Heteronuclear Coordination Polymers Research Articles

Synthesis, characterization and crystal structures of heteronuclear coordination polymers with 4-methylpyridine

Synthesis, characterization and crystal structures of heteronuclear coordination polymers with 4-methylpyridine

Investigation of Intermetallic Energy Transfers in Lanthanide Coordination Polymers Molecular Alloys: Case Study of Trimesate-Based Compounds.

Reactions in water at ambient temperature and pressure between a lanthanide ion and benzene-1,3,5-tricarboxylate (or trimesate) lead to two series of iso-structural coordination polymers. Their general chemical formula is [Ln(tma)(H2O)6]∞ for the lightest lanthanide ions (Ln = La-Dy except Pm), while it is [Ln(tma)(H2O)5·3.5H2O]∞ for the heaviest ones (Ho-Lu plus Y). For the heaviest lanthanide ions, reactions at 50 °C lead to a third structural family with the general chemical formula [Ln(tma)(H2O)3·1.5H2O]∞ with Ln = Ho-Lu plus Y. Homo-lanthanide coordination polymers that belong to the latter two families do not exhibit luminescence in the visible region. Therefore, we used a phase induction strategy to obtain molecular alloys that belong to these structural families and show sizeable emission. The random distribution of the lanthanide ions over the metallic sites has been investigated using 89Y and 139La solid-state NMR spectroscopy experiments. Luminescent properties of homo- and hetero-nuclear coordination polymers based on Eu3+ and Tb3+ have been studied in detail and compared. As a result, this study strongly suggests that exchange-based intermetallic energy transfer mechanisms play an important role in these systems. It also suggests the presence of an intermetallic exchange pathway through π-stacking interactions.

Two-Dimensional Heteronuclear Coordination Polymers Constructed by Cyanide and 3-(2-Aminoethyl)pyridine Ligands

Two new heteronuclear (Ni/Cd and Pd/Cd) 2D coordination polymers formulated as namely {[Cd(μ-3aepy)2Ni(μ-CN)2(CN)2]⋅2H2O}n (1) and [Cd(3aepy)Pd(μ4-CN)4]n (2) (3aepy = 3-(2-aminoethyl)pyridine) were obtained and determined using different techniques (FT-IR and Raman spectroscopies, single crystal X-ray diffraction, elemental, SEM–EDX and thermal analyses). Single crystal X-ray study of the complexes revealed that the Ni(II) and Pd(II) ions are coordinated with four cyanide-carbon atoms in square planar geometries. The Cd(II) ions are bridged by 3aepy ligands to generate [Cd2(3aepy)2]2+ cation and adjacent cations are further linked to cyanide ligands from [Ni(μ-CN)4]2− anion, generating corrugated rectangular grid-like 2D sheets in 1. Whereas, the Cd(II) and Pd(II) ions are bridged by cyanide ligands, generating corrugated rectangular grid-like 2D sheets in 2. The Cd1 is possessed the distorted octahedral coordination geometry with six nitrogen atoms from two 3aepy and four cyanide ligands. The Cd2 is coordinated by four nitrogen atoms from cyanide ligands to form a square-planar geometry. Furthermore, the most remarkable properties of the complexes are the existence of the intermolecular C–H⋯M interactions between M(II) and hydrogen atoms of the 3aepy ligands (M(II) = Ni and Pd).

Luminescence properties of lanthanide complexes-based molecular alloys

Six lanthanides complexes with chemical formula [Ln(phen)2(NO3)3] (Ln = Sm(1), Tb(2), Nd(3), Eu(4), Ho(5) and Y(6), phen = 1,10-phenanthroline) were synthesized. 1 and 2 were obtained as single crystals by slow diffusion. Structural characterization was based on single crystal X-ray diffraction and IR and 89Y-NMR spectroscopies. NMR spectroscopic measurements were performed on [Y(phen)2(NO3)3] (6) and [Y0.75Lu0.25(phen)2(NO3)3] (7). Compounds obtained as microcrystalline powders were characterized by powder X-ray diffraction. The complexes crystallize in the monoclinic system, space group P21/n. Each Ln(III) ion is surrounded by four N atoms from two bidentate phenanthroline ligands and six O atoms from three chelating nitrate groups. The phenanthroline ligand provides efficient sensitization of the complexes that exhibit sizeable luminescence under UV irradiation. Thermal properties have been studied. They confirm the absence of water molecules in the crystal structure. The complexes are thermally stable up to 290 °C. Microcrystalline powders of hetero-lanthanide complexes, with global chemical formula [Tb1−xEux(phen)2(NO3)3] (series8) and [Tb1−xGdx(phen)2(NO3)3] (series9) were synthesized. Their photo-physical properties have been investigated. They demonstrate that luminescent molecular alloys can be obtained from lanthanides complexes and not only from hetero-nuclear coordination polymers as previously reported.

Tunable luminescence modulation and warm light emission of Zn-MOF (4,4′-bipyridyl and zinc acetate) doped with Eu3+ and Tb3+

Abstract Herein, we describe the synthesis and doping of Zn-MOF (4,4′-bipyridyl and zinc acetate), crystallographic structure, optical properties of heteronuclear coordination polymers with emission in the visible (Eu3+/Tb3+ and Zn-MOF). The MOF presents a linear structure in the form of a nanotube. Density functional theory (DFT) and time dependent-DFT calculations were performed on the ground and excited states of Zn-MOF to provide insight of geometries, frontier molecular orbitals, and singlet and triplet state energies of the polymer. The metal-organic framework was doped with Eu3+ or Tb3+ in different proportions (Eu0.5-nTbn@Zn-MOF, when n = 0.00, 0.05, 0.10, 0.15, …, 0.5). The doped Zn-MOFs exhibit the typical red and green emission corresponding to Eu3+ and Tb3+ ions, respectively, energy transfer from MOF to metal ions takes place (“antenna effect”). It is noteworthy that the emission color of the lanthanides doped Zn-MOFs changes from red to orange-yellow-green depending on the proportion between Eu3+ and Tb3+. These compounds presented a τ ranging from 1.29 to 1.62 and 1.06–1.56 ms for Eu3+ and Tb3+, respectively, and the corresponding absolute quantum yields values range from 38 to 61%.

A New Metalloligand Powerful in Forming Helical Coordination Polymers

A new macrocyclic oxamido carboxylate metalloligand was designed and three heteronuclear coordination polymers of the metalloligand and metal nodes Cu2+, Zn2+ and Cd2+ were prepared. X-ray single crystal analyses (CIF files CCDC nos. 1025722–1025724 for I–III) revealed that multiple favourable features endowed the metalloligand with a strong power to force the metal nodes to generate 1D helical coordination polymers. Thermogravimetric analyses showed that the complexes with Cu2+ and Zn2+ nodes exhibited moderate thermal stability. The three complexes were also characterized by IR spectra and PXRD.

Calix [4]-bis-monothiacrown-5 as a versatile building block for homo- and heterometallic coordination polymers

Exocoordination-based homonuclear and heteronuclear coordination polymers of calix [4]-bis-monothiacrown-5 (L) are reported. L reacts with HgCl2 and affords a one-dimensional (1D) coordination polymer [L(μ-Hg2Cl4)]n (1) linked by neutral square-type Hg2Cl4 clusters. A straightforward one-pot reaction of L with a mixture of HgCl2 and KCl resulted in the isolation of a heteronuclear species [(K2L)(μ-Hg3Cl8)]n (2) adopting a 1D polymeric structure in which the endocyclic dipotassium(I) complex cation units of L are linked by anionic open double-square type (μ-Hg3Cl8)2− clusters. Both products form a pseudo 3D framework via interchain H-bonds and their topological analyses were also carried out.

Synthesis, Crystal Structure and Magnetic Property of a New Three-Dimensional Mn–Na Heteronuclear Coordination Complex Based on 3,5-Pyrazoledicarboxylic Acid

A new three-dimensional Mn–Na heteronuclear coordination polymer based on 3,5-Pyrazoledicarboxylic acid (H3dcp) and NCS− as the co-ligands {Mn(Hdcp) [Na2(H2O)2](NCS)2}n(1) has been synthesized and structurally characterized by single-crystal X-ray diffraction analysis. The complex crystallizes in orthorhombic system, space group Cmca, with a = 16.4275(14), b = 18.4935(16), c = 11.0252(9) A, β = 90°, V = 3349.5(5) A3, Z = 8. Analysis of the crystal packing of the complex reveals that it has 1D Na–O chains in which the adjacent Na(I) ions are linked through two types of oxygen bridges afforded by carboxyl oxygen atoms of 3,5-Pyrazoledicarboxylic acid ligands and solvent water molecules. While the interconnection of Mn(II) ions by chelating and bridging μ3-Hdcp anions result in a 2D grids, which are further pillared by the 1D Na–O chain to generate a 3D polythreaded architecture with the Schlafli symbol of (43·63)2(43·67)(49·611·8). Furthermore, magnetic susceptibility measurements of this complex shows weak antiferromagnetic exchange between the manganese(II) ions (θ = −3.16 K).

PH-Dependent two novel heteronuclear Cu(II)/Sr(II) coordination polymers constructed from 1,3,5-benzenetricarboxylic acid: Synthesis, crystal structures and properties

Two novel heteronuclear coordination polymers, namely, [CuSr2(BTC)2]·10H2O (1) and [Cu2Sr(H4TMA)2]·4H2O (2) (H3BTC = 1,3,5-benzenetricarboxylic acid, H4TMA = 2-hydroxytrimesic acid) were hydrothermally synthesized as pH-dependent products and characterized by elemental analysis (EA), infrared spectroscopy (IR) and single crystal X-ray diffraction. For compound 1, it displays a 3D structure with (2,5,6)-connected net topology. For 2, the H3BTC ligand is oxidized into H4TMA and compound 2 features a 2D layer structure, which is further linked by Cu⋯Cu and Cu⋯O supramolecular interactions into a 3D structure. The results show that the pH plays a crucial role in determining the structure of the compounds. In addition, thermalgravimetric analysis of compounds 1–2 and luminescence property of 1 are also investigated.

Dual emission tunable in the near-infrared (NIR) and visible (VIS) spectral range by mix-LnMOF.

In this study, we describe the synthetic approach, crystallographic structure, luminescent behavior and elucidation of the channels of the energy conversion in heteronuclear coordination polymers with emission in the visible (Eu(3+) and organic ligand) and near-infrared (Nd(3+)) range. The [(Nd0.9Eu0.1)2(dipc)3(H2O)3]n·nH2O, [(Nd0.7Eu0.3)2(dipc)3(H2O)3]n·nH2O, [(Nd0.5Eu0.5)2(dipc)3(H2O)3]n·nH2O, [(Nd0.3Eu0.7)2(dipc)3(H2O)3]n·nH2O, [(Nd0.1Eu0.9)2(dipc)3(H2O)3]n·nH2O, [Eu2(dipc)3(H2O)3]n·nH2O and [Nd2(dipc)3(H2O)3]n·nH2O materials are obtained by hydrothermal conditions from pyridine-2,6-dicarboxylic acid (H2dipc) and Ln2O3 oxide (Ln = Eu and Nd). The fine structures in the emission spectrum and spectral profile are used to investigate the ion responsible for the emission characteristics of a material (6), based on coordination polyhedron. The heteronuclear systems show emission in the dual spectral range (NIR-VIS) tuned for blue or red. The tuning of emission on the red (Eu(3+)) or blue (organic ligand) range may be performed by controlling the stoichiometric ratio of the lanthanide ions and by controlling the excitation wavelength. Nd(3+) ions display self-absorption of emission to dipc ligand, resulting in interference on the emission band profile ranging from 400 to 600 nm. The energetic process of energy transfer is operated by a cascade of energy transfer, from dipc ligand mainly to Eu(3+) ions and finishing on the Nd(3+) ion. The efficient sensitization to Nd(3+) by Eu(3+) ions is due to the presence of many resonant energy levels and the short distance between these ions.

Preparation and luminescent properties of coordination polymers of terbium and europium with 1,4-bis-(4-methoxycarbonyl-3-hydroxyphenoxycarbonyl)butane

Physicochemical properties of new isostructural homo- and heteronuclear coordination polymers of terbium and europium with 1,4-bis-(4-methoxycarbonyl-3-hydroxyphenoxycarbonyl)butane (H2L) differing in the composition have been studied. The Tb2L3·H2O compound has exhibited efficient sensibilized green luminescence, whereas the corresponding europium-containing polymer EuL3·H2O has shown practically no luminescence due to mismatch of energies of the ligand triplet level and the Eu3+ ion emitting level. Heteronuclear terbium-europium polymers (Tb1.5Eu0.5L3·H2O, TbEuL3·H2O, and Tb0.5Eu1.5L3·H2O) show luminescence via the intramolecular transfer of the exiting energy from Tb3+ emitting level to Eu3+.

A novel 3D heterometallic coordination complex with (3,4,5)-connected net topology: Synthesis, structure and luminescent property

A novel three-dimensional Ag(I)–Pb(II) heteronuclear coordination polymer, namely [Ag2Pb2(BTC)2(H2O)2]n (1), where H3BTC=1,3,5-benzenetricarboxyl acid, has been hydrothermally synthesized and structurally characterized by elemental analysis(EA), infrared spectroscopy(IR) and single crystal X-ray diffraction. The BTC3− ligand exhibits an interesting coordination mode to form a three-dimensional (3D) framework with a novel hexa-nodal (3,4,5)-connected net topology. The thermal stability and solid state fluorescence of 1 have also been investigated.

Highly sensitized near-infrared luminescence in Ir–Ln heteronuclear coordination polymers via light-harvesting antenna of Ir(iii) unit

Four novel iridium–lanthanide heteronuclear coordination polymers {Ln[Ir(ppy)2(dcbpy)]2(OH)}·H2O (Ir–Ln; Ln = Gd, Yb, Er, Nd, ppy = 2-phenylpyridine, dcbpy = 2,2′-bipyridine-4,4′-dicarboxylate) were successfully obtained by hydrothermal reactions based on a Ir unit (Ir(ppy)2(Hdcbpy), L–H). In these complexes, the Ir unit acts as a good light-harvesting antenna showing high visible light absorption via triplet metal-to-ligand charge transfer (3MLCT), and effectively sensitizes Ln(III)-based near-infrared (NIR) luminescence by d → f energy transfer from the Ir unit to the Ln3+ ions. Those coordination polymers display the characteristic NIR emission of Ln(III) ions (Ln = Yb, Er, Nd) when being excited by 500 nm visible light, while the characteristic 3MLCT luminescence of the Ir unit was almost quenched. The Ir–Nd polymer exhibited the maximum quenching of the 3MLCT luminescence of the Ir unit because the Nd(III) ion is the most effective energy-acceptor with a high density of low-lying f–f states. The coordination polymer structures of Ir–Ln reduce the effect of high-energy oscillators (O–H, C–H) and further increase the Ln(III)-based emission lifetimes and quantum yields. The successfully acquired highly sensitized NIR luminescent Ir–Ln coordination polymers pave a new approach to the design and synthesis of NIR luminescent materials.

Synthesis, crystal structures, spectroscopic, thermal analysis, electrochemical and solution studies of two new mixed metal coordination polymers based on dipicolinic acid and 3,4-diaminopyridine

Two new 2D heteronuclear coordination polymers with Ni(II), Zn(II) and Ca(II), namely {(dapH)2[CaM2(pydc)4(H2O)2]·2H2O}n (M=Ni (1) and M=Zn (2)) where [pydcH2=pyridine-2,6-dicarboxylic acid (dipicolinic acid), dap=3,4-diaminopyridine] have been synthesized and characterized by elemental analysis, infrared spectroscopy, thermal (TG/DTG/DTA) analysis, electrochemical as well as X-ray single crystal diffraction. The compounds 1 and 2 display isostructural features and crystallized in the monoclinic P21/n space group. Both of the compounds contain cationic and anionic fragments and two uncoordinated water molecules. In 1 and 2 (pydc)2− acts as tridentate ligands and connected to calcium ions through carboxylate bridging. Then each dipicolinate ligand bridges one calcium to a M(II) atom.The equilibrium constants of the binary, ternary and quaternary complexes of ligands or proton transfer system with metal ions in an aqueous solution were investigated by a potentiometric pH titration method.

Tuning the catalytic activity of the heteronuclear coordination polymers [CoxZn1 − x(tdc)(bipy)] and [CoxZn1 − x(Me2trz–pba)2] in the epoxidation of cyclooctene via isomorphous substitution

For two series of isostructural, heteronuclear 3D coordination polymers containing Co and Zn, i.e., [CoxZn1−x(tdc)(bipy)] and [CoxZn1−x(Me2trz–pba)2], with nCo/nZn-ratios from 0.00 to 1.00, the epoxidation of cyclooctene with tert-butyl hydroperoxide in liquid toluene at 348K was studied. In dependence of the Co-content in the material, the catalytic activity steadily increases with the Co-free materials being inactive and the Zn-free materials showing the highest catalytic activity (cyclooctene conversion of 32% and epoxide selectivity of 50%). Although the catalytic conversion occurs at the outer crystallite surface, the results prove that a sensitive tuning of the catalytic properties of coordination polymers and metal-organic frameworks can be achieved by isomorphous substitution with redox active elements.

A three-dimensional Cu–Na heteronuclear coordination polymer based on iminodiacetic acid

A novel Cu-Na heteronuclear three-dimensional coordination polymer, poly[diaquadi-μ5-iminodiacetato-di-μ4-iminodiacetato-tricopper(II)disodium(I)], [Cu3Na2(C4H5NO4)4(H2O)2]n, has been prepared by hydrothermal synthesis. The asymmetric unit contains one and a half copper(II) cations, a sodium cation, two iminodiacetate (ida) ligands and a coordinated water ligand. One of the two independent Cu(II) centres is in a general position and is five-coordinated in a distorted square-pyramidal geometry. A [Cu(ida)] unit is formed via a bis-chelating ida ligand and the coordination sphere of the Cu(II) atom is completed by two O atoms of two different neighbouring [Cu(ida)2] units. These [Cu(ida)2] units are associated with the second Cu(II) cation, which is located on a crystallographic inversion centre and is coordinated in a distorted square-planar geometry by two chelating ida ligands. The carboxylate groups of the ida ligands act as bridges and connect the [Cu(ida)] and [Cu(ida)2] building blocks in a 2:1 ratio, forming two-dimensional arrays. These layers are interconnected into a three-dimensional structure by the sodium ions. Each Na(I) cation is coordinated by six O atoms from five ida ligands and a water molecule. When [Cu(ida)], the Na(I) cations and [Cu(ida)2] are viewed as 5-, 5- and 8-connected nodes, respectively, the three-dimensional network exhibits a (3(2).4(3).5(2).6(3))2(3(2).4(3).5(2).6(3))2(3(4).6(16).7(8)) topology.

Coordination polymers based on 1,1′-cobaltocenium dicarboxylate linkers

With 1,1′-cobaltocenium dicarboxylate as a cobalt-containing linker, heteronuclear coordination polymers 2∞[M(ccdc)2] (M2+ = Zn2+, Cd2+, Cu2+; ccdc− = 1,1′-cobaltocenium dicarboxylate) are generated. These compounds exhibit symmetry related structures with their structural details depending on the preferred coordination sphere of the respective metal ion. The structural relationships between these two-dimensional coordination polymers and the dependence on type and quantity of cocrystallized solvent molecules are discussed in this article. In the presence of 4,4′-bipyridine (bipy) as a co-linker, metal acetates and Hccdc/(H2ccdc)PF6 form the three-dimensional framework 3∞[Zn(ccdc)(bipy)]PF6 and the two-dimensional networks 2∞[Zn(ccdc)(bipy)]PF6 and 2∞[Cu(ccdc)(bipy)]PF6.

Synthesis, crystal structure and luminescent properties of new lanthanide-containing coordination polymers involving 4,4′-oxy-bis-benzoate as ligand

Reactions in water between the disodium salt of 4,4′-oxy-bis-benzoic acid (H2oba) and lanthanide chlorides lead to three families of coordination polymers with respective general chemical formulae [Ln2(oba)3(H2O)5·H2O]∞ with Ln = La–Nd (Family 1), [Ln2(oba)3(H2O)6·3H2O]∞ with Ln = Sm–Ho or Y (Family 2) and [Ln2(oba)3(H2O)5.5·0.5H2O]∞ with Ln = Sm–Dy (Family 3). Compounds that belong to Family 1 are isostructural. The crystal structure has been solved on the basis of the La-containing compound. This compound crystallizes in the monoclinic system, space group P2/n (no. 13) with a = 23.622(4) A, b = 6.066(1) A, c = 29.414(6) A, β = 102.034(7)°, V = 4129.0(13) A3 and Z = 4. Compounds that belong to Family 2 are isostructural. The crystal structure has been solved on the Gd-containing compound. This compound crystallizes in the monoclinic system, space group P2/a (no. 14) with a = 9.9474(1) A, b = 15.6416(2) A, c = 28.7511(4) A, β = 95.117(1)°, V = 4455.65(10) A3 and Z = 4. Compounds that belong to Family 3 are isostructural. The crystal structure has been solved on the Gd-containing compound. This compound crystallizes in the monoclinic system, space group C2/c (no. 15) with a = 59.6523(11) A, b = 8.2064(1) A, c = 16.9558(2) A, β = 95.447(1)°, V = 8262.9(2) A3 and Z = 4. The three crystal structures are three-dimensional and rather compact. Their potential porosities are rather low. They have been estimated as 95 m2 g−1, 113 m2 g−1, and 36 m2 g−1 respectively. The luminescent properties under UV irradiation of these compounds have been explored. In particular, quantum yields, lifetimes and colorimetric coordinates of the Tb- and the Eu-containing coordination polymers have been determined. A heteronuclear coordination polymer with chemical formula [EuTb(oba)3(H2O)5.5·0.5H2O]∞ has been synthesized and characterized. It belongs to the structural family 3. Its luminescent properties have been explored in detail in order to better understand the energy transfer mechanisms and to evaluate the tunability of these families of compounds.

Synthesis, crystal structure, and characterizations of a (6,3)-connected coordination polymer based on cadmium(II) and nickel(II)

A novel heteronuclear coordination polymer Cd(1,3-μ-SCN)6Ni2(C2H8N2)2(H2O)2 (I) has been prepared and characterized by elemental analysis, EDS analysis, PXRD and IR spectrum and single-crystal X-ray diffraction. The single-crystal X-ray diffraction analysis revealed that compound I crystallizes in a monoclinic system of space group C2/m with a = 19.427(8), b = 9.622(3), c = 7.261(3) A, β = 105.383(10)°. The compound exhibits a (6,3)-connected two-dimensional layer which is built up from the strict alternation of 6-connected {CdS6} octahedra and 3-connected {NiON5} octahedra.

Rational Design and Synthesis of a New Organometallic Ligand, 1-Ferrocenyl-3-(5-bromopyridyl)-prop-3-enol-1-one and Its Heteronuclear Coordination Polymer, {Cu[1-ferrocenyl-3-(5-bromopyridyl)prop-1,3-dionate]2}n

A new bifunctional organometallic ligand was synthesized, by reacting ferroceneacyl anion with ethyl-5-bromonicotinic acid, isolated, and characterized as 1-ferrocenyl-3-(5-bromopyridyl)-prop-3-enol-1-one (HL1). This new ligand reacts with Cu(II) salt to yield a new two-dimensional (2D) heteronuclear (Fe–Cu) coordination polymer of type [Cu(L1)2]n. Single crystal X-ray diffraction analysis of both the ligand and the coordination polymer is provided in this report.