Expansion of the operational temperature range for polymer-electrolyte membrane fuel cells (PEMFCs) above 200 °C significantly reduces hydrogen purification requirements. Here, we report a hybrid composite of poly(2,5-benzimidazole) (ABPBI) and CsH2PO4, doped with H3PO4, as a PEM for PEMFC operation at >200 °C up to 250 °C and beyond. The optimal ratio of ABPBI repeating units to CsH2PO4 is 1:1 (mol/mol). Materials are extensively characterized by elemental analysis, scanning electron microscopy, HAADF STEM, elemental mapping, electrochemical impedance spectroscopy, proton conductivity, mechanical testing, and Fourier transform infrared spectroscopy. It is suggested that PEMFCs with the extended operational temperature range (>220 °C) might be categorized as ultrahigh-temperature polymer-electrolyte membrane fuel cells (UT-PEMFCs).

Three new Ni(II) coordination compounds with anions of 4,8-disulfo-2,6-naphthalenedicarboxylic acid (H4dsndc) and 1,2-bis(4-pyridyl)ethylene (bpe), differing in dimensionality and structure, were obtained: the molecular complex [Ni(H2O)52(bpe)](dsndc), the one-dimensional coordination polymer [Ni(H2O)4(bpe)](H2dsndc)·2H2O, and the two-dimensional coordination polymer [Ni(H2O)32(bpe)2(dsndc)]·2H2O. The structures of the compounds were determined by single-crystal X-ray diffraction analysis. The compound [Ni(H2O)4(bpe)](H2dsndc)·2H2O was obtained in chemically and phase-pure form and characterized by a standard set of physicochemical methods (powder X-ray diffraction, elemental and thermogravimetric analyses, and IR spectroscopy).

Two new anionic scandium(III)-organic frameworks based on 2,5-thiophendicarboxylate ligands have been synthesized, and their structure has been determined by the single-crystal X-ray diffraction analysis. Compound (H2NMe2)[Sc3(H2O)2(OH)2(tdc)4]·C4H8O2·H2O (1) (tdc2− = 2,5-thiophendicarboxylate, H2NMe2+ = dimethylammonium cation, C4H8O2 = 1,4-dioxane) represents a two-dimensional metal-organic framework with the AAA type arrangement of layers. Compound (Hdabco)[Sc3(OH)2(tdc)4]·DMF (2) (dabco = 1,4-diazabicyclo[2.2.2]octane, DMF = N, N-dimethylformamide) is a three-dimensional metal-organic framework with the channels of (4⋅5) Å2 occupied by guest DMF molecules and protonated dabco molecules acting as counterions. After optimizing the synthesis conditions, compound 2 has been obtained in a chemically and phase pure form and characterized by a complex of physicochemical methods of investigations such as powder X-ray diffraction, chemical and thermogravimetric analyses and IR spectroscopy. The stability of 2 in aqueous solutions, humid and dry atmosphere during at least a month has been confirmed by powder X-ray diffraction analysis. The exchange of Hdabco+ cations to various metal cations in aqueous solutions has been studied using 2 as an anionic adsorbent, revealing a pronounced affinity of this MOF towards Fe(III) ions with more than 50

C3H6 adsorption on a family of NIIC-20-G (G = glycol) MOFs is carried out. The C3H6 adsorption capacities at 1 bar vary from 109.3 to 168 ml & sdot;g-1 (273 K) and from 74.2 to 113.3 ml & sdot;g-1 (298 K), depending on the nature of G. The following highest IAST adsorption selectivity values (S) are obtained at 298 K, 1:1 gas mixture, 1 bar: S (C3H6/CO2) = 7.4, S(C3H6/CH4) = 587.0, S(C3H6/C2H6) = 4.4, S(C3H6/C2H4) = 7.0, S(C3H8/C3H6) = 2.1. The isosteric heats of the C3H6 adsorption range from 32.4 to 38.0 kJ center dot mol-1, which are lower than that of C3H8, suggesting enthalpy-driven preferential adsorption of propane over propylene. Theoretical DFT and GCMC calculations support the experimental results and provide more detailed information on the nature of adsorption centers of propane and propylene molecules. Multiple breakthrough separation experiments are carried out for NIIC-20-Pr (Pr = propyleneglycol) using different C3H6/C2H4 and C3H8/C3H6 gas mixtures. The productivity of ethylene ranges from 2.60 to 2.94 mol center dot kg-1, the propylene productivity is 0.56 mol kg-1. Given the remarkable fundamental adsorption characteristics, the NIIC-20-G porous materials should be considered among the best solutions for efficient and economically viable separation of industrially important gas mixtures.

Three new anionic three-dimensional metal-organic frameworks based on heterocyclic polycarboxylate ligands have been synthesized: (H2NMe2)3[Zn2{NaZn2}(dabco)2(tdc)6]center dot 4.5DMF center dot H2O (1, CCDC 2527083), (H2NMe2) [NaZn(fdc)2] (2, CCDC 2527084), (H2NMe2)[CdLi(btdc)2] (3, CCDC 2527085), where tdc2-= 2,5-thiophenedi-carboxylate, dabco = 1,4-diazabicyclo[2.2.2]octane, DMF = N,N-dimethylformamide, fdc2-= 2,5-furanedicar-boxylate, btdc2-= 2,2 '-bithiophene-5,5 '-dicarboxylate. The structure of the compounds has been established by single crystal X-ray diffraction analysis; the chemical and phase purity of compounds 2 and 3 has been proved by elemental, thermogravimetric and powder X-ray diffraction analyses and IR spectroscopy. The luminescence excitation and emission spectra of the solid phases 2 and 3 have been recorded, and the quantum yields have been obtained. The influence of mono-, di-and trivalent metal cations on the luminescence intensity of the suspensions of the MOF 3 has been investigated, and the luminescence response of the MOF suspensions to the presence of Co(II) and Ni(II) has been revealed and studied quantitatively.

Ion exchange membranes with high monovalent ion selectivity are essential for extracting valuable components from natural and waste waters. One of the approaches to their fabrication is the creation of nanostructured materials with ion-conducting channels. In this study, materials based on cardo polybenzimidazole (PBI-O-PhT) containing Zn2+, Cr3+ and Cu2+ ions were obtained and used for the first time for electrodialysis separation. The formation of crosslinked structure due to metal-benzimidazole coordination bonds was demonstrated. The obtained metal-polymer membranes have ionic conductivity comparable to commercial ones, reaching 0.32 mS cm-1, and high values of nitrate ion transport numbers (99.2 %). It is shown that the obtained membranes achieve incredibly high values of selectivity coefficients for anion separation. The highest and most stable values were obtained for the copper-containing membrane PBI/Cu-50, which are P(NO3/SO4) = 729, P(Cl/SO4) = 109 and P(NO3/Cl) = 6.66.

Four new porous homochiral metal–organic frameworks (MOFs), [M2(camph)2(bpa)]∙Solv (M = Co(II), Ni(II), Cu(II) and Zn(II)), based on (+)-camphoric acid (H2camph) and 1,2-bis(4-pyridyl)ethane (bpa) were synthesized and characterized. The crystal structures of [Ni2(camph)2(bpa)] and [Zn2(camph)2(bpa)] were established by single-crystal X-ray diffraction analysis. Powder X-ray data prove the phase purity and isostructural nature of all four compounds. The thermal stability of [M2(camph)2(bpa)] was found to depend on the electronic configuration, as well as on the redox properties of the metal cation, and varied from 225 °C (M = Zn2+) to 375 °C (M = Ni2+). The reversible, solvent-induced sponge-like dynamics of the coordination frameworks was thoroughly investigated. Changes in the positions of reflexes, related to the length of the flexible bpa linker, were observed by powder XRD, pointing to transitions between an open-framework phase and a squeezed, non-porous phase in a crystal-to-crystal manner, while the integrity and connectivity of the coordination network were maintained. Size-selective adsorption from a benzene–cyclohexane 1:1 mixture on [Zn2(camph)2(bpa)] was studied by 1H NMR analysis. The benzene-favorable composition of guest molecules (C6H6:C6H12 = 5:1) occluded within the host crystalline sponge revealed a preferable adsorption affinity towards smaller benzene compared with larger cyclohexane. High framework stability in various solvents, as well as successful molecular separation in the liquid state, validates the potential utilization of chiral porous metal(II) camphorate MOFs in important stereoselective applications.

Three new three-dimensional (3D) metal-organic frameworks [M2(ttdc)2(dabco)] (M = Zn(II), 1-Zn; Cu(II), 1-Cu; and Zn/Cu, 1-ZnCu) based on thieno[3,2-b]thiophene-2,5-dicarboxylate (ttdc2-) were synthesized and characterized by a combination of physicochemical methods (single crystal X-ray diffraction, powder X-ray diffraction, chemical and thermogravimetric analyses and IR spectroscopy). 1-Cu demonstrated permanent porosity (Vpore = 0.790 cm3 g-1 and SBET = 1725 m2 g-1) and significant CO2, CH4, C2H2, C2H4 and C2H6 gas uptakes under ambient conditions. The adsorption selectivities for gas mixtures, calculated by IAST, were 10.8 (10.7), 14.6 (9.4), 1.7 (1.6) and 1.5 (1.6) for the equimolar gas mixture compositions CO2/N2, C2H6/CH4, C2H6/C2H4 and C2H6/C2H2 at 1 bar and 273 K (298 K), respectively. The mixed-metal compound 1-ZnCu was prepared by a crystal-to-crystal ion exchange metathesis reaction from 1-Zn with a 52% degree of ion substitution, confirmed by energy-dispersive X-ray spectroscopy, optical microscopy and single crystal X-ray diffraction analysis.

New porous metal-organic frameworks (MOF) [Cd7(Btdc)7(Bpa)2(Dmf)2(H2O)2]·15Dmf·2H2O (I) and [Cd7(Btdc)7(Bpe)2(Dmf)2]·15Dmf·3H2O (II) (H2Btdc is 2,2′-bithiophene-5,5′-dicarboxylic acid, Bpa is 1,2-bis(4-pyridyl)ethane, Bpe is 1,2-bis(4-pyridyl)ethylene, and Dmf is N,N-dimethylformamide) are synthesized under solvatothermal conditions. The structures and compositions of the compounds are determined by single-crystal X-ray diffraction (XRD) (CIF files ССDС nos. 2364290 (I) and 2364289 (II)) and confirmed by powder XRD, elemental analysis, thermogravimetry, and IR spectroscopy. Compound I has a 2D structure based on the heptanuclear discrete building unit Cd7 with the linear structure. Compound II is a 3D MOF in which the Cd7 building units are linked into a continuous chain motif due to additional interactions. The formation of either discrete or continuous chains is directly related to the nature of the N-donor bridging ligand (Bpe or Bpa). Compounds I and II have open structures with the accessible volume about 50

Получено пять новых металл-органических координационных полимеров на основе 4,8-дисульфо-2,6-нафталиндикарбоновой кислоты (H4dsndc) [Cd2(dsndc)(dmf)6] (1), [Mn2(dsndc)(dmf)6] (2), [Zn2(dsndc)(dmf)6] (3), [Co2(dsndc)(dmf)6] (4) и [Cd2(dsndc)(dma)6] (5) (dmf = N,N-диметилформамид, dma = N,N-диметилацетамид), четыре из которых (1–4) являются изоструктурными слоистыми координационными полимерами. Структуры всех соединений установлены методом монокристального рентгеноструктурного анализа. Соединения 1-3 и 5 получены в химически- и фазовочистом виде и охарактеризованы стандартным комплексом физико-химических методов (РФА, ИК, ТГА и CHN). Для соединения 3 записаны спектры возбуждения и испускания фотолюминесценции и получен квантовый выход, который составил 18 %.

Polybenzimidazoles (PBI) doped with phosphoric acid are a promising electrolyte for medium-temperature fuel cells. However, to be effective at high temperatures in the presence of acid, the mechanical and conductive properties of the material must be stable and no critical increase in gas permeability is required. This work proposes an approach to improve the properties of PBI-O-PhT-based materials by combining two previously known methods: covalent crosslinking with silane (3-bromopropyl)trimethoxysilane (Si-Br) and doping with silicon oxide (SiO2), including grafted imidazolinpropyl groups (SiO(2)Im). The silanol cross-linked samples exhibited higher stability when tested with Fenton's reagent and retained their morphological integrity even after 360 h of testing. The study shows that covalent crosslinking improves the stability of dopant particles in the membrane matrix and prevents their leaching during acid treatment. Additionally, the incorporation of silicon oxides enhances the proton conductivity of samples with covalent cross-linking and reduces gas permeability compared to the original PBI membrane. Proton conductivity of the covalent cross-linked samples reaches 50 and 55 mS center dot cm(-1) at oxide contents of 5 wt% SiO(2)Im and 10 wt% SiO2, respectively.

Five new metal-organic frameworks based on 4,8-disulfo-2,6-naphthalenedicarboxylic acid (H4dsndc) are obtained: [Cd2(dsndc)(dmf)6] (1), [Mn2(dsndc)(dmf)6] (2), [Zn2(dsndc)(dmf)6] (3), [Co2(dsndc)(dmf)6] (4), and [Cd2(dsndc)(dma)6] (5) (DMF = N,N-dimethylformamide, DMA = N,N-dimethylacetamide). The four of them (1–4) are isostructural layered coordination polymers. The structures of all compounds are determined by the single crystal X-ray diffraction analysis. Compounds 1–3 and 5 are obtained as chemically and phase-pure and are characterized by the standard complex of physicochemical techniques (powder XRD, IR, TGA, and CHN). Photoluminescence excitation and emission spectra are recorded for compound 3, and a quantum yield of 18

The progress of modern technologies and the requirements imposed on the production ecology demand the development of new ion-exchange membrane polymer materials with a set of desired properties. These materials are used in liquid and gas separation and purification systems, chemical and electrochemical syntheses, and alternative energetics. Membrane materials based on perfluorosulfonic acid polymers (PFSA) possess a set of characteristics necessary for their practical application: high ionic conductivity and selectivity and good chemical stability, strength, and elasticity. This review addresses the microstructure of PFSA membranes and its change induced by water and solvent uptake and discusses the features of ion and gas transport, mechanical properties, and the dependence of a number of parameters on polymer chain length and ionic form.

Five new metal–organic frameworks based on Mn(II) and 2,2′-bithiophen-5,5′-dicarboxylate (btdc2–) with various chelating N-donor ligands (2,2′-bipyridyl = bpy; 5,5′-dimethyl-2,2′-bipyridyl = 5,5′-dmbpy; 4,4′-dimethyl-2,2′-bipyridyl = 4,4′-dmbpy) [Mn3(btdc)3(bpy)2]·4DMF, 1; [Mn3(btdc)3(5,5′-dmbpy)2]·5DMF, 2; [Mn(btdc)(4,4;-dmbpy)], 3; [Mn2(btdc)2(bpy)(dmf)]·0.5DMF, 4; [Mn2(btdc)2(5,5′-dmbpy)(dmf)]·DMF, 5 (dmf, DMF = N,N-dimethylformamide) have been synthesized, and their crystal structure has been established using single-crystal X-ray diffraction analysis (XRD). The chemical and phase purities of Compounds 1–3 have been confirmed via powder X-ray diffraction, thermogravimetric, and chemical analyses as well as IR spectroscopy. The influence of the bulkiness of the chelating N-donor ligand on the dimensionality and structure of the coordination polymer has been analyzed, and the decrease in the framework dimensionality, as well as the secondary building unit’s nuclearity and connectivity, has been observed for bulkier ligands. For three-dimensional (3D) coordination polymer 1, the textural and gas adsorption properties have been studied, revealing noticeable ideal adsorbed solution theory (IAST) CO2/N2 and CO2/CO selectivity factors (31.0 at 273 K and 19.1 at 298 K and 25.7 at 273 K and 17.0 at 298 K, respectively, for the equimolar composition and the total pressure of 1 bar). Moreover, significant adsorption selectivity for binary C2–C1 hydrocarbons mixtures (33.4 and 24.9 for C2H6/CH4, 24.8 and 17.7 for C2H4/CH4, 29.3 and 19.1 for C2H2/CH4 at 273 K and 298 K, respectively, for the equimolar composition and the total pressure of 1 bar) has been observed, making it possible to separate on 1 natural, shale, and associated petroleum gas into valuable individual components. The ability of Compound 1 to separate benzene and cyclohexane in a vapor phase has also been analyzed based on the adsorption isotherms of individual components measured at 298 K. The preferable adsorption of C6H6 over C6H12 by 1 at high vapor pressures (VB/VCH = 1.36) can be explained by the existence of multiple van der Waals interactions between guest benzene molecules and the metal–organic host revealed by the XRD analysis of 1 immersed in pure benzene for several days (1≅2C6H6). Interestingly, at low vapor pressures, an inversed behavior of 1 with preferable adsorption of C6H12 over C6H6 (KCH/KB = 6.33) was observed; this is a very rare phenomenon. Moreover, magnetic properties (the temperature-dependent molar magnetic susceptibility, χp(T) and effective magnetic moments, μeff(T), as well as the field-dependent magnetization, M(H)) have been studied for Compounds 1–3, revealing paramagnetic behavior consistent with their crystal structure.

Polymer ion-exchange membranes are featured in a variety of modern technologies including separation, concentration and purification of gases and liquids, chemical and electrochemical synthesis, and hydrogen power generation. In addition to transport properties, the strength, elasticity, and chemical stability of such materials are important characteristics for practical applications. Perfluorosulfonic acid (PFSA) membranes are characterized by an optimal combination of these properties. Today, one of the most well-known practical applications of PFSA membranes is the development of fuel cells. Some disadvantages of PFSA membranes, such as low conductivity at low humidity and high temperature limit their application. The approaches to optimization of properties are modification of commercial PFSA membranes and polymers by incorporation of different additive or pretreatment. This review summarizes the approaches to their modification, which will allow the creation of materials with a different set of functional properties, differing in ion transport (first of all proton conductivity) and selectivity, based on commercially available samples. These approaches include the use of different treatment techniques as well as the creation of hybrid materials containing dopant nanoparticles. Modification of the intrapore space of the membrane was shown to be a way of targeting the key functional properties of the membranes.

A new metal-organic framework (MOF) [Co 3 (btdc) 3 (5,5′-dmbpy) 2 ] • 5DMF ( 1 ) (H 2 btdc is 2,2′-bithiophene-5,5′-dicarboxylic acid and 5,5′-dmbpy is 5,5′-dimethyl-2,2′-bipyridyl) was synthesized. Compound 1 contains trinuclear secondary building blocks connected to each other by the btdc 2− ligand to form a layered coordination polymer with a free accessible volume of 36%.

The development of phosphorylated polybenzimidazoles (PBI) for high-temperature polymer–electrolyte membrane (HT-PEM) fuel cells is a challenge and can lead to a significant increase in the efficiency and long-term operability of fuel cells of this type. In this work, high molecular weight film-forming pre-polymers based on N1,N5-bis(3-methoxyphenyl)-1,2,4,5-benzenetetramine and [1,1′-biphenyl]-4,4′-dicarbonyl dichloride were obtained by polyamidation at room temperature for the first time. During thermal cyclization at 330–370 °C, such polyamides form N-methoxyphenyl substituted polybenzimidazoles for use as a proton-conducting membrane after doping by phosphoric acid for H2/air HT-PEM fuel cells. During operation in a membrane electrode assembly at 160–180 °C, PBI self-phosphorylation occurs due to the substitution of methoxy-groups. As a result, proton conductivity increases sharply, reaching 100 mS/cm. At the same time, the current-voltage characteristics of the fuel cell significantly exceed the power indicators of the commercial BASF Celtec® P1000 MEA. The achieved peak power is 680 mW/cm2 at 180 °C. The developed approach to the creation of effective self-phosphorylating PBI membranes can significantly reduce their cost and ensure the environmental friendliness of their production.

Adsorption and separation of light saturated hydrocarbons (methane, ethane and propane) as main components of natural gas on a series of isoreticular mesopomus metal-organic frameworks NIIC-20-G (G = ethyleneglycol, 1,2-propyleneglycol, 1,2-butyleneglycol, 1,2-pentylenglycol, glycerol) has been thoroughly investigated. An impact of the size and nature of the glycol moiety on fundamental parameters of the adsorption (gas uptakes, adsorption constants, enthalpy and entropy, adsorption selectivity factors) was revealed and rationalized. The highest gas uptakes at 1 bar and 298 K are 13.2 ml(STP).g(-1 )for CH4, 55.0 ml(STP).g(-1) for C2H6 and 125.4 ml (STP).g(-1) for C3H8. The IAST adsorption selectivities at ambient conditions (298 K, 1:1 gas mixture) reach 24.2 for C2H6/CH4, 29.0 for C3H8/C2H6 and as high as 1110 for C3H8/CH4. A rare combination of high adsorption uptakes and superb adsorption selectivity values achieved for NIIC-20-G put those MOFs ahead of the most other materials for light saturated hydrocarbon adsorption and separation. Dynamic breakthrough gas separation experiments on NIIC-20-Pr fully confirm effective separation of lighter alkanes from the corresponding binary or ternary mixtures. The obtained methane productivities are 1182 ml(STP).g(-1) (52.8 mol.kg(-1)) for C2H6/CH4, and 4193 ml(STP).g(-1) (187.3 mol.kg(-1)) for C3H8/CH4 equimolar gas mixtures, which greatly surpass earlier published data. The ethane productivity for an equimolar C3H8/C2H6 gas mixture is 3009 ml(STP).g(-1) (134.4 mol.kg(-1)). The breakthrough separation experiments validate a remarkable performance of the studied MOFs in the practical separation of natural gas or other relevant mixtures of light alkanes to valuable individual components.

Два новых металл-органических координационных полимера [Sr(ttdc)(dma)2] (1) и [Zn(ttdc)(bpy)]·DMA·4H2O (2) (H2ttdc = тиено[3,2-b]тиофен-2,5-дикарбоновая кислота, bpy = 2,2'-бипиридил, DMA = N,N-диметилацетамид) получены в сольватотермальных условиях. Структуры соединений установлены с помощью монокристального рентгеноструктурного анализа. Координационные полимеры охарактеризованы методами рентгенофазового, элементного, термогравиметрического анализа и ИК спектроскопии. Соединение 1 представляет собой двумерный координационный полимер, а соединение 2 — зигзагообразные цепочки, связанные за счет π—π стекинга между молекулами bpy в супрамолекулярный пористый каркас со свободным объемом 42 %.

Polybenzimidazoles (PBI) doped with phosphoric acid (PA) are promising electrolytes for medium temperature fuel cells. Their significant disadvantage is a partial or complete loss of mechanical properties and an increase in hydrogen permeability at elevated temperatures. Covalent silanol crosslinking is one possible way to stabilize PBI membranes in the presence of PA. Three organo-substituted silanes, namely (3-Bromopropyl)trimethoxysilane (SiBr), trimethoxy [2-(7-oxabicyclo [4.1.0]hept-3-yl)ethyl]silane (Si-biC) and (3-Glycidyloxypropyl)trimethoxysilane (KH 560), were used as covalent crosslinkers of PBI-O-PhT in order to determine the effect of the silane structure and crosslinking degree on membrane properties. The crosslinking degree was 1–50%. All crosslinked membranes were characterized by impedance and IR-spectroscopy. The mechanical properties, morphology, stability and hydrogen permeability of the membranes were determined. In the case of silanes with linear substituents (SiBr, KH 560), a denser structure is formed, which is characterized by greater oxidative stability and lower hydrogen permeability in comparison to the silane with a bulk group. All the crosslinked membranes have a higher mechanical strength compared with the initial PBI-O-PhT membrane both before and after doping with PA. Despite the hardening of the polymer matrix of the membranes, their proton conductivity changes insignificantly. It was shown that cross-linked membranes can be used in fuel cells.