Cd(L)₂(p-BDC)] · 2H₂O (1) (p-BDC = 1,4-benzenedicarboxylate anion) is a three-dimensional interdigitated supramolecular architecture. Compound [Co(L)(BTCA)_0.5] (2) (BTCA = 1,2,3,4-butanetetracarboxylate anion) possesses a unique (3,4)-connected 3D framework with (8³)₂(8⁵ · 10) topology.     

Construction of three isostructural 3d–4f microporous coordination frameworks based on mixed nicotinate and oxalate ligands

The self-assembly of nicotinic acid and sodium oxalate with mixed 3d–4f metal salts under hydrothermal conditions gave three isostructural 3D 3d–4f coordination polymers, [LnCu(nic)₂(ox)] · xH₂O [Ln = La, x = 1 (1); Ln = Eu, x = 2 (2); Ln = Gd, x = 2 (3)] [ox = oxalate, nic = nicotinate]. All three structures exhibit same unusual 3D microporous heterometallic coordination frameworks that are built up by rare tetranuclear Ln₂Cu₂ clusters and mixed ox and nic linkers. Furthermore, the luminescent property of complex 2 has also been investigated.     

Three Ag(I)–cyanide coordination polymers with metal bonds tuned by N-heterocyclic ligands

Hydrothermal reactions of AgNO₃, K₃[Fe(CN)₆] with N-heterocyclic ligands afforded three novel Ag(I)–cyanide coordination polymers, [Ag₂(CN)₂(tpt)]_n (1), {[Ag(CN)(bpe)_0.5][Ag(CN)]}_n (2) and [Ag(CN)(btmb)_0.5]_n (3) (tpt = 2,4,6-tris(4-pyridyl)-1,3,5-triazine, bpe = 1,2-bis(4-pyridyl)ethane, btmb = 1,2-bis(1,2,4-triazol-1-ylmethyl)benzene). In complex 1, two Ag(CN) linear chains are bridged by bidentate tpt ligand to form a ladder-like structure, which are further connected by AgAg metal bond to generate a 2D polymeric network. Complex 2 is an interesting 3D supramolecular architecture assembled by 2D [Ag¹(CN)(bpe)_0.5]_n network and linear [Ag²(CN)]_n chain combined by strong AgAg metal bond. Complex 3 is a 1D ladder-like double-chain polymer constructed from Ag–cyanide linear chains and btmb spacer, which is further extended to a 2D supramolecular network by Ag–Ag weak interaction. The Ag–Ag metal interactions play important roles in the construction of three coordination polymers. Complexes 1 and 2 are respectively thermally stable at 300 and 180 °C. Complexes 1 and 3 emit strong blue luminescence.     

A novel three dimensional 3d–4f heterometallic coordination framework with 2, 2′-bipyridine-3-carboxylate and oxalate ligands

The 3D heterometallic polymeric complex 1 {[Nd₂Cu₂(L)₂ (OXA)₄·2(2H₂O)]·2(3H₂O)}_n (HL = 2, 2′-bipyridine-3-carboxyic acid, OXA = oxalate) was obtained from hydrothermal reaction of Nd₂O₃, Cu(ClO₄)₂, HL and oxalic acid in the presence of ethanol and water. X-ray single crystal diffraction investigation of the polymeric complexes {[Nd₂Cu₂(L)₂(OXA)₄·2(2H₂O)]·2(3H₂O)}_n exhibits an interesting and novel topological structure.     

One-dimensional salen-type heterospin trimetallic (3d–4f–3d′) chain-like coordination polymers: Syntheses,crystal structures and magnetic properties

Three one-dimensional (1D) heterospin trimetallic chain-like polymers [{LCu(H₂O)}Ln(MeOH)(H₂O)₂{(μ-CN)₂Fe(CN)₄}]·2H₂O (1, Ln = La; 2, Ln = Nd; 3, Ln = Gd) were prepared by substitution of the nitrato ligands in [LCuLn] complexes with [Fe(CN)₆]^3? ions (H₂L = N,N′-bis(3-methoxysalicylidene)propane-1,2-diamine). Single-crystal X-ray diffraction analysis revealed that the methyl on the salen-type ligand impeded the connection between cyanide groups and Cu(II) ions efficiently. Consequently, three novel one-dimensional (1D) trimetallic chain-like polymers were obtained with the linker [Fe(CN)₆]^3? ions interacting only with the lanthanide ions. The magnetic investigation for 3 indicated a ferrimagnetic chain may form.     

Ru(II)–CO complexes of thioarylazoimidazoles: Syntheses,structures, spectroscopy and DFT calculation

The complexes, cis-(CO)-trans-(Cl)-[Ru(SRaaiNR)(CO)₂Cl₂] (2) and trans-(Cl)-[Ru(SRaaiNR)(CO)Cl₂] (3) (SRaaiNR = 1-alkyl-2-{(o-thioalkyl)phenylazo}imidazoles; R = Me (1a) and Et (1b)) have been synthesized and characterized. The structural confirmation is achieved by single crystal X-ray structure determinations. The complexes show Ru(III)/Ru(II) couple and ligand reductions. Electronic structure and spectral properties of the complexes have been explained with the DFT and TDDFT calculation.     

A series of unusual three-dimensional 3d–4f (Ln/Cu/Cl/Br) cyanide heterometallic coordination polymers: Synthesis,crystal structure and magnetic properties

A series of unusual three-dimensional (3D) 3d–4f cyanide heterometallic coordination polymers (HCPs), namely [Ln_1.5Cu₃(ina)₃(ga)(CN)_1.5(X)(H₂O)] [Ln = Dy, X = Cl (1), Ln = Tb, X = Br (2), Ln = Dy, X = Br (3); ina = isonicotinic acid; ga = glycolic acid] have been synthesized via hydrothermal reaction and characterized by single crystal X-ray diffraction, elemental analyses, FT–IR spectroscopy, powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). X-ray structural analysis reveals that HCPs 1 to 3 are constructed from the linkage between Ln–organic layer motifs and double-stranded cyano-containing Cu-inorganic ribbon motifs. In these complexes, the carboxyl group and hydroxyl group of H₂ga are all deprotonated and the coordinated ga ligands adopt a very interesting μ₃-kO:kO,O′:kO′,O″ coordination mode. Moreover, magnetic properties of HCP 1 were investigated.     

Modifying polysulfone into a bidentate Schiff base type macromolecular ligand and study on photoluminescence property of polymer–rare earth complexes of Eu(III) and Tb(III)

Chloromethylated polysulfone (CMPSF) was directly transformed into aldehyde (AL) group-functionalized polymer via Kornblum reaction, and then polysulfone was modified to a bidentate Schiff base (BS) type macromolecular ligand, PSF-ASB, via Schiff base reaction with 3-aminopyridine as reagent. Afterward, luminescent binary and ternary polymer-rare earth complexes, PSF-(ASB)₃-Eu (III) and PSF-(ASB)₃-Eu(III)-(Phen)₁ (o-phenanthroline, Phen), were prepared. The macromolecular ligand PSF-ASB and the complexes were fully characterized by FTIR, ¹H-NMR, UV spectroscopy and TGA. The photoluminescence properties and mechanisms of the complexes were investigated in depth. The experimental results show that the macromolecular ligand PSF-ASB itself emits strong fluorescence. However, after coordinating to Eu(III) ion, its fluorescence intensity weakens remarkably, implying that there occurs an intramolecular energy transfer. The complexes of Eu(III) ion exhibit stronger characteristic fluorescence emission of Eu(III) ion, whereas the complex of Tb(III) ion has no photoluminescence property, indicating that the bonded ligand ASB can effectively sensitize the fluorescence emission of Eu(III) ion and suggesting that the triplet state energy of the bonded ligand ASB is well matched with the resonant state level of Eu(III) ion. More importantly, relative to general polymer-rare earth complexes, for these luminescent polymer-rare earth complexes prepared in this study, the backbone of the macromolecular ligand PSF-ASB also takes part in the sensitization towards Eu(III) ion because of that half of aryl rings of a greater π bond conjugate system of ASB comes from PSF skeleton, displaying a great difference with other luminescent polymer-rare earth complexes.     

Binuclear, 2D grid and 3D interlocking coordination polymers based on 1,2,4,5-benzenetetracarboxylic acid and 4,4′-azobispyridine

Three new nickel(II) complexes [Ni₂(btec)(azopy)₂(H₂O)₈]·2H₂O (1), {[Ni(H₂btec)(azopy)(H₂O)₂]·(azopy)}_n (2) and {[Ni₄(btec)₂(azopy)₃(H₂O)₁₀]·8H₂O}_n (3) (H₄btec = 1,2,4,5-benzenetetracarboxylic acid; azopy = 4,4′-azobispyridine) have been synthesized by tuning the reaction temperature and the metal–ligand ratio. They were characterized by single-crystal X-ray diffraction and elemental analysis. 1 shows a binuclear structure, 2 exhibits a 2D grid, and 3 features an interesting 3D framework with (6³)(4.6²)(4².6².8²) topology formed by two types of interlocked 2D layers.     

Syntheses,structures and properties of a series of 3s–5d–4f mixed metal substituted sandwich-type arsenotungstates

A class of 3s–5d–4f mixed metal substituted sandwich-type arsenotungstates [H₂N(CH₃)₂]₈H₃[LnNa(H₂O)₄(OH)WO(H₂O) (B-α-AsW₉ O₃₃)₂]·8H₂O [Ln = La^III (1), Ce^III (2), Pr^III (3)] have been isolated from an aqueous solution reaction system (pH = 4) of Na₂WO₄·2H₂O, C₂H₇N·HCl, NaAsO₂ and Ln(NO₃)₃·6H₂O and structurally characterized by elemental analyses, IR spectra, UV spectra and single-crystal X-ray diffraction. It is the most prominent in 1–3 that the [LnNa(H₂O)₄(OH) WO(H₂O)(B-α-AsW₉O₃₃)₂]^11 − polyanion consists of two trivacant Keggin [B-α-AsW₉O₃₃]^9 − moieties linked by one [WO(H₂O)]^4 + group and a dimeric [LnNa(H₂O)₄(OH)]^3 + group resulting in the special 3s–5d–4f mixed metal substituted sandwich-type assembly. Interestingly, lanthanide and sodium ions simultaneously occupy the two positions located at the central belt of 1–3 with the site occupancy of 50% for each position. Moreover, the electrochemical and electrocatalytic properties of only 1 and 2 have been measured by cyclic voltammetry (CV) in 0.5 mol·L^− 1 Na₂SO₄ + H₂SO₄ aqueous solution. 1 and 2 illustrate electrocatalytic activities for the hydrogen peroxide reduction.     

Microwave dielectric properties of ceramics based on CaTiO3–LnMO3 System (Ln–La,Nd; M–Al,Ga)

Structural features and microwave dielectric properties of LnMO₃–CaTiO₃ samples (where Ln stands for La or Nd, M stands for Al or Ga) are studied. Solid solutions with the rhombic perovskite structure are shown to be formed with increasing molar concentration of LnMO₃ up to ∼35% (for Ln–Nd, M–Al) or ∼40% (for Ln–La, M–Ga). Further increase of the neodymium aluminate or lanthanum gallate molar content in the solid solution up to 70% leads to formation of solid solutions with the tetragonal perovskite structure. A family of promising ceramics for application in the microwave technology with dielectric permittivity lying within the range from 43 to 48, the dielectric permittivity temperature coefficient being near to zero, and heightened quality factor (Q·f ⩾40,000 GHz) are obtained.     

Synthesis,characterization and luminescence of two unusual 4d–4f Ln–Ag coordination compounds

Two novel Ln–Ag coordination compounds with the formula [LnAg₂(IN)₄(OAC) · 5H₂O] · 2H₂O (Ln = Gd 1, Eu 2; HIN = isonicotinic acid; HOAC = acetic acid) have been synthesized under hydrothermal condition and characterized by single-crystal X-ray diffraction, thermal analysis, IR absorption spectroscopy, ultraviolet excitation and emission spectrum. The two compounds show isostructural architectures and exhibit an unusual 1-D structure, which is formed by the linkages of Ag–Ag.     

Two novel supramolecular isomers based on 2,2′-biimidazole derivative and zinc ions: Syntheses,structures and luminescent properties

Two Zn(II)-2,2′-biimidazole derivative supramolecular isomers 1 and 2 formulated as [Zn(L)] · 2H₂O (H₂L = 4,4′-(1H,1′H-2,2′-biimidazole-1,1′-diylbis(methylene))dibenzoic acid) have been synthesized, and structurally characterized by elemental analysis, IR spectroscopy, single-crystal X-ray crystallography. Complex 1 exhibits a 2D four-connected network with (4³.6³) topology when the zinc center and the L^2? ligand act as four-connected nodes (or a distorted (4,4) grid if the [Zn₂(imidazole)₄] units are considered as four-connected nodes). Complex 2 shows a novel four-connected twofold interpenetrated net with (4².6².8²) topology when the zinc center and the L^2? ligand act as four-connected nodes (or a twofold interpenetrated α-Po topology when [Zn₂(imidazole)₄] units are identified as six-connected nodes). Moreover, complexes 1 and 2 both exhibit strong luminescent properties at room temperature.