A homochiral metal-organic framework membrane for enantioselective separation

For the first time, a homochiral metal-organic framework membrane was prepared for the enantioselective separation of important chiral compounds, especially chiral drug intermediates, which will allow for the potential development of a new, sustainable and highly efficient chiral separation technique.     

Enantioselective sorption of alcohols in a homochiral metal-organic framework

Single-crystal X-ray diffraction study reveals the host-guest interactions between a homochiral metal-organic framework and two enantiomers of a chiral alcohol providing the key driving force for the enantioselective sorption of alcohols in the framework.     

A homochiral porous metal-organic framework for highly enantioselective heterogeneous asymmetric catalysis

A homochiral porous noninterpenetrating metal-organic framework (MOF), 1, was constructed by linking infinite 1D [Cd(mu-Cl)2]n zigzag chains with axially chiral bipyridine bridging ligands containing orthogonal secondary functional groups. The secondary chiral dihydroxy groups accessible via the large open channels in 1 were utilized to generate a heterogeneous asymmetric catalyst for the addition of diethyzinc to aromatic aldehydes to afford chiral secondary alcohols at up to 93% enantiomeric excess (ee). Control experiments with dendritic aromatic aldehydes of different sizes indicate that the heterogeneous asymmetric catalyst derived from 1 is both highly active and enantioselective as a result of the creation of readily accessible, uniform active catalyst sites inside the porous MOF.     

Isoreticular homochiral porous metal-organic structures with tunable pore sizes

Chiral-layered building motifs of zinc(II) camphorate are linked through linear N-donor ligands, forming series of three-dimensional isoreticular porous homochiral frameworks. The lengths of these linear ligands control the pore sizes and free accessible volumes of the homochiral metal-organic structures.     

Single-crystal metal-organic framework arrays

A novel, versatile pen-type lithography-based methodology was developed to control the growth of HKUST-1 crystals on surfaces by direct delivery of femtoliter droplets containing both inorganic and organic building block precursors. This approach shows that through the use of surfaces with low wettability it is possible to control the crystallization of a single submicrometer metal-organic framework crystal at a desired location on a surface.     

Mesoporous metal-organic framework materials

Metal-organic frameworks (MOFs) have emerged as a new type of porous materials for diverse applications. Most open MOFs reported to date are microporous (pore sizes <2 nm), and only a small fraction of MOFs with ordered mesoscale domains (2-50 nm) is reported. This tutorial review covers recent advances in the field of mesoporous MOFs (mesoMOFs), including their design and synthesis, porosity activation and surface modification, and potential applications in storage and separation, catalysis, drug delivery and imaging. Their specificities are dependent on the pore shape, size, and chemical environments of the cages or channels. The relationship between the structures and functions is discussed. The future outlook for the field is discussed in the context of current challenges in applications of mesoporous materials.     

A designed metal-organic framework based on a metal-organic polyhedron

A C(3) symmetric ligand with three 1,3-benzenedicarboxylate units has been used to construct a metal-organic framework with a (3,24)-connected network topology, where the nanometre-sized metal-organic cuboctahedra (MOCs) have been incorporated solely into a cubic close packing (CCP) arrangement, which led to superoctahedral and supertetrahedral cavities.     

"Clickable" metal-organic framework

We demonstrated the metal-organic framework bearing the azide group in the organic linkers and in situ click reactions with some small alkynes. The XRPD patterns indicated that the click reaction proceeded without any decomposition of the original MOF network. Controlling the organic linkers and incorporation of the azide groups should provide the designer-made MOFs that have controlled molecular cavities with the desired steric dimensions and functionality.     

Hierarchically ordered homochiral metal-organic frameworks built from exceptionally large rectangles and squares

Hierarchically ordered homochiral metal-organic frameworks were built from the Cu(II) connecting point and the new (R)-6,6'-dichloro-2,2'-diethoxy-1,1'-binaphthyl-4,4'-bis(p-ethynylpyridine) bridging ligand (L). [Cu(3)L(4)(DMF)(6)(H(2)O)(3)(ClO(4))][ClO(4)](5).10DMF.10EtOH.7H(2)O (1) adopts a unique three-dimensional framework structure via simultaneous interlocking and interpenetration of one-dimensional ladders formed by linking rectangles of 24.8 x 48.6 A(2) in dimensions, whereas [Cu(3)L(5)(DMF)(8)][ClO(4)](6).6DMF.8EtOH.Et(2)O.6H(2)O (2) exhibits an interesting network topology by threading two-dimensional coordination square grids with one-dimensional coordination polymers.     

Ionothermal synthesis of homochiral framework with acetate-pillared cobalt-camphorate architecture

A new organically templated homochiral material (EMIm)[Co 2( d-cam) 2(ac)] ( 1; d-H 2cam = d-camphoric acid; ac = acetate; EMIm = 1-ethyl-3-methylimidazolium) has been ionothermally synthesized, and it features an unusual acetate-pillared cobalt-camphorate architecture encapsulating the cationic component of the ionic liquid.     

A luminescent mixed-lanthanide metal-organic framework thermometer

A luminescent mixed lanthanide metal-organic framework approach has been realized to explore luminescent thermometers. The targeted self-referencing luminescent thermometer Eu(0.0069)Tb(0.9931)-DMBDC (DMBDC = 2, 5-dimethoxy-1, 4-benzenedicarboxylate) based on two emissions of Tb(3+) at 545 nm and Eu(3+) at 613 nm is not only more robust, reliable, and instantaneous but also has higher sensitivity than the parent MOF Tb-DMBDC based on one emission at a wide range from 10 to 300 K.     

Two luminescent enantiomorphic 3D metal-organic frameworks with 3D homochiral double helices

Two enantiomorphic Cd(II) coordination polymers with three-dimensional homochiral double helices have been assembled respectively from two tripodal enantiopure amino acid derivatives, which exhibit (3,4)-connected (6(3))(6(3).10(3)) topology and strong purple fluorescence.     

Flexible and hydrophobic Zn-based metal-organic framework

A zinc-based metal-organic framework Zn(2)(adb)(2)(dabco)·4.5 DMF (K) (DUT-30(Zn), DUT = Dresden University of Technology, adb = 9,10-anthracene dibenzoate, dabco =1,4-diazabicyclo[2.2.2]octane, DMF = N,N-dimethylformamide) was synthesized using a solvothermal route. This MOF exhibits six crystallographic guest dependent phases. Two of them were characterized via single crystal X-ray analysis. The as-synthesized phase K crystallizes in the orthorhombic space group Fmmm, with a = 9.6349(9), b = 26.235(3), and c = 28.821(4) ? and consists of two interpenetrated pillar-layer networks with pcu topology. When the substance loses 0.5 DMF molecules per formula unit, a phase transition from the kinetic phase K to a thermodynamic phase T occurs. Zn(2)(adb)(2)(dabco)·4 DMF (T) crystallizes in the tetragonal space group I4/mmm, with a = 19.5316(8) and c = 9.6779(3) ?. During the evacuation the DUT-30(Zn) undergoes again the structural transformation to A. The activated compound A shows the gate pressure effect in the low pressure region of nitrogen physisorption isotherm and has a BET surface area of 960 m(2 )g(-1) and a specific pore volume of 0.43 cm(3) g(-1). Furthermore, DUT-30(Zn) exhibits a hydrogen storage capacity of 1.12 wt % at 1 bar, a CO(2) uptake of 200 cm(3) g(-1) at -78 °C and 0.9 bar, and a n-butane uptake of 3.0 mmol·g(-1) at 20 °C. The N(2) adsorption process was monitored in situ via X-ray powder diffraction using synchrotron radiation. A low temperature induced transformation of phase A to phase V could be observed if the compound was cooled under vacuum to -196 °C. A further crystalline phase N could be identified if the framework was filled with nitrogen at -196 °C. Additionally, the treatment of activated phase A with water leads to the new phase W.     

Open metal-organic framework containing cuprate chains

A three-dimensional Cu(II) metal-organic framework, copper hydroxide p-pyridinecarboxylate hydrate, [Cu(OH)(C5H4NCO2).H2O], was synthesized by hydrothermally reacting copper nitrate with p-pyridinecarboxylic acid. The crystals were suitable for single-crystal X-ray diffraction analysis, which showed that the Cu(II) centers adopt a slightly distorted square pyramidal geometry. They coordinate to both the pyridyl and carboxylate functionalities of the pyridinecarboxylate bridging ligands. Infinite copper oxide chains run through the structure and are connected by p-pyridinecarboxylate (p-PyC) ligands. Crystal data: monoclinic, space group P2(1)/n, a = 3.5521(2) A, b = 15.8665(11) A, c = 12.9977(9) A, beta = 95.285(2) degrees , and Z = 4. Thermogravimetric analysis (TGA) revealed that the guest H2O molecules in the channels may be removed, and the material is stable to ca. 245 degrees C. Magnetic measurements indicated the material has one-dimensional (1D) antiferromagnetic ordering within the Cu2+ chains with a Néel temperature of ca. 51 K. Data fitting to the Bonner-Fisher model yielded a coupling constant, J, of -7.3 cm(-1) and g factor of 2.15. The Curie tail below 20 K is due to a small amount of paramagnetic impurities, calculated to be approximately 0.2% in concentration. Further characterization of crystallinity and morphology are discussed, including powder X-ray diffraction (PXRD), elemental analysis, and optical microscopy.     

Nanoreactors derived from silica-protection-assisted metal-organic framework

The construction of highly stable and regular nanoreactors is a major challenge. In this work, we use a facile template protection method to obtain ZIF-67@SiO₂ (JS) and to encapsulate metal oxide nanoparticles (Co₃O₄) into nanoreactors (SiO₂). ZIF-67 crystals provide a cobalt species; SiO₂ was first used as a protective layer of ZIF-67 and then as a nanoreactor for metastable metal oxide nanoparticles. On this basis, Co₃O₄@SiO₂ with dodecahedron morphology were synthesized by calcining JS at different temperatures, followed by a hydrothermal reaction to obtain Co₃(OH)₄Si₂O₅. Subsequently, CoS_x and CoP-SiO₂ were fabricated through sulfuration and phosphorization. The results in this work show that nanoreactors derived from metal-organic frameworks (MOFs) with a rational structure have broad development prospects.