Proton-exchange membrane fuel cells are an attractive green technology for energy production. However, one of their major drawbacks is instability of the electrolytes under working conditions (i.e.
View Article and Find Full Text PDFPorous robust materials are typically the primary selection of several industrial processes. Many of these compounds are, however, not robust enough to be used as multifunctional materials. This is typically the case of Metal-Organic Frameworks (MOFs) which rarely combine several different excellent functionalities into the same material.
View Article and Find Full Text PDFProton exchange membrane fuel cells (PEMFCs) are an attractive green technology for energy generation. The poor stability and performances under working conditions of the current electrolytes are their major drawbacks. Metal-Organic Frameworks (MOFs) have recently emerged as an alternative to overcome these issues.
View Article and Find Full Text PDFA new robust Bi-carboxylate metal-organic framework (MOF) IEF-2 was hydrothermally prepared, acting as a proton carrier (σ∼ 1.1 × 10 S cm). Such proton conductivity is among the highest reported so far for purely 3D carboxylate-based MOFs, being explained by the existence of a 1D hydrogen-bond network, as suggested by structural analysis and theoretical studies.
View Article and Find Full Text PDFHierarchical porous UiO-66-NH2 cm-monolithic xero- and aero-gels with a controlled shape and mechanical robustness were successfully produced from ethanolic gels. Their remarkable controlled hierarchical porosity was effectively assessed using N2 sorption, Hg intrusion porosimetry and focused ion beam-scanning electron microscopy methods.
View Article and Find Full Text PDFThe three-dimensional (3D) microporous titanium aminoterephthalate MIL-125-NH₂ (MIL: Material of Institut Lavoisier) was successfully isolated as monodispersed nanoparticles, which are compatible with intravenous administration, by using a simple, safe and low-cost synthetic approach (100 °C/32 h under atmospheric pressure) so that for the first time it could be considered for encapsulation and the release of drugs. The nerve agent antidote 2-[(hydroxyimino)methyl]-1-methyl-pyridinium chloride (2-PAM or pralidoxime) was effectively encapsulated into the pores of MIL-125-NH₂ as a result of the interactions between 2-PAM and the pore walls being mediated by π-stacking and hydrogen bonds, as deduced from infrared spectroscopy and Monte Carlo simulation studies. Finally, colloidal solutions of MIL-125-NH₂ nanoparticles exhibited remarkable stability in different organic media, aqueous solutions at different pH and under relevant physiological conditions over time (24 h).
View Article and Find Full Text PDFPhosphonate- and yttrium-based metal-organic frameworks (MOFs), formulated as [Y(Hbtp)]·5.5HO (1), [Y(Hbtp)]·2.5HO (2), (HO)[Y(Hbtp)(Hbtp)]·HO (3), and [Y(Hbtp)]·HO·0.
View Article and Find Full Text PDFAfter three decades of intense and fundamental research on metal-organic frameworks (MOFs), is there anything left to say or to explain? The synthesis and properties of MOFs have already been comprehensively described elsewhere. It is time, however, to prove the nature of their true usability: technological applications based on these extended materials require development and implementation as a natural consequence of the up-to-known intensive research focused on their design and preparation. The current large number of reviews on MOFs emphasizes practical strategies to develop novel networks with varied crystal size, shape and topology, being mainly devoted to academic concerns.
View Article and Find Full Text PDFActa Crystallogr B Struct Sci Cryst Eng Mater
February 2014
Three new crystalline metal-organic frameworks have been prepared from the reaction of uranyl nitrate with nitrilotris(methylphosphonic acid) [H6nmp, N(CH2PO3H2)3], 1,4-phenylenebis(methylene)diphosphonic acid [H4pmd, C6H4(PO3H2)2], and (benzene-1,3,5-triyltris(methylene))triphosphonic acid [H6bmt, C6H3(PO3H2)3]. Compound [(UO2)2F(H3nmp)(H2O)]·4H2O (I) crystallizes in space group C2/c, showing two crystallographically independent uranyl centres with pentagonal bipyramidal coordination geometries. While one metal centre is composed of a {(UO2)O3(μ-F)}2 dimer, the other comprises an isolated {(UO2)O5} polyhedron.
View Article and Find Full Text PDFA rapid, mild and high-yield microwave synthesis of 1D isotypical [Ln(H4bmt)(H5bmt)(H2O)2]·3H2O coordination polymers is presented. The La(3+)-based material is highly active as a heterogeneous catalyst in the methanolysis of styrene oxide at nearly room temperature. Eu(3+)- and Tb(3+)-doped materials are very effective UV-to-visible light converters.
View Article and Find Full Text PDFThe title compound, C(48)H(20)F(19)N(4)O(3)P, prepared by the nucleophilic attack of triethyl phosphite on one of the 4-fluoro atoms of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin, contains a single molecule in the asymmetric unit. The porphyrin unit is almost planar [largest non-H atom deviation = 0.174 (6) Å], and has the planes of the neighbouring benzene rings oriented at angles ranging from 64.
View Article and Find Full Text PDFMetal-organic frameworks (MOFs), also known as coordination polymers, are formed by the self-assembly of metallic centres and bridging organic linkers. In this critical review, we review the key advances in the field and discuss the relationship between the nature and structure of specifically designed organic linkers and the properties of the products. Practical examples demonstrate that the physical and chemical properties of the linkers play a decisive role in the properties of novel functional MOFs.
View Article and Find Full Text PDFThe asymmetric unit of the title compound, C(9)H(9)Br(3), is composed of a single molecule. Two bromo substituents are located on one side of the plane of the aromatic ring and the third is on the opposite side, with the molecular unit exhibiting an approximate noncrystallographic C(s) point group. The crystal structure is rich in Br.
View Article and Find Full Text PDFActa Crystallogr Sect E Struct Rep Online
November 2010
The title compound, C(12)H(18)N(6)O(6), was synthesized via nucleophilic substitution by reacting 2,4,6-trichloro-1,3,5-triazine with glycine methyl ester hydro-chloride in reflux (dried toluene) under anhydrous atmosphere. Individual mol-ecules self-assemble via strong N-H⋯O hydrogen bonds into supra-molecular double tapes running parallel to the [010] crystallographic direction. The close packing of supra-molecular tapes is mediated by geometrical reasons in tandem with a number of weaker N-H⋯O and C-H⋯N hydrogen-bonding inter-actions.
View Article and Find Full Text PDFThe title compound, C(3)H(10)NO(3)P, crystallizes in its zwitterionic form, H(3)N(+)CH(C(2)H(5))PO(O(-))(OH), with the asymmetric unit being composed by two of such entities (Z' = 2). The crystal packing leads to a sequence of hydro-phobic and hydro-philic layers. While the hydro-phobic layer comprises the aliphatic substituent groups, the hydro-philic one is held together by a series of strong and rather directional N(+)-H⋯O and O-H⋯O hydrogen bonds.
View Article and Find Full Text PDFThe title compound, C(2)H(8)NO(3)P, crystallizes in its zwitterionic form H(3)N(+)CH(CH(3))PO(O(-))(OH). In the crystal, the molecules are linked by N-H⋯O and O-H⋯O hydrogen bonds.
View Article and Find Full Text PDFActa Crystallogr Sect E Struct Rep Online
July 2009
The title compound, C(6)H(6)Cl(2)N(4)O(2), was prepared by the nucleophilic substitution of 2,4,6-trichloro-1,3,5-triazine by glycine methyl ester hydro-chloride, and was isolated from the reaction by using flash chromatography. The crystal structure at 150 K reveals the presence two crystallographically independent mol-ecules in the asymmetric unit which differ in the orientation of the pendant methoxy-carbonyl group. Each mol-ecular unit is engaged in strong and highly directional N-H⋯N hydrogen-bonding inter-actions with a symmetry-related mol-ecule, forming supra-molecular dimers which act as the synthons in the crystal packing.
View Article and Find Full Text PDFTHE TITLE COMPOUND [SYSTEMATIC NAME: (methoxy-carbonyl-meth-yl)ammonium chloride], crystallizes as a salt, C(3)H(8)NO(2) (+)·Cl(-), with the charged species inter-acting mutually via strong and highly directional N(+)-H⋯Cl(-) hydrogen bonds which lead to the formation of a supra-molecular tape running parallel to the c axis. Tapes close pack in the solid state mediated by multipoint recognition synthons based on weak C-H⋯O inter-actions and van der Waals contacts between adjacent methyl groups.
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