Two-dimensional Coordination Polymer Research Articles

The joint effect of elasticity, interaction energy and entropy on behavior of pressure- and temperature-induced electronic bistability in a family of two-dimensional Hofman-like coordination polymers

Based on two-dimensional Hofmann-type compounds, we systematically studied the regulation of the spin state by pressure combining theory and experiments. The ways of controlling the spin state under pressure have been installed.

2D/3D spin crossover porous coordination polymers based on isomeric tetrapyridyl benzene ligands

Topology and guest-dependent spin crossover behaviors are revealed in three-dimensional and two-dimensional porous coordination polymers based on the isomeric tetrapyridyl benzene ligands.

Single crystal-to-single crystal transformation - from two distinct to three distinct spin crossover centers in 2D coordination polymer [Fe(bbtr)3](CF3SO3)2.

1,4-Di(1,2,3-triazol-1-yl)butane (bbtr) forms a two-dimensional (2D) coordination polymer (1) in a reaction with iron(II) triflate. In the crystal lattice there are two crystallographically unique iron(II) ions surrounded octahedrally by a 1,2,3-triazole ring coordinated through nitrogen atoms N3. Single crystal X-ray diffraction studies revealed that spin crossover for each crystallographically independent iron(II) ion proceeds at a different temperature (T1/2(Fe1) = 201 K; T1/2(Fe2) = 216 K), while the magnetic measurements showed that there is one step, complete thermally induced spin crossover (T1/2 = 205 K). Complex 1 undergoes, with time, single crystal-to-single crystal transformation (SCSC) to the converted system (1c) from the R3̄ to the P63 space group, accompanied by significant changes in the lattice parameter c (a shortening of approximately one-third) and consequently unit cell volume. Structural transformation is associated with rebuilding of the polymeric layer as well as the anion network, which is reflected in the results of Mössbauer studies. In the polymorphic system (1c) there are three crystallographically independent iron(II) ions. The temperature dependence results for magnetic susceptibility indicated complete, one-step spin crossover very similar to that of 1; however, single-crystal X-ray diffraction studies of 1c revealed that spin crossover for each crystallographically independent iron(II) ion occurs in a different manner, revealing three elementary stages (T1/2(Fe1) = 200 K; T1/2(Fe2) = 212 K, T1/2(Fe3) = 214 K).

Solvatochromism and the effect of solvent on properties in a two-dimensional coordination polymer of cobalt-trimesate

A 2D coordination polymer can exchange guest species from liquid sorption, with accompanying visible colour changes.

Introducing Benzene-1,3,5-tri(dithiocarboxylate) as a Multidentate Linker in Coordination Chemistry.

Benzene-1,3,5-tri(dithiocarboxylate) (BTDTC3-), the sulfur-donor analogue of trimesate (BTC3-, benzene-1,3,5-tricarboxylate), is introduced, and its potential as a multidentate, electronically bridging ligand in coordination chemistry is evaluated. For this, the sodium salt Na3BTDTC has been synthesized, characterized, and compared with the sodium salt of the related ditopic benzene-1,4-di(dithiocarboxylate) (Na2BDDTC). Single-crystal X-ray diffraction of the respective tetrahydrofuran (THF) solvates reveals that such multitopic aromatic dithiocarboxylate linkers can form both discrete metal complexes (Na3BTDTC·9THF) and (two-dimensional) coordination polymers (Na2BDDTC·4THF). Additionally, the versatile coordination behavior of the novel BTDTC3- ligand is demonstrated by successful synthesis and characterization of trinuclear Cu(I) and hexanuclear Mo(II)2 paddlewheel complexes. The electronic structure and molecular orbitals of both dithiocarboxylate ligands as well as their carboxylate counterparts are investigated by density functional theory computational methods. Electrochemical investigations suggest that BTDTC3- enables electronic communication between the coordinated metal ions, rendering it a promising tritopic linker for functional coordination polymers.

Emerging Two-Dimensional Covalent and Coordination Polymers for Stable Lithium Metal Batteries: From Liquid to Solid.

Lithium metal anodes (LMAs) have attracted much attention in recent years because of their high theoretical capacity (3860 mAh g-1) and low electrochemical potential (-3.040 V vs standard hydrogen electrode). Lithium metal can be coupled with various cathodes to construct high-energy-density lithium metal batteries (LMBs) which hold great promise for next-generation batteries. However, the unstable solid electrolyte interphases (SEIs) and the uncontrollable lithium dendrite growth severely hinder the commercial development of LMAs. The emerging 2D polymers (2DPs), which possess high mechanical flexibility, high specific surface area, abundant surface chemistry, and rich chemical modification characteristics, have shown great advantages in addressing the inherent issues of LMAs. Herein, the current progress of 2DPs for stable and dendrite-free LMAs in liquid- and solid-based batteries is comprehensively reviewed. Some perspectives for the application of 2DPs in LMBs are also discussed. It is believed that the emerging 2DPs will provide insights into developing high-energy-density LMBs and beyond.

Two-dimensional zinc(II) and copper(I) coordination polymers for photoluminescence

Two-dimensional (2-D) coordination polymers [Zn2(bpab)(CH3CO2)4]·H2O (1), [Zn(bpab)(H2O)2](NO3)2 (2), [Cu2(bpab)I2]·CH3OH (3), and [Cu2(tpmd)I2] (4) have been synthesized by the reaction of zinc(II)/copper(I) ions and tetradentate polypyridine ligands (bpab = bis-1,4-(di-4-pyridylaminomethyl)benzene and tpmd = N,N,N',N'-tetrakis(pyridine-4-yl)methanediamine). The zinc(II) ions of 1 and 2 have distorted tetrahedral and trigonal bipyramidal geometries, respectively. By coordinating zinc(II) ions and bpab ligands, 1 and 2 formed a brick wall and puckered 2-D networks, respectively. The copper(I) ions of 3 and 4 are both tetrahedral structures with Cu2I2 rhomboidal geometry. By linking the Cu2I2 cores and bpab/tpmd ligands, 3 and 4 exhibited interwoven and interconnected bilayered 2-D networks, respectively. Compared to free bpab and tpmd ligands, polymers 1 and 2 show strongly blue-shifted emissions, whereas polymers 3 and 4 show strongly red-shifted emissions. Therefore, the shifts of emission wavelengths are strongly dependent on the zinc(II) and copper(I) ions that linked the bpab/tpmd tetradentate ligands, respectively.

Two-dimensional coordination polymer formed due to the unusual coordination of C[dbnd]O group in bis-dioxolene manganese complex

Ditopic ligand − 4,7-di(tert-butyl)-5,6-dihydro-1,3-benzodithiole-2,5,6-trione (o-quinone having fused 1,3-dithiolene-2-one cycle (-S-(CO)-S-) in back position) interacts with Mn2(CO)10 in toluene forming 2D-coordination polymer which layers are subdivided by the solvent molecules. Each manganese atom has six coordination environment which consists of square planar bis-dioxolene fragment and additional axial coordination is provided by two oxygen atoms of CO group of -S-(CO)-S- five-membered cycle from adjacent bis-dioxolene manganese fragment. Four bis-dioxolene manganese fragments form cycle which is the unit cell of 2D-polymer. Weak coordination of CO group with manganese atom can be simply destroyed. Re-crystallization of complex from tetrahydrofuran leads to the decomposition of the 2D structure and results in octahedral mononuclear (THF)2Mn(semiquinone)(catecholate) complex.

A two-dimensional framework with U-shaped Cu4I4 Cluster linked by semi-rigid ligand: Synthesis, crystal structure and Luminescent Properties

A new two-dimensional coordination polymer with formula of Cu4I4(3-bpcd)2·C2H5OH·1.5CH3CN (1) (3-bpcd=N,N'-bis(pyridin-3-yl) cyclohexane-1,4-dicarboxamide), has been synthesized at room temperature and structurally characterized. Crystallography study shows that 1 contains Cu4I4 clusters, which geometry significantly different from reported those called “cubane”, “stairstep” and “fliggy octahedron”. The Cu4I4 clusters in the structure of 1 were connected by semi-rigid ligand (3-bpcd) to form a two dimensional layer (4, 4) net, while Cu4I4 clusters are regarded as 4-connected nodes. These layers further stack in an ABAB fashion and each layer connect by hydrogen bond to generate a three dimensional framework. Thermogravimetric analysis reveals that 1 processes high thermal stability up to about 320 °C. Powder X-ray diffraction analysis indicates that the framework of structure of 1 could be stable in water/ethanol. The luminescent properties study of 1 show that the fluorescence intensity decreased with increase of the concentration of metal ions. Further study indicated that 1 could be used as a fluorescent probe and has high selectively effect on Fe(III) ions in ethanol, as well as in water. [Display omitted]

Structure and photoluminescence of two-dimensional lanthanide coordination polymers of mixed phthalate and azobenzene dicarboxylate

A new series of two-dimensional [LnIII(abdc)0.5(phth)(H2O)2]·2H2O coordination frameworks, where LnIII = EuIII (I), GdIII (II), TbIII (III), abdc2− = trans-azobenzene-4,4ʹ-dicarboxylate, and phth2− = phthalate, were designed, synthesized and characterized. According to the single crystal data and powder X-ray diffraction, I–III are isostructural and composed of the two-dimensional [LnIII(abdc)0.5(phth)(H2O)2] layers built up of the one-dimensional [LnIII(phth)(H2O)2] ladders and abdc2− linkers. Similarity in layer registry and identical topology to the other coordination polymers of phth2− are presented, from which the successful implementation of reticular concept is illustrated. Correlation between the framework structures and thermal stability as well as the N2 and CO2 sorption/desorption behaviors are included. Solid state photoluminescence of I–III were then investigated manifesting the substantial influence of abdc2− on the completely silent emission of I–III through the phth2−-to-abdc2− energy transfer.

A new two-dimensional folding sheet-like coordination polymer assembled from cadmium(II) and (S)-2-(benzylamino)succinic acid: synthesis, structure and properties.

A new two-dimensional (2D) coordination polymer, namely, poly[[diaqua[μ3-(S)-2-(benzylamino)succinato-κ4N,O1:O1':O4]cadmium(II)] monohydrate], {[Cd(C11H11NO4)(H2O)2]·H2O}n, has been synthesized by the solvothermal reaction of Cd(CH3COO)2·2H2O with the synthesized ligand (S)-2-(benzylamino)succinic acid (H2L). The title compound has been structurally characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction analysis. In the crystal structure, each CdII cation binds to three carboxylate groups from three symmetry-related L2- dianions. The tetradentate L2- ligand links three symmetry-related CdII cations into a 2D folding sheet, which can be simplified as a uninodal (3,3)-connected hcb net with the point symbol (63). In the lattice, all the folding sheets are arranged in an interdigitated fashion and aggregate into zipper-like arrays through interlayer π-π interactions. The large and nonpolar side chain may play an important role in the formation and aggregation of the 2D sheet. The thermal stability and photoluminescence properties of the title compound were investigated, and it exhibits a blue emission with a quantum yield of 8%.

A two-dimensional calcium (II) coordination polymer constructed from 2,2'-[terephthaloylbis(azanediyl)]diacetate: synthesis, structure and properties.

A new two-dimensional (2D) coordination polymer, namely, poly[[diaqua-[μ4-2,2'-[terephthaloylbis(azanediyl)]diacetato]calcium(II)] monohydrate], {[Ca(C12H10N2O6)(H2O)2]·H2O}n, (I), has been synthesized by the reaction of CaCl2 with 2,2'-[terephthaloylbis(azanediyl)]diacetic acid (H2L). The title compound was structurally characterized by single-crystal X-ray diffraction analysis, elemental analysis and IR spectroscopy. In the crystal structure of (I), each CaII cation binds to six carboxylate groups from four symmetry-related L2- dianions. The hexadentate L2- ligand links four symmetry-related calcium cations into a 2D layer-like structure, which can be simplified as a uninodal SP 2-periodic (3,6)III net with the point symbol (43·63). In the lattice, all layers pack in parallel arrays through weak interlayer hydrogen bonding and π-π interactions. The thermal stability and photoluminescence properties of (I) have been investigated. Thermogravimetric analysis reveals the different thermal stabilities of the two coordinated water molecules due to their different hydrogen-bonding interactions. The title coordination polymer exhibits an excitation-wavelength-dependent fluorescence in the solid state.

A two-dimensional manganese coordination polymer: Crystal structure, proton conductivity and catalytic property

Herein, we report a new Manganese coordination polymer, Mn3L2(H2O)4·2H2O (1), based on the 4′-(1-H-tetrazol-5-yl)-[1,1′-biphenyl]-3,5-dicarboxylic acid (H3L) ligand under solvothermal condition. 1 shows a two-dimensional layer structure and has strong interaction with the guest water molecules by the Hydrogen-bond network. Moreover, 1 exhibits good proton conductivity with a value of 1.59 × 10−5 S cm−1 under 98% RH at 75 °C. The proton conduction mechanism can be viewed as vehicle mechanism due to the lattice water in the structure of 1. In addition, after removed the water molecules, the open metal sites at the metal nodes of 1 can be used as Lewis acidic active sites and used as heterogeneous catalyst for the cyanosilylation reaction with good reactivity. We anticipate this work can encourage the investigation of the properties of the coordination polymers assembled by tetrazole derivative ligands.

Selective ethylene oligomerization based on Fe-containing metal-organic coordination polymer catalysts

One-dimensional, two-dimensional and three-dimensional Fe-containing metal-organic coordination polymer (1D/2D/3D-Fe-MOCP) catalysts have been solvothermally synthesized and evacuated at different temperatures to give a series of 1D-Fe, 2D-Fe and 3D-Fe catalysts used for ethylene oligomerization performed in slurry batch mode. Their catalytic performances were investigated with the aid of AlEt2Cl cocatalyst, and moderate catalytic activities and high selectivities to low carbon olefins C4, C6, C8, and C10 were observed. Moreover, the oligomerization product distributions differed depending on various factors such as the structural dimension, ligand type, framework flexibility, distances between metal atoms, et al. 1D-Fe catalyst evacuated at 150 °C for 8 hours showed high C8 olefin selectivity up to 94.90% with the catalytic activity of 6.28 × 105 g/mol(Fe)•h•atm. However, 2D-Fe and 3D-Fe catalysts showed relatively low catalytic activity and low selectivity for C8 olefin.

Two 2D Co(II)/Mn(II) coordination polymers based on the quinoline-2,3-dicarboxylate ligand: synthesis, crystal structure, and fluorescence properties

Abstract A pair of two-dimensional (2D) isostructural coordination polymers (CPs), {[Co(2,3-qldc)(H2O)]} n (1) and {[Mn(2,3-qldc)(H2O)]} n (2), where 2,3-H2qldc = quinoline-2,3-dicarboxylic acid, were hydrothermally synthesized and characterized through IR spectroscopy, elemental and thermal analysis, power X-ray diffraction, and single-crystal X-ray diffraction. The results have revealed that the fully deprotonated 2,3-H2qldc ligand connects the Co(II)/Mn(II) atoms with a μ 3-bridge to form a square-wave 2D network, which is further extended into 3D stacks through O–H···O, C–H···O hydrogen bonds and π···π stacking interactions. Topologically, 1 or 2 can be simplified as a 4-connected sql type with a Schläfli symbol {44·62} and a Shubnikov tetragonal plane net, or as a 3-connected fes type with a Schläfli symbol {4·82} and a Shubnikov plane net. The thermal stability and the solid state fluorescence properties of 1 and 2 were investigated.

Two-dimensional coordination polymers containing permethylated motifs - promising candidates for 2D emerging materials. Structural, behavioral and functional particularities

Although three-dimensional metal-organic frameworks (3D MOFs) currently enjoy great attention in the scientific world due to their utility to address challenges concerning energy, environment cleaning and not only, very recently two-dimensional version of these, rather considered two-dimensional coordination polymers (2D CPs), have become of interest from the perspective of their approach as ultra-thin layered 2D materials. Different from the emerging 2D materials that are generally inorganic in nature (graphene or 2D allotropes of various elements, MXenes, etc.), 2D CPs contain both inorganic and organic blocks, offering wider possibilities for structural diversification and area of applicability. However, in the crystallization process, 2D CP layers often stack on the basis of intermolecular interactions, leading to higher dimensional materials, which limit the manifestation of the size-effect properties. Their isolation individually or in multilayers with thickness/surface aspect ratio as small as possible is a challenge that seeks solutions through top-down or bottom-up approaches, each of them having certain limits. An original pathway consists in the use of a permethylated ligand with lower surface energy which, through its orientation in the coordination process to the metal ion, favors the anisotropic growth of the polymer and ensures the shielding of the formed nanosheet structure preventing the establishment of noticeable interlayer interactions. Such unique two-dimensional coordination polymers recently reported by the authors and some new data about them are reviewed here from the perspective of their structural particularities, properties, reactivity, functionality, and reusability/recyclability potential.

Synthesis, structure and magnetocaloric properties of a new two-dimensional gadolinium(III) coordination polymer based on azobenzene-2,2',3,3'-tetracarboxylic acid.

A new Gd3+ coordination polymer (CP), namely, poly[diaqua[μ4-1'-carboxy-3,3'-(diazene-1,2-diyl)dibenzene-1,2,2'-tricarboxylato]gadolinium(III)], [Gd(C16H7N2O8)(H2O)2]n, (I), has been synthesized hydrothermally from Gd(NO3)3·6H2O and azobenzene-2,2',3,3'-tetracarboxylic acid (H4abtc). The target solid has been characterized by single-crystal and powder X-ray diffraction, elemental analysis, IR spectroscopy and susceptibility measurements. CP (I) crystallizes in the monoclinic space group C2/c. The structure features a 4-connected topology in which Gd3+ ions are connected by carboxylate groups into a linear chain along the monoclinic symmetry direction. Adjacent one-dimensional aggregates are bridged by Habtc3- ligands to form a two-dimensional CP in the (10-1) plane. A very short hydrogen bond [O...O = 2.4393 (4) Å] links neighbouring layers into a three-dimensional network. A magnetic study revealed antiferromagnetic Gd...Gd coupling within the chain direction. CP (I) displays a significant magnetocaloric effect (MCE), with a maximum -ΔSm of 27.26 J kg-1 K-1 for ΔH = 7 T at 3.0 K. As the MCE in (I) exceeds that of the commercial magnetic refrigerant GGG (Gd3Ga5O12, -ΔSm = 24 J kg-1 K-1, ΔH = 30 kG), CP (I) can be regarded as a potential cryogenic material for low-temperature magnetic refrigeration.

Synthesis, Crystal Structure, and Luminescence of Cadmium(II) and Silver(I) Coordination Polymers Based on 1,3-Bis(1,2,4-triazol-1-yl)adamantane.

Coordination polymers with a new rigid ligand 1,3-bis(1,2,4-triazol-1-yl)adamantane (L) were prepared by its reaction with cadmium(II) or silver(I) nitrates. Crystal structure of the coordination polymers was determined using single-crystal X-ray diffraction analysis. Silver formed two-dimensional coordination polymer [Ag(L)NO3]n, in which metal ions are linked by 1,3-bis(1,2,4-triazol-1-yl)adamantane ligands, coordinated by nitrogen atoms at positions 2 and 4 of 1,2,4-triazole rings. Layers of the coordination polymer consist of rare 18- and 30-membered {Ag2L2} and {Ag4L4} metallocycles. Cadmium(II) nitrate formed two kinds of one-dimensional coordination polymers depending on the metal-to-ligand ratio used in the synthesis. Coordination polymer [Cd(L)2(NO3)2]n was obtained in case of a 1:2 M:L ratio, while for M:L = 2:1 product {[Cd(L)(NO3)2(CH3OH)]·0.5CH3OH}n was isolated. All coordination polymers demonstrated ligand-centered emission near 450 nm upon excitation at 370 nm.

Synthesis and crystal structure of a heterobimetallic cadmium-sodium complex of 1,3,5-triazine-2,4,6-trione, [CdNa2(C3H2N3O3)4(H2O)8

Heterobimetallic crystals of a cadmium-sodium complex of 1,3,5-triazine-2,4,6-trione, namely, μ-aqua-1:2κ2 O:O-hepta-aqua-1κ3 O,2κ2 O,3κ2 O-bis-(μ-4,6-dioxo-1,4,5,6-tetra-hydro-1,3,5-triazin-2-olato)-1:2κ2 O 2:N 1;2:3κ2 N 1:O 2-bis-(4,6-dioxo-1,4,5,6-tetra-hydro-1,3,5-triazin-2-olato)-1κO 2,3κO 2-2-cadmium-1,3-disodium, [CdNa2(C3H2N3O3)4(H2O)8], were grown by the single gel diffusion technique. The asymmetric unit of the title compound comprises four 1,3,5-triazine-2,4,6-trione ligands, two sodium atoms and one cadmium atom. Of the four ligands, two are monodentately coordinated to two Na atoms. The third ligand is coordinated bidentately to one Na and the Cd atom and the fourth is also coordinated bidentately to the Cd atom and the other Na atom. All the metal atoms are six-coordinate with a distorted octa-hedral geometry. The water mol-ecules bridge the Na atoms, constructing coordination polymer chains along the a axis and hence are linked by two Cd and one Na coordinations through the cyanuric acid ligands present in the coordination polymer chains, generating a two-dimensional coordination polymer in the (110) plane. The polymer formation is further assisted by means of many inter-molecular and intra-molecular N-H⋯O, O-H⋯O and O-H⋯N hydrogen bonds between the water mol-ecules and the ligands.

Two-dimensional coordination polymer-based nanosensor for sensitive and reliable nucleic acids detection in living cells

A reliable and sensitive strategy which can assess nucleic acid levels in living cells would be essential for fundamental research of biomedical applications. Some nanomaterial-based fluorescence biosensors recently developed for detecting nucleic acids, however, are often with expensive, complicated and time-consuming preparation process. Here, by using a facile bottom-up synthesis method, a two-dimensional (2D) coordination polymer (CP) nanosheet, [Cu(tz)] (Htz = 1,2,4-triazole), was successfully prepared after optimizing reaction conditions. These ultrathin CP nanosheets with thickness of 4.7 ± 1.1 nm could readily form nanosensors by assembly with DNA probes, which exhibited a low limit of detection (LOD) for p53 DNA fragment as 144 pmol/L. Furthermore, by integrating [Cu(tz)] nanosheets with hybridization chain reaction (HCR) probes, miR-21, one kind of microRNA upregulated in many cancer cells, can be sensitively detected with a LOD of 100 pmol/L and monitored in living cells, giving consistent results with those obtained by quantitative reverse-transcription polymerase chain reaction (qRT-PCR) analysis. Thus [Cu(tz)] nanosheets, which not only possess much better nucleic acids sensing performance than bulk cystals, but also exhibit nucleic acid delivery functions, could be used as a novel nanoplatform in biomedical imaging and sensing applications.