Heteroleptic zinc dipyrromethene complexes

¹H NMR spectroscopy has been used to study the complexation of a per‐alkyl dipyrromethene with zinc acetate. An intermediate, assigned to be the heteroleptic Zn(dipyrromethene)(acetate) complex, is observed under titration conditions although only zinc(dipyrromethene)₂ is obtained after simple work‐up. This indicates that disproportionation occurs during work‐up and that dipyrromethene complexation does not occur under self‐assembled control.     

Yttrium-succinates coordination polymers: Hydrothermal synthesis, crystal structure and thermal decomposition

New polymeric yttrium-succinates, Y₂(C₄H₄O₄)₃(H₂O)₄·6H₂O and Y₂(C₄H₄O₄)₃(H₂O)₂, have been synthesized, and their structures (solved by single crystal XRD) are compared with that of Y₂(C₄H₄O₄)₃(H₂O)₂·H₂O. Three compounds were obtained as single phases, and their thermal behaviour is described.     

Heteroleptic Cu(II) dipyrromethene complexes linked via hydrogen bonds, coordinative bonds, and covalent bonds: probing the coordination environment by electron paramagnetic resonance spectroscopy

meso-Phenyldipyrromethene acetylacetonato copper(II) complexes [Cu(dpm-C6H4R)(acac)] (dpm-C6H4R = phenyl-substituted dipyrromethene, acac = acetylacetonato) with different substituents R at the phenyl moiety were synthesized. These substituents determine the mode of assembly into polymeric chains, namely, via hydrogen bonds, coordinative bonds, or covalent bonds (by immobilization on a polymer). Although the primary coordination sphere around the copper center is essentially identical for all complexes reported in this study (square-planar geometry with N2O2 coordination), subtle differences due to the different microenvironments have been observed in their structures, properties, and reactivity as probed by IR spectroscopy, electron paramagnetic resonance spectroscopy, magnetic measurements, thermal analyses, density functional theory calculations, and reaction with pyridine.     

Two 1-D europium coordination polymers: synthesis,crystal structure and fluorescence

Two new complexes {[Eu(2, 4-DFBA)₃ · (H₂O)₂] · H₂O} _n (1) and [Eu(2-BrBA)₃ · H₂O] _n (2) (2, 4-DFBA = 2, 4-difluorobenzoate, 2-BrBA = 2-bromobenzoate) have been synthesized and characterized by single crystal X-ray diffraction. 1 has a 1-D chain structure, in which Eu(III) ions are bridged by single COO^? groups and a 2-D supramolecular network is formed by hydrogen bond interactions. In 1, each Eu(III) is eight-coordinate with six oxygens from four 2,4-DFBA ligands and two waters. 2 has a 1-D chain structure, in which Eu(III) ions are bridged by bridging-chelating-bridging COO^? groups. In 2, each Eu(III) ion is nine-coordinate with eight oxygens from five 2-BrBA ligands and one water. The two complexes exhibit intense luminescence at room temperature. The ⁵D₀ → ⁷F _j (j = 0–4) transition emissions of Eu(III) have been observed.     

Heteroleptic copper(I) complexes coupled with methano[60]fullerene: synthesis, electrochemistry, and photophysics

Heteroleptic copper(I) complexes CuPOP-F and CuFc-F have been prepared from a fullerene-substituted phenanthroline ligand and bis[2-(diphenylphosphino)phenyl] ether (POP) and 1,1'-bis(diphenylphosphino)ferrocene (dppFc), respectively. Electrochemical studies indicate that some ground-state electronic interaction between the fullerene subunit and the metal-complexed moiety are present in both CuPOP-F and CuFc-F. Their photophysical properties have been investigated by steady state and time-resolved UV-vis-NIR luminescence spectroscopy and nanosecond laser flash photolysis in a CH2Cl2 solution and compared to those of the corresponding model copper(I) complexes CuPOP and CuFc and of the fullerene model compound F. Selective excitation of the methanofullerene moiety in CuPOP-F results in regular deactivation of the lowest singlet and triplet states, indicating no intercomponent interactions. Conversely, excitation of the copper(I)-complexed unit (405 nm, 40% selectivity) shows that the strongly luminescent triplet metal-to-ligand charge-transfer ((3)MLCT) excited state located at 2.40 eV is quenched by the carbon sphere with a rate constant of 1.6 x 10(8) s(-1). Details on the mechanism of photodynamic processes in CuPOP-F via transient absorption are hampered by the rather unfavorable partition of light excitation between the two chromophores. By determination of the yield of formation of the lowest fullerene triplet level through sensitized singlet oxygen luminescence in the NIR region, it is shown that the final sink of photoinduced processes is always the fullerene triplet. This can be populated via a two-step charge-separation charge-recombination process and a less favored (3)MLCT --> (3)C60 triplet-triplet energy-transfer pathway. In CuFc-F, both of the photoexcited copper(I)-complexed and fullerene moieties are quenched by the presence of the ferrocene unit, most likely via ultrafast energy transfer.     

Hydrogen bonding and multiphonon structure in copper pyrazine coordination polymers

We report a systematic investigation of the temperature-dependent infrared vibrational spectra of a family of chemically related coordination polymer magnets based upon bridging bifluoride (HF(2)-) and terminal fluoride (F-) ligands in copper pyrazine complexes including Cu(HF(2))(pyz)(2)BF(4), Cu(HF(2))(pyz)(2)ClO(4), and CuF(2)(H(2)O)(2)(pyz). We compare our results with several one- and two-dimensional prototype materials including Cu(pyz)(NO(3))(2) and Cu(pyz)(2)(ClO(4))(2). Unusual low-temperature hydrogen bonding, local structural transitions associated with stronger low-temperature hydrogen bonding, and striking multiphonon effects that derive from coupling of an infrared-active fundamental with strong Raman-active modes of the pyrazine building-block molecule are observed. On the basis of the spectroscopic evidence, these interactions are ubiquitous to this family of coordination polymers and may work to stabilize long-range magnetic ordering at low temperature. Similar interactions are likely to be present in other molecule-based magnets.     

Coordination polymer gels: synthesis, structure and mechanical properties of amorphous coordination polymers

The synthesis and mechanical properties of a new class of coordination polymer based materials, amorphous coordination polymer sol-gels and xerogels, is presented.     

Heterotrimetallic 4f-3d coordination polymers: synthesis, crystal structure, and magnetic properties

A series of cyano-bridged heterotrimetallic complexes [CuL](2)Ln(H(2)O)(2)M(CN)(6).7H(2)O have been synthesized by the reactions of CuL (L(2)(-) = dianion of 1,4,8,11-tetraazacyclotradecane-2,3-dione), Ln(3+) (Ln = Gd or La), and [M(CN)(6)](3)(-) (M = Co, Fe, or Cr). X-ray diffraction analysis reveals that these complexes are isostructural and have a novel chain structure. The Ln(3+) ion is eight-coordinated by six oxygen atoms of two CuL and two water molecules and two nitrogen atoms of the bridging cyano ligands of two [M(CN)(6)](3)(-), while the [M(CN)(6)](3)(-) anion connects two Ln(3+) using two trans-CN(-) ligands giving rise to a chainlike structure. In the chain, every CuL group tilts toward the CN(-) ligand of adjacent [M(CN)(6)](3)(-) with the Cu-N(cyano) contacts ranging from 2.864(6) to 2.930(6) A. Magnetic studies on the CuGdCo complex (1) indicate the presence of ferromagnetic coupling between Cu(II) and Gd(III). The CuLaCr (5) and CuLaFe (2) complexes exhibit ferromagnetic interaction between paramagnetic Cu(II) and Cr(III)/Fe(III) ions through the weak cyano bridges (Cu-N(cyano) = 2.930(6) A for 2). A global ferromagnetic interaction is operative in the CuGdFe complex (3) with the concurrence of dominant ferromagnetic Cu(II)-Gd(III) and minor antiferromagnetic Gd(III)-Fe(III) as well as the ferromagnetic Cu(II)-Fe(III) interaction. For the CuGdCr complex (4), an overall antiferromagnetic behavior was observed, which is attributed to the presence of dominant antiferromagnetic Cr(III)-Gd(III) coupling and the minor ferromagnetic Cu(II)-Gd(III) and Cu(II)-Cr(III) interaction. Moreover, a spin frustration phenomenon was found in complex 4, which results from the ferro-ferro-antiferromagnetic exchanges in the trigonal Cu-Gd-Cr units. The magnetic susceptibilities of these complexes were simulated using suitable models. The magneto-structural correlation was investigated. These complexes did not show a magnetic phase transition down to 1.8 K.     

Two one-dimension copper(II) coordination polymers based on imine-based bidentate Schiff-base ligand: synthesis, crystal structure and luminescent properties

Two new one-dimension copper(II) coordination polymers [CuL(2)(NCS)(2)](n) (1) and [CuL(2)(NO(3))(2)](n) (2) (L=(C(5)H(4)N)C(CH(3))=N-N=(CH(3))C(C(5)H(4)N)) have been synthesized and characterized by IR, elemental analysis, TG technique and X-ray crystallography. Each Cu(II) atom has a distorted octahedral N(6) (1) or N(4)O(2) (2) environment with four pyridyl N atoms from four ligands and two N atoms from two NCS(-) anions for polymer 1 or two O atoms from two NO(3)(-) anions for polymer 2, respectively. A pair of bis-monodentate bridging ligands links two Cu(II) centers to form one dimension chain structure containing bimetallic 22-membered macrometallacyclic rings. 1D chain is held together with its neighboring ones via C-H?S hydrogen bonds for 1 and C-H?O hydrogen bonds, C-H?π interactions for 2 to form a 3D supramolecular structure, respectively. The luminescent properties of the polymers 1 and 2 were investigated in the solid state at room temperature.     

From coordination complexes to coordination polymers through self-assembly

Metal ion coordination in metallo-supramolecular assemblies offers the opportunity to fabricate and study devices and materials that are equally important for fundamental research and new technologies. Metal ions embedded in a specific ligand field offer diverse thermodynamic, kinetic, chemical, physical and structural properties that make these systems promising candidates for active components in functional materials. In particular, dynamic coordination polymers offer exciting opportunities to provide materials with responsive properties. In addition, this approach allows to incorporate the well known properties of metal complexes in polymeric architectures. This review highlights the improvements and the possible applications based on metallo-supramolecular systems with an emphasis on materials science. Examples for new materials such as molecular magnets, coordination polymers as carrier package as well as molecular electronics are featured in this article.     

2-D coordination polymers of copper and cobalt with 3,4-pyridinedicarboxylic acid: synthesis,characterization, and crystal structures

Two new complexes involving 3,4-pyridinedicarboxylic acid (3,4-H₂pdc), copper(II) and cobalt(II) complexes, {[Cu(3,4-Hpdc)₂(H₂O)₂]·2dmso}_n (1) and {[Co(3,4-Hpdc)₂(H₂O)₂]·2H₂O·2dmso}_n (2) (dmso = dimethylsulfoxide), have been synthesized by the diffusion method and characterized by elemental analysis, IR spectroscopy, thermal analysis, powder and single-crystal X-ray diffraction analysis, and electron paramagnetic resonance (EPR). In both compounds, the metal coordination sphere is composed of a trans-MO₄N₂ core and adopts a distorted octahedral geometry in accordance with X-ray diffraction and EPR results. 3,4-Hpdc^? ligands bridge the metal centers giving two-dimensional (2-D) coordination polymers with four-connected uninodal nets of (4,4) topology.     

Construction of highly oriented crystalline surface coordination polymers composed of copper dithiooxamide complexes

Layer-by-layer bottom-up crystal engineering of metal-organic crystals at the surface of sapphire or glass from organic (rubeanic acid and derivatives) and inorganic (Cu(2+)) components which when mixed in solution form instantly an amorphous solid with high proton conduction.     

Two lead coordination polymers with nitrilotriacetic acid and oxydiacetic acid: synthesis,characterization, and crystal structure

Two lead coordination compounds [Pb₂(nta)]NO₃ (1) and [Pb(oda)] (2) have been synthesized by slow evaporation or hydrothermal conditions using nitrilotriacetic acid (nta) and 2,2′-oxydiacetic acid (oda) as ligands, respectively. Their structures were determined by single-crystal X-ray diffraction and further characterized by X-ray powder diffraction, infrared absorption spectrum, and thermogravimetric analysis. Compound 1 is a 2-D honeycomb-like layer structure with (6,3) topology. When the bonding limit of Pb–O extends from 2.76 to 2.90 Å, potential weak Pb–O bonds can be found in 1, and the 2-D layer structure can be further linked to generate a 3-D 4-connected supramolecular sra net with the (4².6³.8) Schläfli symbol. Compound 2 contains a 1-D infinite Pb–O chain which is connected through µ₃-, µ₄-, and µ₅-coordination modes of oda to form a new 3-D structure.     

Synthesis, structure and application of chiral copper(II) coordination polymers for asymmetric acylation

Chiral copper(II) coordination polymers 1a-c have been prepared by one-pot synthesis in high yield. Their single-crystal X-ray analysis showed that repeating units are connected to each other by carboxylate linker and copper(II) atoms are pentacoordinated with distorted square-pyramidal geometry for 1a-b and square-planar geometry for 1c. These polymers have catalyzed the kinetic resolution of secondary alcohols by acylation with up to 90% ee ( s = 50).     

Amidoxime polymers - copper complexes

The aminolysis of nitrile groups in macroporous acrylonitrile-divinylbenzene copolymers leads to amphoteric ion exchange resins with 1.0 - 3.3 mmol/g amidoxime groups content. The starting copolymers were synthesized from the same monomer mixture, but the composition of diluents used were different. The resulting polymers with amidoxime groups have different sorption of Cu(II) ions, the highest values between 1.3 and 3.5 mmol/g at pH 5. EPR and IR spectra were used to indicate the formation of the complexes between Cu(II) ions and amidoxime polymers. On the basis of the EPR parameters structure of complexes formed at different pH and Cu(II) concentration was postulated.     

Design,synthesis and structural diversity in coordination polymers

The fundamental precept of crystal engineering is that all the information necessary for the design of a network is already stored in the molecular building blocks used. Coordination polymers represent an example of how crystal engineering has become a paradigm for the synthesis of new architectures and compositions. We report herein ten structures that are supramolecular isomers of one another. The structures are prepared from the same building blocks under mild reaction conditions. The modularity of coordination polymers imparts structural diversity that otherwise would not be possible.     

Helical coordination polymers and cyclic dimers formed from heteroleptic thioether-dipyrrinato copper(II) complexes

Heteroleptic copper complexes containing an acetylacetonato ligand and a thioether derivatized dipyrrinato ligand are shown to form oligomers and polymers in the solid state.