Sergey A. Sapchenko

Synthesis, crystal structures, luminescent and thermal properties of two new metal–organic coordination polymers based on zinc(II) carboxylates

Two new metal–organic coordination polymers, [NH2(CH3)2]2[Zn3(bdc)4]·DMF·H2O (1) (H2bdc = 1,4-benzenedicarboxylic acid) and [NH2(CH3)2]2[Zn3(bpdc)4]·5DMF (2) (H2bpdc = 4,4′-biphenyldicarboxylic acid), were synthesized by heating a DMF solution of Zn(NO3)2·6H2O, [NH2(CH3)2]Cl and organic carboxylic acids. Single-crystal X-ray structure analysis reveals that these compounds have 3D anionic framework structures built from zinc(II) carboxylate layers linked by carboxylate anions. Compounds 1 and 2 were characterized by IR, TGA and XRPD, and their luminescent properties were also investigated.

Confinement of Iodine Molecules into Triple-Helical Chains within Robust Metal–Organic Frameworks

During nuclear waste disposal process, radioactive iodine as a fission product can be released. The widespread implementation of sustainable nuclear energy thus requires the development of efficient iodine stores that have simultaneously high capacity, stability and more importantly, storage density (and hence minimized system volume). Here, we report high I2 adsorption in a series of robust porous metal–organic materials, MFM-300(M) (M = Al, Sc, Fe, In). MFM-300(Sc) exhibits fully reversible I2 uptake of 1.54 g g–1, and its structure remains completely unperturbed upon inclusion/removal of I2. Direct observation and quantification of the adsorption, binding domains and dynamics of guest I2 molecules within these hosts have been achieved using XPS, TGA-MS, high resolution synchrotron X-ray diffraction, pair distribution function analysis, Raman, terahertz and neutron spectroscopy, coupled with density functional theory modeling. These complementary techniques reveal a comprehensive understanding of the host–I2 and I2–I2 binding interactions at a molecular level. The initial binding site of I2 in MFM-300(Sc), I2I, is located near the bridging hydroxyl group of the [ScO4(OH)2] moiety [I2I···H–O = 2.263(9) Å] with an occupancy of 0.268. I2II is located interstitially between two phenyl rings of neighboring ligand molecules [I2II···phenyl ring = 3.378(9) and 4.228(5) Å]. I2II is 4.565(2) Å from the hydroxyl group with an occupancy of 0.208. Significantly, at high I2 loading an unprecedented self-aggregation of I2 molecules into triple-helical chains within the confined nanovoids has been observed at crystallographic resolution, leading to a highly efficient packing of I2 molecules with an exceptional I2 storage density of 3.08 g cm–3 in MFM-300(Sc).

Polyaniline-intercalated MIL-101: selective CO2 sorption and supercapacitor properties

A novel nanostructured hybrid material PANI@MIL-101(Cr) (PANI = polyaniline, MIL-101(Cr) – trichromium oxo-1,4-benzenedicarboxylate) was obtained by the intra-pore oxidative polymerization of guest aniline molecules within MIL-101. The compound was fully characterized using PXRD, TGA, FT-IR spectroscopy, XPS and SEM techniques. An introduction of PANI has dramatically increased the materials selectivity towards carbon dioxide over nitrogen with a CO2 uptake value of 2.26 mmol g−1 at 273 K (1.2 bar). Furthermore, cyclic voltammetry measurements revealed that PANI@MIL-101(Cr) is a supercapacitor with a relatively high specific capacitance value of 135 F g−1.

Hierarchical guest exchange and step-by-step activation of a biporous coordination framework.

A unique step-by-step activation of the biporous material via formation of the intermediate host-guest complex with a labile ligand has been presented on the example of the metal-organic framework [Zn4(ur)2(ndc)4]. The difference in the chemical environment of channels allows highly selective separation of the mixture of S4N4 and benzene.

Coordination polymers with adjustable dimensionality based on CuII and bis-imidazolyl bridging ligand

Abstract1,4-Bis(imidazol-1-yl)butane was synthesized from imidazole and 1,4-dibromobutane in an alkaline medium. A variation of the molar ratio of reagents in the system copper(II) chloride dihydrate and 1,4-bis(imidazol-1-yl)butane (bImB) upon heating in N,N-dimethylformamide resulted in the synthesis of two new coordination polymers [Cu(bImB)Cl2] (1) and [Cu(bImB)2Cl2] (2), which were structurally characterized. Product 1 was found to possess a chain structure, while structure 2 is built of neutral layers, with the dimensionality of the extended coordination structures being determined by the reaction conditions. The new compounds were characterized by IR spectroscopy, elemental analysis, and powder X-ray diffraction data.

Synthesis, structure, and properties of a new layered coordination polymer based on zinc(II) carboxylate

Heating of zinc(II) nitrate and 2,5-thiophenedicarboxylic acid (H2Tdc) in the presence of hexamethylenetetramine in N-methylpyrrolidone (Nmp) gave the crystals of a layered coordination polymer [Zn2(Nmp)2(Tdc)2] · 2Nmp · 0.5H2O, which were studied by X-ray diffraction. The compound was characterized by IR spectroscopy, elemental and thermogravimetric analyses, and luminescence measurements.

Cage amines in the metal–organic frameworks chemistry

Abstract Nitrogen-rich porous materials have outstanding gas sorption and separation capacity. Using cage amines in the synthesis of metal–organic frameworks is a simple approach for generating the free nitrogen donor centers within the channels of porous materials without the post-synthetic modification. 1,4-Diazabicyclo[2.2.2]octane has a linear arrangement of nitrogen centers and can be used as a linear linker for the design of porous MOF materials. Urotropine has four nitrogen atoms and can act as a tetrahedral four-connected, pyramidal three-connected or bent two-connected linker. Such a diversity of coordination possibilities enriches the structural chemistry of MOFs and allows obtaining the frameworks with unique secondary building units and topology. The presence of cage amines in the structure affects the sorption characteristics of the materials. They demonstrate high selectivity to CO2 and can participate as a heterogeneous base catalyst in the organic reactions. Besides that the cage-amine based metal–organic frameworks demonstrate photoluminescent properties and can be used as nanoreactors for photochemical transformations. These compounds are also an important object of thermodynamic studies helping us better understand the nature of host–guest interaction in the supramolecular systems.

A Cryptand Metal–Organic Framework as a Platform for the Selective Uptake and Detection of Group I Metal Cations

The metal-organic framework (MOF) complex (H3 O)2 [Zn4 (ur)(Hfdc)2 (fdc)4 ] (1, ur=urotropine, H2 fdc=furan-2,5-dicarboxylic acid) incorporates cryptand-like cavities, which can be used to separate and detect Rb+ and Cs+ optically. This is the first example of the effective employment of a MOF material for optical detection of these cations.

Microporous coordination polymer [Zn4(dmf)(ur)2(ndc)4] as a heterogeneous catalyst for the Knoevenagel reaction

The catalytic properties of the microporous metal-organic coordination polymer [Zn4(dmf)(ur)2(ndc)4] (dmf is N,N’-dimethylformamide, ur is urotropine, and ndc2- is 2,6-naphthalenedicarboxylate) for the Knoevenagel reaction were studied. The reaction between aromatic aldehydes (benzaldehyde, α-naphthaldehyde, 4-biphenylaldehyde, and 1-pyrenaldehyde) and malononitrile was studied. The coordination polymer was shown to be a heterogeneous catalyst that makes it possible to achieve 95% yield in the reaction between benzaldehyde and malononitrile. The selectivity of the catalyst depends on the size of aldehydes used in the reaction.

Benzene sorption by a microporous coordination polymer based on a zinc carboxylate

Benzene vapor sorption by the organometallic coordination polymer [Zn2(bdc)2(dabco)] (H2bdc = benzene-1,4-dicarboxylic acid, dabco = diazabicyclo[2.2.2]octane) is reported. The [Zn2(bdc)2(dabco)] polymer has a high C6H6 sorption capacity of up to 3.8 mol of benzene per formula unit. The heat of sorption has been determined, and its dependence on the composition of the inclusion compound has been investigated. Included benzene molecules are nonequivalent in terms of the energy of their interaction with the metal-organic framework.