Metal-organic Coordination Polymers Research Articles

Depositing Molecular Graphene Nanoribbons on Ag(111) by Electrospray Controlled Ion Beam Deposition: Self-Assembly and On-Surface Transformations.

The chemical processing of low‐dimensional carbon nanostructures is crucial for their integration in future devices. Here we apply a new methodology in atomically precise engineering by combining multistep solution synthesis of N‐doped molecular graphene nanoribbons (GNRs) with mass‐selected ultra‐high vacuum electrospray controlled ion beam deposition on surfaces and real‐space visualisation by scanning tunnelling microscopy. We demonstrate how this method yields solely a controllable amount of single, otherwise unsublimable, GNRs of 2.9 nm length on a planar Ag(111) surface. This methodology allows for further processing by employing on‐surface synthesis protocols and exploiting the reactivity of the substrate. Following multiple chemical transformations, the GNRs provide reactive building blocks to form extended, metal–organic coordination polymers.

Depositing Molecular Graphene Nanoribbons on Ag(111) by Electrospray Controlled Ion Beam Deposition: Self‐Assembly and On‐Surface Transformations

AbstractThe chemical processing of low‐dimensional carbon nanostructures is crucial for their integration in future devices. Here we apply a new methodology in atomically precise engineering by combining multistep solution synthesis of N‐doped molecular graphene nanoribbons (GNRs) with mass‐selected ultra‐high vacuum electrospray controlled ion beam deposition on surfaces and real‐space visualisation by scanning tunnelling microscopy. We demonstrate how this method yields solely a controllable amount of single, otherwise unsublimable, GNRs of 2.9 nm length on a planar Ag(111) surface. This methodology allows for further processing by employing on‐surface synthesis protocols and exploiting the reactivity of the substrate. Following multiple chemical transformations, the GNRs provide reactive building blocks to form extended, metal–organic coordination polymers.

A Zn(II) coordination polymer with 5-ethoxy-isophthalate linker: synthesis, crystal structure, and fluorescent properties

A new Zn(II) metal–organic coordination polymer, {[Zn(eoip)(bipy)]} n (1), (H2eoip = 5-ethoxy-isophthalic acid, bipy = 4,4'-bipyridine), was assembled under hydrothermal condition by the reactions of Zn(II) acetate with H2eoip and bipy. Complex 1 was characterized by elemental analysis, IR spectroscopy and X-ray single-crystal diffraction. The results reveal that complex 1 is a two-dimensional layered structure. In addition, fluorescent properties of 1 were also investigated.

Directed molecular structure design of coordination polymers with different ligands for regulating output performance of triboelectric nanogenerators.

A triboelectric nanogenerator (TENG) provides an effective method to harvest mechanical energy from the environment. The morphology and structure of frictional electrode materials of this type of device affect the output performance significantly. Metal-organic coordination polymers (CPs) with special structure advantages offer a vast pool of materials enabling high performances. Two Co-CPs based on terephthalic acid and 2,5-dihydroxyterephthalic acid ligands, respectively, were used to fabricate TENGs. Detailed electrical characterizations of the TENG devices revealed that the introduction of the substituent groups in the organic ligands leads to the structural changes of CPs, which ultimately leads to significant differences in the output performance.

Hydroxamate based transition metal–organic coordination polymers with semiconductive properties

New coordination polymers based on a bis-hydroxamate linker, ONDI2−, exhibit semiconductive properties benefiting from their π–π stacking structure.

Synthesis of Metal–Organic Coordination Polymers and Their Derived Nanostructures for Organic Dye Removal and Analyte Detection

Synthesis of Metal–Organic Coordination Polymers and Their Derived Nanostructures for Organic Dye Removal and Analyte Detection

A luminescence europium Metal-organic coordination polymer for Room-Temperature X-ray detection

In this paper, a novel Eu ions-based metal–organic coordination polymer (MOCP) named Eu(1,3,6,8-PTS)(H2O)7·4H2OHbipy (1) (PTS = pyrenetetrasulfonic acid) has been prepared, and its structure, stability, photoluminescence and scintillation properties were systematically investigated. Compound 1 gives a peculiar “snake-shaped” chain structure with the aid of π-π stacking effect of 4,4′-bipyridine auxiliary template. An efficient and stable light emission was detected under X-ray irradiation, which presents an excellent linear response to X-ray dose. Moreover, this compound demonstrates high radiation stability, illustrating its potential as a scintillator for X-ray detection. This work not only provides guidance for the design and fabrication of sulfonic ligand derived MOCPs with Eu (III) ions coordiantion, but also demonstrates the potential of MOCPs scintillators for X-ray detection technology.

Efficient ratiometric fluorescence probe based on dual-emission luminescent lanthanide coordination polymer for amyloid β-peptide detection

As an important biomarker for early Alzheimer’s disease (AD) diagnostics and a valuable therapeutic target, amyloid β peptide (Aβ) in blood has attracted extensive attention concerning its detection and monitoring. The tough challenges for monitoring subtle changes of Aβ in blood are low expression and high interference from environmental factors. Here, we constructed a ratiometric sensor based on dual-emission luminescent lanthanide metal–organic coordination polymer (DE-LMOCP) as fluorescence probe for simple, sensitive and accurate detection of Aβ. The DE-LMOCP (luminol-Tb-GMP-Cu) fluorescent probe was composed of terbium ion(Tb3+) as the center metal ions, cupric ion(Cu2+) as a cofactor for Tb3+ fluorescence silence, guanine monophosphate (GMP) as a bridging ligand can strengthen the fluorescence of Tb3+, and luminol as an auxiliary ligand. In the DE-LMOCP fluorescent probe, the fluorescence of the GMP-Tb is quite weak because the existing cofactor Cu2+ prevents the energy transfer of intramolecular between GMP and Tb3+ and results in the quench of GMP-Tb fluorescence. The fluorescence of luminol acts as inner reference. In the presence of Aβ, the high binding affinity of Aβ for Cu2+ causes a remarkable emission enhancement of GMP-Tb and suppresses the quenching effect. However, the fluorescence emission of luminol remains constant as inner reference. Hence, sensitive and accurate determination of Aβ were performed by the ratio of the fluorescence of luminol (F430) to the Tb3+(F547). With this ratiometric probe, Aβ was determined with sensitivity down to 20 pM. Moreover, the ratiometric probe was successfully used to the detection of Aβ in human plasma with satisfactory results due to its capability to eliminate auto-fluorescence. Significantly, it exhibited sound specificity and selectivity to recognize Aβ1−40, and successfully applied to visual detection of Aβ, which validates the potential on-site application. Given the analytical characteristics with high sensitivity, specificity, and accuracy, the ratiometric fluorescence sensor may have great potential in applications of Aβ1−40 detection and the early diagnosis of Alzheimer’s disease, as well as point-of-care tests.

A novel rare-earth luminescent coordination polymer showing potential semiconductor characteristic constructed by anthracene-based dicarboxylic acid ligand (H2L)

• A new member of rare-earth coordination polymer based on H 2 L was successfully synthesized using a solvothermal method. • The crystal structure, morphology feature and thermostability of the obtained La-CP were systematically characterized and analyzed by a series of measurement techniques. • La-CP exhibited a yellow fluorescence emission band with a QY of 1.81%. • Its semiconductor characteristic was confirmed by the optical band gaps from DRS data as well as the electronic structure calculation. In this study, one new rare-earth lanthanum(Ⅲ) metal-organic coordination polymer {[La(L) 1.5 (H 2 O)(DMF)]∙DMF} n (H 2 L = 4,4’-(diethynylanthracene-9,10-diyl) dibenzoic acid) labeled as La-CP was successfully constructed via a solvothermal process. Structure analysis of the obtained La-CP revealed that it crystallized in the triclinic space group P -1, in which each La 3+ ion was coordinated to eight oxygen atoms to form a distorted square antiprism geometry. It was important to observe π-π stacking between adjacent ligand moieties of La-CP with face-to-face distances of 3.385 and 3.447 Å, endowing charge carriers with the possibility of through-space transport. The optical band gap of 2.23 eV evaluated from the UV-vis diffuse reflectance spectrum, coupled with electronic band structure calculation, provided reliable evidence of its potential semiconductor characteristic. In addition, La-CP exhibited a yellow fluorescence emission and a comparable quantum yield of 1.81% to that of free ligand H 2 L in terms of its optical properties. This work not only expands the list of rare-earth lanthanide coordination polymers but also offers useful guidance for materials design and related properties modulation of coordination polymers to some extent.

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.

Fabrication of a Novel Phenolic Compound Biosensor Using Laccase Enzyme and Metal-organic Coordination Polymers

Hydroquinone (HQ) sensitive electrochemical biosensing was performed using new nanocomposites of carboxylated graphene (GrCOOH) embedded in metal-organic coordination polymers (MOCPs) as efficient matrices for laccase (Lac) immobilization. GrCOOH nanosheets were used to pre-adsorb of HAuCl4 and act as anchor sites; they help to form MOCPs and more coordinate between gold ions and 4-aminothiophenol (4-ATP) ligand. According to the Tafel plot the mechanism was diffusion for HQ redox reactions on the proposed modified electrode surface and an electron process was in the rate-determining stage. It was concluded that this redox reaction was involved the same number of protons and electrons. The construction of GrCOOH-MOCPs one-pot entrapped Lac exhibited enhanced redox currents over MOCPs for HQ electrochemical oxidation and reduction and enhanced sensitivity and low detection limit (1.70 µM), being superior to other Lac biosensors. Furthermore, this biosensor was tested in real samples and demonstrated acceptable recoveries in real water samples and had good stability for one week.

Cobalt metal-organic coordination polymer constructed from 2,3′-oxybisbenzoic acid and 1,3-di(pyridin-4-yl)propane: Crystal structure, slow magnetic relaxation and catalytic properties

A new metal-organic coordination polymer, [Co(2,3′-oba)(dpp)]n (1) constructed from 2,3′-oxybisbenzoic acid (2,3′-H2oba) and 1,3-di(pyridin-4-yl)propane (dpp) was synthesized by hydrothermal method. The complex 1 is a 2D network structure connected by Co-2,3′-oba-Co-dpp helical chains. The temperature-dependent magnetic susceptibility and alternating current (ac) magnetic susceptibility measurements of the complex 1 were discussed. The complex 1 was shown to be a single-molecule magnet with slow magnetic relaxation behavior having an energy barrier Ueff of 15 ​K and τ0 =1.56 ​× ​10−6 ​s. As a catalyst, complex 1 exhibited excellent catalytic properties on the activation of peroxymonsulfate (PMS) for the dyes degradation. Specifically, an almost complete degradation of Rhb in aqueous solution was achieved by complex 1/PMS system with an efficiency of 99% within 15 ​min. The feasible active components were explored by quenching experiments, and the results showed that sulfate radicals generated in the degradation system was the main active constituent in the degradation process. The complex 1 has a highly stable skeleton structure which enabled its recycling in the dye degradation system. The obtained results provide an effective method for high degradation efficiencies of dyes in water.

Synthesis of coordination polymers based on a 2,2′-dimethoxy-1,1′-biphenyl scaffold and Hg(II), Co(II), or Zn(II)

In this study, 3,3′-di(pyridin-4-yl)-(2,2′-dimethoxy-[1,1′-biphenyl]) (L) was synthetized, structurally characterized by X-ray crystallography and combined with HgCl2, CoCl2, or ZnSiF6 for the formation of three coordination polymers ((HgCl2)2(L), (CoCl2)2(L)2.CHCl3, and Zn(SiF6)(L)2). The crystal structures of synthesis compound indicate the formation of different types of coordination modes, and each adopts a mono (1D) or tri-dimensional (3D) framework by C–H···π interactions. In (CoCl2)2(L)2, the combination of Co(II) with L forms a metallo-macrocycle, while in the other compounds two helical infinite networks were characterized. Compounds (HgCl2)2(L) made of two helical chains with opposite chirality (P and M), and Zn(SiF6)(L)2 exhibits helical tubular assemblies of the L attached to two Zn(SiF6)∞ pillars. This work may pave the way to further study the chemical, structural and physicochemical properties of metal-organic coordination polymers.

Comprehensive and High-throughput Electrolysis of Water and Urea by 3-5 nm Nickel and Copper Coordination Polymers.

Metal-organic coordination polymers (CP) have attracted the scientific attention for electrochemical water oxidation as it has the similar coordination structure like natural photosynthetic coordinated complex. However, the harsh synthesis conditions and bulky nature pose a major challenge in the field of catalysis. Herein, 3-5 nm CP particles synthesized at room temperature using aqueous solutions of Ni2+ /Cu2+ and 2,5-dihydroxyterepthalic acid as precursor were applied for alkaline water and urea electrolysis. The overpotential required is only 300 mV at 10 mA cm-2 by Nano-Ni CP for water oxidation, with turnover frequency (TOF) of 21.4 s-1 which is around 8 times higher than its bulk-counterpart. Overall water and urea splitting were achieved with Nano-Cu (-) ∥ Nano-Ni (+) couple on Ni foam at 1.69 and 1.52 V to achieve 10 mA cm-2 , respectively. High electrochemical surface area (ECSA), high TOF, and enhanced mass diffusion are found to be the key parameters responsible for the state-of-the-art water and urea splitting performances of nano-CPs as compared to their bulk counterparts.

Synthesis and Crystal Structure of Cadmium(II) Metal-Organic Coordination Polymers with Octafluorobiphenyl-4,4'-Dicarboxylate

Synthesis and Crystal Structure of Cadmium(II) Metal-Organic Coordination Polymers with Octafluorobiphenyl-4,4'-Dicarboxylate

Redox-Active Tin Metal-Organic Framework with a Thiolate-Based Ligand.

Metal-organic frameworks (MOFs) and coordination polymers composed of thiolates as coordinating functional groups are interesting materials with unique optical and electronical properties. Herein, we report the preparation of KGF-4 and KGF-10, two Sn-MOF crystal structures with bonds between Sn and thiolate. KGF-10 was isolated as a pure phase and found to exhibit redox properties and a semiconducting band structure, as confirmed by first-principles (density functional theory) calculations.

Combustion characteristics of EMOFs/oxygenated salts novel thermite for green energetic applications

Metal-based thermites, especially those based on aluminum, have been recently included in materials for energetic applications such as pyrotechnics, propellants, and explosives. In parallel, several advances in the field of Metal-Organic Frameworks (MOFs) and Coordination Polymers (CPs) have as well paved the road for their use in developing novel energetic materials. In this context, we are introducing new thermites compositions with low ignition temperature, stable propulsive force, and high reactivity. These thermites are based on the [Cu4Na(Mtta)5(CH3CN)]n (Mtta = 5-Methyl-1H-tetrazole) energetic metal-organic framework (EMOF-1) as a fuel instead of pure metals. We first report the synthesis of an energetic MOF via the microwave-assisted technique as a more rapid and greener method. The efficiency of composites based on EMOF-1 and Al together with various oxygenated salts were investigated. Multiple instruments are involved to characterize the morphology and the structure of EMOF-1 and the developed systems, such as SEM-EDX, FTIR, and XRD. The combustion behavior of the novel composites was evaluated by TGA/DSC, bomb calorimetry and laser ignition. Additionally, the apparent kinetic parameters (activation energy & frequency factor) were calculated by the Kissinger and Ozawa approaches. The results revealed that the new thermite mixtures exhibit superior combustion characteristics of one and half to two-folds the average heat of combustion compared to aluminum-based ones, at almost half the ignition temperature. In this sense, the combustion reaction proceeds faster, easier (reduced activation energy), the ignition temperatures are noticeably lowered, and the heat released has considerably improved. In addition, they exhibited stable force with longer burning time. Among them, EMOF-1/KIO4 thermite exhibits the highest heat release (4.7 kJ/g), while EMOF-1/NH4NO3 thermite shows the lowest onset reaction temperature (224 ᵒC). EMOF-1/KClO4 yields the highest average force (8.4 N), calculated pressure (1365 kPa), pressurization rate (0.32 kPa/μs) and the longest burning time assigned to EMOF-1/K2S2O8 (40 ms).

Structure and photocatalytic performance comparison of two distinctive copper phenylacetylides

AbstractA new copper phenylacetylide of PhC2Cu2.5 was prepared and compared with PhC2Cu, a copper‐based metal–organic coordination polymer we reported previously. Based on the characterizations on the structures of the two prepared samples, they possessed significantly different crystal structures and similar micro and band structures. Interestingly, they also showed different preferences for the photocatalytic degradation of methyl orange (MO) and 2,4‐diclorophenol (2,4‐DCP). The active species trap experimental results show that different active species were required for the degradation of MO and 2,4‐DCP, resulting to different degradation pathways and mechanism. At last, different preferentially production of active species by PhC2Cu2.5 and PhC2Cu were studied by electrochemical measurements and fluorescence spectra, as well as the photocatalytic productions of reactive oxygen species by PhC2Cu and PhC2Cu2.5, which further demonstrated the obtained conclusions by active species trap experimental results. This work developed a new copper phenylacetylide of PhC2Cu2.5 as a photocatalyst and demonstrated the different degradation pathways of MO and 2,4‐DCP.

Understanding the Self-Templating of Hierarchically Porous Carbon Electrocatalysts Using Group 2 Coordination Polymers

Self-templating of hierarchical porosity in carbon materials can be realized by the pyrolysis of well-designed metal-organic precursors. While this strategy is elegant and scalable, detailed mechanistic understanding of the self-templating process is lacking. We now present a systematic investigation of the microstructural evolution in porous carbons, including hierarchically micro-/meso-/macroporous materials with variable mesopore size. We focus on a homologous series of well-defined metal-organic coordination polymers, combining the highly abundant Group 2 ions (Mg2+, Ca2+, Sr2+, Ba2+) with a common ligand. To understand the role of the metal ion in directing the morphology of the ultimate N-doped carbons, we performed a detailed investigation using electron microscopy (HRSEM, HRTEM, EDS), N2 porosimetry, XRD, XPS and Raman spectroscopy. The rich morphological variations in the carbons determine their activity as metal-free electrocatalysts towards the oxygen reduction reaction. In particular, the reaction selectivity (2e – vs. 4e – pathways) is directed by competition between kinetics and mass transfer, due to confinement in mesopores. Figure 1

Synthesis and the crystal structure of a new chiral metal-organic coordination polymer based on l-proline-substituted 2-aminobenzene-1,4-dicarboxylic acid derivative

Synthesis and the crystal structure of a new chiral metal-organic coordination polymer based on l-proline-substituted 2-aminobenzene-1,4-dicarboxylic acid derivative