Ligand-based luminescence in lead-containing complexes: The effect of conjugated organic ligands on fluorescence

The asymmetrically substituted heterocyclic alkyne 5-(pyridin-3-ylethynyl) picolinate (P3PA) was synthesized via a one-pot Sonogashira coupling. After purification, P3PA was reacted with Pb(NO₃)₂ into the two-dimensional coordination polymer Pb(P3PA)₂(H₂O)₂ (1) under hydrothermal conditions. Coordination polymer 1 crystallizes into the monoclinic space group I2/a, with a = 15.5775(10) Å, b = 5.9949(4) Å, c = 24.8380(16) Å, and β = 90.7500(10)°. In addition, the luminescent fluorene-based ligands, fluorene-9-carboxylate (FCA) and fluorenone-2,7-dicarboxylate (FDCA), were incorporated into hybrid materials via coordination to the lead (II) cation. Coordination polymer Pb(FCA)₂ (2) crystallizes in the monoclinic space group P2₁/c (a = 8.0518(9) Å, b = 25.338(3) Å, c = 10.5842(12) Å, β = 94.913(2)°), and forms a 1-D polymeric chain. Coordination polymer Pb₃(FDCA)₃(H₂O)₃ (3) crystallizes in the triclinic space group P1 (a = 6.6990(5) Å, b = 10.1529(7) Å, c = 13.6935(9) Å, α = 81.884(2)°, β = 87.260(2)°, γ = 84.399(2)°), and forms pillared 3-D layers. These three compounds have been identified via single crystal X-ray diffraction and characterized via powder X-ray diffraction, UV–Vis spectroscopy, and fluorescence spectroscopy.     

Two zincophosphite frameworks templated by 1,4-diaminobenzene: syntheses and structures of C6N2H10·Zn(HPO3)2 and (C6N2H8)0.5·ZnHPO3

The solution-mediated syntheses and single crystal structures of C₆N₂H₁₀·Zn(HPO₃)₂ (I) and (C₆N₂H₈)_0.5·ZnHPO₃ (II) are reported. Slight variation of the synthesis conditions led to two quite different phases. I contains infinite chains of ZnO₄ and HPO₃ groups with the protonated organic moiety acting as a template and interacting with the chains by NH⋯O hydrogen bonds and possible CH⋯O interactions. In II, the neutral 1,4-diamino benzene molecule bonds to Zn (as a ligand) and an unusual composite, “pillared”, structure results, with the organic species bridging 6³ polyhedral sheets, although NH⋯O bonds are also present. Similarities and differences to other zinc phosphites and phosphates are briefly discussed for I and II. Crystal data: C₆N₂H₁₀·Zn(HPO₃)₂, M_r=335.48, monoclinic, C2/c (No. 15), a=17.2471 (14) Å, b=9.0720 (8) Å, c=7.6529 (6) Å, β=103.752 (2)°, V=1163.09 (7) Å³, Z=4, R(F)=0.038, wR(F²)=0.084. (C₆N₂H₈)_0.5·ZnHPO₃, M_r=199.42, orthorhombic, Pbca (No. 61), a=8.0314 (16) Å, b=8.1299 (16) Å, c=18.830 (4) Å, V=1229.5 (4) Å³, Z=8, R(F)=0.026, wR(F²)=0.055.     

Synthesis and structural characterization of a novel two-dimensional 3d-4f heterometallic coordination framework based on pentanuclear lanthanide cluster

A novel 3d-4f heterometallic coordination polymer, {[Tm₅(μ₃-OH)₂(BDC)₆(IN)₂Cu(H₂O)₂]·(H₂O)₃}_n (1) [BDC = benzene-1,2-dicarboxylate, IN = isonicotinate], has been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction, FTIR, elemental analysis, powder X-ray diffraction and thermogravimetric analysis. The compound crystallizes in monoclinic system, space group P2₁/c (No. 14), a = 13.7302(5) Å, b = 23.5428(3) Å, c = 21.5789(2) Å, β = 91.491(3)°, V = 6973.0(3) ų, and Z = 4. The structure exhibits unusual two-dimensional Tm-carboxylate layer, which is constructed from the expansion of novel pentanuclear {Tm₅} clusters. More interestingly, the heterometallic Cu(I) ions were successfully planted into such Ln-carboxylate layer by the bifunctional IN bridging ligands, resulting in the formation of an unprecedented 2D heterometallic lanthanide-transition-metal framework.     

Synthesis,structure and fluorescence of a novel three-dimensional inorganic–organic hybrid polymer constructed from trimetallic clusters and mixed carboxylate ligands

A new inorganic–organic hybrid framework coordination polymer, Cd₃(BDC)_0.5(BTC)₂(DMF)(H₂O)·3DMF·H₃O·H₂O 1, in which two carboxylate ligands, 1,4-benzenedicarboxylic acid (H₂BDC) and 1,3,5-benzenetricarboxylic acid (H₃BTC), coordinate with cadmium ions, has been synthesized under mild conditions and its structure solved by single-crystal X-ray diffraction (XRD) analysis. Polymer 1 crystallizes in the monoclinic system, space group P2₁/c (No. 14) with a=15.750(3) Å, b=14.501(3) Å, c=19.363(4) Å, β=113.67(3)°, V=4050.4(14) Å³, Z=4, R1=0.0374 and wR2=0.1148. Its structure revealed that the nine vertices of the secondary building units are linked by benzene rings from both H₃BTC and H₂BDC ligands to form a 3D network with 10×10 Å channels along [001] direction. Complex 1 is characterized by inductively coupled plasma analysis, powder XRD, infrared spectroscopy and thermogravimetric analysis. Polymer 1 exhibits intense fluorescence at 358 and 377 nm with λ_excitation=208 nm in the solid state at room temperature.     

Solvothermal synthesis and structural characterization of a novel erbium(III)-carboxylate polymeric complex

A novel erbium(III)-carboxylate polymeric complex [{Er(H₂btec)_2/4(btec)_3/6(H₂O)}·2H₂O] _n , simplified as ECPC, (H₄btec=1,2,4,5-benzenetetracarboxylic acid) was synthesized under solvothermal conditions (H₂O/acetic acid). ECPC obtained was characterized by differential thermal analysis/thermogravimetry (DTA/TG), single-crystal X-ray diffraction, elemental analysis and FT-IR analysis techniques. The result of single-crystal X-ray diffraction analysis shows that the ECPC crystallizes in monoclinic symmetry, and the space group P2(1)/n, a=10.6933(15) Å, b=7.1243(10) Å, c=17.092(2) Å, α=γ=90°, β=97.109(2)°, V=1292.1(3) Å³, Z=4, R ₁=0.0286, wR ₂=0.0686. ECPC demonstrates a 3-D supramolecular framework containing nine-coordinate erbium centers and channels. The uncoordinated water molecules occupy the channels in ECPC. The results of TG/DTA, IR and elemental analysis performed also give positive information of the proposed crystal structure.     

Synthesis and characterization of a new organically templated open-framework beryllium phosphite with 3, 4-connected networks

Employing diethylenetriamine (=dien) as a structure-directing agent, a new open-framework beryllium phosphite H₂dien·Be₃(HPO₃)₄ (1), has been synthesized hydrothermally and structurally characterized by single crystal X-ray diffraction. The structure of 1 features a (3, 4)-connected framework with 8- and 12-ring channels, which is constructed from strictly alternating BeO₄ tetrahedra and HPO₃²⁻ pseudopyramids. The 3-D framework possesses a pcu topology when the heptameric [Be₃(HPO₃)₄] clusters are regarded as 6-connected secondary building units. Crystal data: 1, monoclinic, C2/c (no. 15), a = 8.7350(3) Å, b = 15.1704(6) Å, c = 13.0851(4) Å, β = 101.223(5)°, V = 1700.79(10) Å³, Z = 4, R₁ = 0.0625, wR₂ = 0.1692.     

A new paratungstate-A-based organic–inorganic hybrid compound: Synthesis,structure and photocatalytic property of [Co(en)3]2[H2W7O24]·8H2O

A new paratungstate-A-based organic–inorganic hybrid compound with the chemical formula of [Co(en)₃]₂[H₂W₇O₂₄]·8H₂O (en = ethylenediamine) (1) has been hydrothermally synthesized and structurally characterized by the elemental analysis, IR, TG, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic space group P2₁/c with a = 17.216(3) Å, b = 14.986(3) Å, c = 23.088(8) Å, β = 128.151(2)°, V = 4684.2 Å³, Z = 1, R₁ = 0.0484, and wR₂ = 0.1087. The structure of 1 consists of the [H₂W₇O₂₄]⁴⁻ building blocks and [Co(en)₃]²⁺ metal-organic cationic moieties, which are packed together via the electrostatic forces and extensive hydrogen-bonding interactions to form a three-dimensional supramolecular framework. Interestingly, compound 1 represents the first structurally-defined hybrid compound based on the metastable paratungstate-A polyoxoanions and metal–organic units. The degradation of Rhodamine-B (RhB) under UV irradiation with 1 as the heterogeneous photocatalyst has been investigated, showing a good photocatalytic property of 1 for RhB degradation.     

Synthesis,growth, structure and characterization of nickel(II)-doped hexaaquacobalt(II) dipotassium tetrahydrogen tetra-o-phthalate tetrahydrate crystals

Single crystals of K₂[Co_(1−x)Ni_x(H₂O)₆] (C₈H₅O₄)₄·4H₂O (x = 0.25) (PCNHP), a semiorganic black colored transparent crystal of size ∼20 × 13 × 4 mm³, are grown from an aqueous solution of potassium hydrogen phthalate enriched with cobalt chloride and nickel chloride by slow evaporation solution growth technique at room temperature. Structural analysis by single crystal X-ray diffraction reveals that the crystal belongs to monoclinic system with space group P2₁/c and the cell parameters are a = 10.41(3) Å, b = 6.84(2) Å, c = 29.46(9) Å, Z = 4. Incorporation of both Co(II) and Ni(II) into the potassium hydrogen phthalate (KHP) crystal lattice is well confirmed by EDS and chemical tests. Powder XRD profiles indicate the crystallinity and FT-IR studies reveal the vibrational patterns. The UV–vis optical absorption spectrum of PCNHP shows the lower optical cut-off at ∼300 nm and the crystal was transparent in the entire visible region. The crystalline perfection of the grown crystal analysed by high-resolution X-ray diffraction (HRXRD) analysis reveals that the diffraction curve (DC) contains multi-peaks with low angular spread indicating the possibility of low angle structural grain boundaries. Scanning electron microscope (SEM) studies indicate the structure defect centers. The dielectric, thermal and mechanical behaviors of the specimen were also investigated.     

A novel mixed-metal borate with large [B12O18(OH)6]6- motif: Synthesis,structure and property

A new mixed-metal polyborate, Na₅Li[B₁₂O₁₈(OH)₆]·2H₂O (1), has been synthesized using solvothermal method and characterized by IR spectroscopy, thermogravimetric analysis, UV–Vis spectroscopy, powder and single-crystal X-ray diffraction, respectively. It crystallizes in the trigonal space group R-3c (No. 167) with unit cell parameters of a = b = 9.6767(6) Å, c = 36.358(5) Å, and Z = 6. Its structure features unprecedented 3D framework constructed from novel honeycomb-shaped inorganic Na-O sheets with unique 12-MR sodium rings and supramolecular polyborate 2D layers of lithium-centered [B₁₂O₁₈(OH)₆]^6-. UV–Vis spectral characterization indicates that compound 1 is a wide-band-gap semiconductor.     

Two new layered inorganic–organic hybrids: intercalation of 1,3,5-benzenetricarboxylate in lead bisphosphonate

Hydrothermal reactions of N-benzyl-iminobis(methylenephosphonic acid), C₆H₅CH₂N(CH₂PO₃H₂)₂ (H₄L), with lead(II) carbonate in the presence of butane diacid resulted in a new layered lead(II) amino-bisphosphonate, namely, Pb₃L(H₂L)·1.5H₂O 1. When 1,3,5-benzene-tricarboxylic acid (H₃BTC) was used instead of butane diacid, a new layered lead(II) amino-bisphosphonate containing noncoordinated H₃BTC molecules, Pb₃(HL)₂·2(H₃BTC)·2H₂O 2 was isolated. Compound 1 crystallizes in the monoclinic space group P2₁/c with cell dimensions of a=17.6776(14) Å, b=10.0111(8) Å, c=16.6017(13) Å, β=104.134(2)° and Z=4. Compound 2 crystallizes in triclinic space group P-1 with cell parameters of a=4.8797(4) Å, b=9.9736(7) Å, c=24.3631(17) Å, α=97.680(2)°, β=95.0000(10)°, γ=102.4340(10)° and Z=1. Both compounds feature a layered structure and have a same metal/ligand ratio of 3:2. Compound 1 contains two types of ligands with different charges, −2 and −4, respectively. The lead(II) ions are bridged by bisphosphonate ligands, resulting in a 〈100〉 layer. In compound 2, the interconnection of the lead(II) ions by bridging phosphonate groups resulted in a 〈001〉 layer, with the neutral H₃BTC ligand intercalated between two layers, forming hydrogen bonds with lattice water molecules, noncoordinated phosphonate or carboxylate groups. In both compounds, the phenyl groups of the ligands are orientated toward the interlayer space. TGA and IR spectra for both compounds have been also studied.     

Comparative study of two layered lanthanide dicarboxylates based on europium(III) dimers

The new rare-earth dicarboxylate solid Eu₂(H₂O)₄{C₆H₁₀–(CO₂)₂}₃·2H₂O or MIL-94 has been isolated under hydrothermal conditions. Its layered structure, which was solved using X-ray powder diffraction data, is built up from dimers of nine-coordinated edge-sharing polyhedra linked through 1,3-cyclohexane dicarboxylate (1,3-CHC) moieties. A comparative study of MIL-94 and the layered lanthanide dicarboxylate EuBDC or Eu₂(H₂O)₂{C₆H₄–(CO₂)₂}₃, which is built up from dimers of corner-sharing polyhedra and 1,3-benzenedicarboxylate (1,3-BDC) linkers, is also reported. Crystal data for MIL-94: orthorhombic space group Pnma (no. 62) with a = 8.8470(1) Å, b = 25.0148(1) Å, c = 14.3716(4) Å and Z = 4. MIL stands for Material Institut Lavoisier.     

Two novel Keggin tungstocobaltates grafted by cobaltII complex group(s): K[Co(phen)2(H2O)]2[HCoW12O40]·2H2O and [Co(2,2′-bipy)3]1.5{[Co(2,2′-bipy)2(H2O)][HCoW12O40]}·0.5H2O

Two novel inorganic–organic hybrid compounds composed of Keggin tungstocobaltate framework and cobalt(II)–N coordination complexes, K[Co(phen)₂(H₂O)]₂[HCoW₁₂O₄₀]·2H₂O (1) (phen = 1,10-phenanthroline) and [Co(2,2′-bipy)₃]_1.5{[Co(2,2′-bipy)₂(H₂O)][HCoW₁₂O₄₀]·0.5H₂O (2) (bipy = bipyridine), have been synthesized under hydrothermal conditions by directly using Keggin POMs as starting materials, which were characterized by elemental analyses, IR, TG analyses and X-ray single crystal diffraction. Crystal data for compound 1: C₄₈H₄₁Co₃KN₈O₄₄W_12, triclinic, space group P-1, a = 10.918(5) Å, b = 13.401(5) Å, c = 13.693(5) Å, α = 69.291(5)°, β = 71.568(5)°, γ = 78.421(5)°, V = 1768.9(12) Å³, Z = 1; for compound 2: C₁₃₀H₁₀₄Co₇N₂₆O₈₃W_24, orthorhombic, space group, C2/c, a = 46.839(9) Å, b = 14.347(3) Å, c = 26.147(5) Å, α = β = γ = 90°, V = 17,570(6) Å³, Z = 4. Compound 1 exhibits a pseudo-1D chainlike structure, in which potassium ions act as linkages of Keggin unit doubly grafted by [Co(phen)₂(H₂O)] complex. Compound 2 represents a [Co(2,2′-bipy)₂(H₂O)]²⁺ mono-grafted Keggin tungstocobaltate derivative with 1.5[Co(2,2′-bipy)₃]²⁺ countercations. The cyclic voltammetric behavior of 1-CPE is similar to the parent 3-CPE, but the cyclic voltammetric behavior of Co^II shows a little difference. Variable-temperature magnetic susceptibility measurement of compound 1 demonstrates the presence of antiferromagnetic interactions.     

Synthesis,characterization and NLO properties of a new 3D coordination polymer assembled from p-aminobenzoic acid

Reaction of Zn(NO₃)₂·6H₂O with p-aminobenzoic acid in a 1:2 molar ratio under ethanol medium at room temperature affords a new three dimensional (3D) coordination polymer [Zn(PABA)₂]·H₂O (1) (PABA = p-aminobenzoic acid). Single-crystal X-ray diffraction reveals that 1 crystallizes in the orthorhombic system, space group P2₁2₁2₁, a = 7.614(2), b = 11.133(3), c = 16.869(4). 1 adopts a 3D open framework with H₂O molecules in the cavities. PABA, acting as bridging ligand as well as coordinating ligand, adopts a different coordination mode to bridge Zn atoms and form the 3D supramolecular structure which is further stabilized by N–H?O, O–H?O hydrogen bonding and π–π stacking interactions. Powder second-harmonic generation (SHG) efficiency measurement with Nd:YAG laser (1064 nm) radiation shows that the SHG efficiency of 1 is equivalent to KDP crystal. The present work also demonstrates that the framework of 1 is retained after removal of the guest H₂O molecules, and the H₂O molecules can be reintroduced into the framework, indicating that this complex may also be used to generate porous materials.     

One-dimensional coordination polymers generated from an oxadiazole-containing N,N′-bipyridine-type ligand and inorganic salts

Three new one-dimensional coordination polymers have been prepared using Hg(II), Ag(I) and Zn(II) inorganic salts in combination with 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (L6). The compounds were characterized by single crystal X-ray diffraction, IR spectroscopy, and elemental analysis. In the solid state, compounds 1 and 3 (1: monoclinic, P2₁/n, a=5.5373(3) Å, b=16.7839(9) Å, c=16.8120(9) Å, β=92.8610(10)°, V=1560.52(15) ų, Z=4; 3: monoclinic, P2₁/n, a=7.2958(4) Å, b=11.7214(6) Å, c=16.3979(9) Å, β=101.1150(10)°, V=1375.99(13) Å³, Z=4) feature novel one-dimensional helical chain motif. Compound 2, however, (2: monoclinic, P2₁/c, a=5.5506(4) Å, b=16.5895(12) Å, c=16.6871(11) Å, β=95.424(2)°, V=1529.70(19) ų, Z=4) exhibits one-dimensional zigzag chain motif, which result from the different conformations adopted by the L6 ligand and also the different metal coordination geometry. The luminescent properties of three new compounds were investigated in the solid state.     

Two fumarato-bridged Co(II) coordination polymers: syntheses,crystal structures and properties of Co(H2O)4L and [Co3(H2O)4(OH)2L2]·2H2O with H2LHOOCCHCHCOOH

Two fumarato-bridged Co(II) coordination polymers Co(H₂O)₄L 1 and [Co₃(H₂O)₄(OH)₂L₂]·2H₂O 2 with H₂LHOOCCH CHCOOH were prepared. Complex 1 consists of polymeric chains _∞¹[Co(H₂O)₄(C₄H₂O₄)_2/2], which result from octahedrally coordinated Co atoms bridged by bis-monodentate fumarate anions and are assembled by interchain hydrogen bonds. Within 2, the edge-shared Co₂O₁₀ bi-octahedra are connected to the CoO₆ octahedra to form 1D cobalt oxide chains and 3D open framework generated from the chains inter-linked by bis-bidentate fumarate anions displays rhombic tunnels, which are filled with the lattice H₂O molecules. Thermal and magnetic behaviors of both the title coordination polymers are discussed. Crystal data: (1) monoclinic, P2₁/c, Z=4, a=7.493(1) Å, b=14.377(1) Å, c=7.708(1) Å, β=99.54(1)°, V=818.9(2) Å³, R₁=0.0304, and wR₂=0.0669 for 1487 observed reflections (I⩾2σ(I)) out of 1877 unique reflections; (2) monoclinic, P2₁/c, Z=2, a=6.618(1) Å, b=8.172(2) Å, c=15.578(3) Å, β=96.30(3)°, V=837.4(3) Å³, R₁=0.0360 and wR₂=0.0663 for 1442 observed reflections (I⩾2σ(I)) out of 1927 unique reflections.     

Ce(H2O)(PO4)3/2(H3O)1/2(H2O)1/2, a second entry in the structural chemistry of cerium(IV) phosphates

A cerium(IV) phosphate has been prepared using precipitation methods and its structure has been solved by single crystal X-ray diffraction (R₁ = 0.0292 for 3092 reflections with I>2σ(I) and wR₂ = 0.0540). Ce(H₂O)(PO₄)_3/2(H₃O)_1/2(H₂O)_1/2 crystallises in the monoclinic space group C2/c (a = 15.7058(17) Å, b = 9.6261(9) Å, c = 10.1632(4) Å, ß = 121.623(7)°, and V = 1308.4 (2) Å³). Its structure is based on a negatively charged 3D framework, made of cerium atoms connected by PO₄ tetrahedra. There are two types of PO₄ units; one shares only corners with the cerium coordination polyhedra while the other one shares edges and corners. This structure also includes hydronium cations, to balance the framework charge, and water molecules. One special feature of this 3D framework is the formation of interconnected tunnels which extend along the c axis and contain the hydronium cations and the water molecules. This open framework and the presence of cationic species in the tunnels are in perfect agreement with the previously reported ion exchange properties.     

Synthesis and structure of a new scorpionate-dithio carboxyl oxovanadium complex and an organic dithio carboxyl compound

A new complex of oxovanadium(IV), V₂O₂[(HB(pz)₃)₂(pyrro)₂ (1) and a dimer-dithio carboxyl compound (C₅H₈NS₂)₂ (2) have been synthesized by the reaction of VOSO₄·nH₂O with NaHB(pz)₃ and pyrrolidine dithio carboxylic acid ammonium salt. They were characterized by element analysis, IR spectra, UV–vis spectra and X-ray diffraction. Structural analyses of 1 and 2 gave the following parameters: 1, triclinic, P-1, a = 7.732(4) Å, b = 14.285(8) Å, c = 17.802(9) Å, α = 101.314(8)°, β = 92.682(9)°, γ = 92.228(9)°, V = 1923.6(18) Å³, and Z = 4; 2, monoclinic, C2/c, a = 13.857(2) Å, b = 10.4213(18) Å, c = 9.436(2) Å, β = 97.099(2), V = 1352.1(4) Å³, and Z = 4. In complex 1, vanadium atom adopts a distorted tetragonal bipyramid structure, which is typical for oxovanadium(IV) complexes. Compound 2 is a dimer-dithio carboxyl compound with S–S bond. In addition, thermal analysis was performed for analyzing the stabilization of the complexes.     

Synthesis and characterization of a novel three-dimensional open-framework: Metal diphosphonate,Zn[HO3PCH2(C6H4)CH2PO3H]

A novel zinc diphosphonate, Zn[HO₃PCH₂(C₆H₄)CH₂PO₃H] (1) was synthesized from tetraethyl para-xylylenediphosphonate, Et₂O₃PCH₂C₆H₄CH₂PO₃Et₂, and Zn (AcO)₂·2H₂O under solvothermal conditions. The structure of compound 1 was determined by single-crystal X-ray diffraction, which reveals that the structure crystallizes in the monoclinic space group C2/c (No. 15), with a = 22.4844(19) Å, b = 6.4361(5) Å, c = 8.1194(7) Å, β = 102.595(2)°, V = 1146.70(16) Å³, T = 298(2) K, Z = 8. The novel three-dimensional (3D) construction is simply built up from linear inorganic chains of corner-sharing four-rings of tetrahedral [ZnO₄] and [PO₃C] which connected adjacent chains by the organophosphorus ligand para-xylylenediphosphonate. The framework has 10 Å × 4 Å (containing the van der Waals radii of atoms) channels running along the b-axis.