Computational screening of metal-organic frameworks for large-molecule chemical sensing.

Grand canonical Monte Carlo simulations were performed to identify trends in low-pressure adsorption of a broad range of organic molecules by a set of metal-organic frameworks (MOFs). While previous simulation studies focused on the adsorption of small molecules such as carbon dioxide and methane, we consider more complicated organic molecules relevant to chemical sensing and detection: small aromatics (o-, m-, and p-xylene), polycyclic aromatic hydrocarbons (naphthalene, anthracene, phenanthrene), explosives (TNT and RDX), and chemical warfare agents (GA and VM). The framework materials include several Zn-IRMOFs (IRMOFs 1-3, 7, 8), a Cr-MOF (CrMIL-53lp), and a Cu-MOF (HKUST-1).

Nanoconfined water in magnesium-rich 2:1 phyllosilicates.

Inelastic neutron scattering, density functional theory, ab initio molecular dynamics, and classical molecular dynamics were used to examine the behavior of nanoconfined water in palygorskite and sepiolite. These complementary methods provide a strong basis to illustrate and correlate the significant differences observed in the spectroscopic signatures of water in two unique clay minerals. Distortions of silicate tetrahedra in the smaller-pore palygorskite exhibit a limited number of hydrogen bonds having relatively short bond lengths.

Control of vertex geometry, structure dimensionality, functionality, and pore metrics in the reticular synthesis of crystalline metal-organic frameworks and polyhedra.

Metal-organic polyhedra and frameworks (MOPs and MOFs) were prepared by linking square units M2(CO2)4 (M = Cu and Zn) with a variety of organic linkers designed to control the dimensionality (periodicity) and topology of the resulting structures. We describe the preparation, characterization, and crystal structures of 5 new MOPs and 11 new MOFs (termed MOP-14, -15, -17, -23, -24 and MOF-114, -115, -116, -117, -118, -119, -222, -601, -602, -603, -604) and show how their structures are related to the shape and functionality of the building blocks. The gas uptake behaviors of MOP-23 and MOF-601 to -603 are also presented as evidence that these structures have permanent porosity and rigid architectures.

Molecular dynamics studies of nanoconfined water in clinoptilolite and heulandite zeolites.

The complete periodic series of alkali and alkaline earth cation variants (Li(+), Na(+), K(+), Rb(+), Cs(+), Mg(2+), Ca(2+), Sr(2+), and Ba(2+)) of clinoptilolite (Si : Al=5) and heulandite (Si : Al=3.5) aluminosilicate zeolites are examined by large-scale molecular dynamics utilizing a flexible SPC water and aluminosilicate force field. Calculated hydration enthalpies, radial distribution functions, and ion coordination environments are used to describe the energetic and structural components of extra-framework species while power spectra are used to examine the intermolecular dynamics.

Vanadium complex of 2-(2'-Pyridyl)-4,5-dicyanoimidazole showing spermicidal and cytotoxic properties.

Two complexes having the formulas VO(DCIPy)2(H2O).1.5H2O and VO(DCIPy)2(H2O).

Nitrogen-atom exchange mediated by nitrido complexes of molybdenum.

Nitrido complexes NMo(OC(CF3)2Me)3 and NMo(OC(CF3)3)3(NCMe) containing fluorinated alkoxide ancillary ligands are synthesized in 57% and 50% yield, respectively. Both complexes undergo N-atom exchange within hours at 30 degrees C with acetonitrile and benzonitrile in either THF-d8 or CD2Cl2, as shown by 15N NMR studies using labeled 15NCMe. In both solvents, is the more active in this process.

Porous, crystalline, covalent organic frameworks.

Covalent organic frameworks (COFs) have been designed and successfully synthesized by condensation reactions of phenyl diboronic acid {C6H4[B(OH)2]2} and hexahydroxytriphenylene [C18H6(OH)6]. Powder x-ray diffraction studies of the highly crystalline products (C3H2BO)6.(C9H12)1 (COF-1) and C9H4BO2 (COF-5) revealed expanded porous graphitic layers that are either staggered (COF-1, P6(3)/mmc) or eclipsed (COF-5, P6/mmm).

Design, synthesis, structure, and gas (N2, Ar, CO2, CH4, and H2) sorption properties of porous metal-organic tetrahedral and heterocuboidal polyhedra.

A strategy based on assembling metal ions and organic carboxylate links has been applied for the design and synthesis of a new class of porous, truncated tetrahedral and heterocuboidal polyhedra, whose pore size and functionality can be systematically varied. The synthesis of this series of metal-organic polyhedra (MOPs) employs sulfate-capped oxygen-centered iron-carboxylate trimers, Fe3O(CO2)3(-)(SO4)3, as rigid nodes separated by linear (phenyl, biphenyl, terphenyl, and tetrahydropyrene) or trigonal (benzenetriphenyl) links to yield five highly crystalline polyhedra of general formula [NH2(CH3)2]8[Fe12O4(-)(SO4)12(link)x(py)12].G (x = 6 for linear or 4 for trigonal, py = pyridine, G = guests).

Reticular chemistry: occurrence and taxonomy of nets and grammar for the design of frameworks.

The structures of all 1127 three-periodic extended metal-organic frameworks (MOFs) reported in the Cambridge Structure Database have been analyzed, and their underlying topology has been determined. It is remarkable that among the almost infinite number of net topologies that are available for MOFs to adopt, only a handful of nets are actually observed. The discovery of this inversion between expected and observed nets led us to deduce a system of classification "taxonomy" for interpreting and rationalizing known MOF structures, as well as those that will be made in future.

Transformation of a metal-organic framework from the NbO to PtS net.

Two metal-organic frameworks (MOFs), MOF-501 and MOF-502, respectively, formulated as Co(2)(BPTC)(H(2)O)(5).G(x) and Co(2)(BPTC)(H(2)O)(DMF)(2).G(x) (BPTC = 3,3',5,5'-biphenyltetracarboxylate; G = guest molecules), have been synthesized and structurally characterized, and their topologies were found to be based on the NbO (MOF-501) and PtS (MOF-502) nets.

Reticular synthesis and the design of new materials.

The long-standing challenge of designing and constructing new crystalline solid-state materials from molecular building blocks is just beginning to be addressed with success. A conceptual approach that requires the use of secondary building units to direct the assembly of ordered frameworks epitomizes this process: we call this approach reticular synthesis. This chemistry has yielded materials designed to have predetermined structures, compositions and properties.