Showing papers by "Mohamed Eddaoudi published in 2012"

Templated Synthesis, Postsynthetic Metal Exchange, and Properties of a Porphyrin-Encapsulating Metal–Organic Material

Abstract: Reaction of biphenyl-3,4′,5-tricarboxylate (H3BPT) and CdCl2 in the presence of meso-tetra(N-methyl-4-pyridyl)porphine tetratosylate (TMPyP) afforded porph@MOM-10, a microporous metal–organic material containing CdTMPyP cations encapsulated in an anionic Cd(II) carboxylate framework, [Cd6(BPT)4Cl4(H2O)4]. Porph@MOM-10 is a versatile platform that undergoes exchange to serve as the parent of a series of porph@MOMs that exhibit permanent porosity and heterogeneous catalytic activity.

Template-Directed Synthesis of Nets Based upon Octahemioctahedral Cages That Encapsulate Catalytically Active Metalloporphyrins

Abstract: meso-Tetra(N-methyl-4-pyridyl)porphine tetratosylate (TMPyP) templates the synthesis of six new metal–organic materials by the reaction of benzene-1,3,5-tricarboxylate with transition metals, five of which exhibit HKUST-1 or tbo topology (M = Fe, Mn, Co, Ni, Mg). The resulting materials, porph@MOMs, selectively encapsulate the corresponding metalloporphyrins in octahemioctahedral cages and can serve as size-selective heterogeneous catalysts for oxidation of olefins.

Highly Monodisperse MIII-Based soc-MOFs (M = In and Ga) with Cubic and Truncated Cubic Morphologies

Abstract: In this work, we carry out an investigation on shape-controlled growth of InIII- and GaIII-based square-octahedral metal–organic frameworks (soc-MOFs). In particular, controllable crystal morphological evolution from simple cubes to complex octadecahedra has been achieved, and resultant highly uniform crystal building blocks promise new research opportunities for preparation of self-assembled MOF materials and related applications.

On demand: the singular rht net, an ideal blueprint for the construction of a metal-organic framework (MOF) platform.

Abstract: The need for tunable functional solid-state materials is ever increasing because of the growing demand to address persisting challenges in global energy issues, environmental sustainability, and others. [1] It is practical and preferable for such materials to be pre-designed and constructed to contain the desired properties and specific functionalities for a given targeted application. An emerging unique class of solid-state materials, namely metal–organic frameworks (MOFs), has the desired attributes and offers great promise to unveil superior materials for many lasting challenges [2] since desired functionality can be introduced pre- and/or post-synthesis. [3] A remarkable feature of MOFs is the ability to build periodic structures with in-built functional properties using the molecular building block (MBB) approach, which utilizes pre-selected organic and inorganic MBBs, with desired function, that are judiciously chosen to possess the proper geometry, shape, and directionality required to target given underlying nets. [4]

Post-synthetic modification of porphyrin-encapsulating metal-organic materials by cooperative addition of inorganic salts to enhance CO2/CH4 selectivity.

Abstract: Keeping MOM: Reaction of biphenyl-3,4',5-tricarboxylate and Cd(NO3)2 in the presence of meso-tetra(N-methyl-4-pyridyl)porphine tetratosylate afforded porph@MOM-11, a microporous metal–organic material (MOM) that encapsulates cationic porphyrins and solvent in alternating open channels. Porph@MOM-11 has cation and anion binding sites that facilitate cooperative addition of inorganic salts (such as M+Cl-) in a stoichiometric fashion.

CO2 adsorption in mono-, di- and trivalent cation-exchanged metal-organic frameworks: a molecular simulation study.

Abstract: A molecular simulation study is reported for CO(2) adsorption in rho zeolite-like metal-organic framework (rho-ZMOF) exchanged with a series of cations (Na(+), K(+), Rb(+), Cs(+), Mg(2+), Ca(2+), and Al(3+)). The isosteric heat and Henry's constant at infinite dilution increase monotonically with increasing charge-to-diameter ratio of cation (Cs(+) < Rb(+) < K(+) < Na(+) < Ca(2+) < Mg(2+) < Al(3+)). At low pressures, cations act as preferential adsorption sites for CO(2) and the capacity follows the charge-to-diameter ratio. However, the free volume of framework becomes predominant with increasing pressure and Mg-rho-ZMOF appears to possess the highest saturation capacity. The equilibrium locations of cations are observed to shift slightly upon CO(2) adsorption. Furthermore, the adsorption selectivity of CO(2)/H(2) mixture increases as Cs(+) < Rb(+) < K(+) < Na(+) < Ca(2+) < Mg(2+) ≈ Al(3+). At ambient conditions, the selectivity is in the range of 800-3000 and significantly higher than in other nanoporous materials. In the presence of 0.1% H(2)O, the selectivity decreases drastically because of the competitive adsorption between H(2)O and CO(2), and shows a similar value in all of the cation-exchanged rho-ZMOFs. This simulation study provides microscopic insight into the important role of cations in governing gas adsorption and separation, and suggests that the performance of ionic rho-ZMOF can be tailored by cations.

Understanding hydrogen sorption in a polar metal-organic framework with constricted channels.

Abstract: A high fidelity molecular model is developed for a metal-organic framework (MOF) with narrow (approximately 7.3 A) nearly square channels. MOF potential models, both with and neglecting explicit polarization, are constructed. Atomic partial point charges for simulation are derived from both fragment-based and fully periodic electronic structure calculations. The molecular models are designed to accurately predict and retrodict material gas sorption properties while assessing the role of induction for molecular packing in highly restricted spaces. Thus, the MOF is assayed via grand canonical Monte Carlo (GCMC) for its potential in hydrogen storage. The confining channels are found to typically accommodate between two to three hydrogen molecules in close proximity to the MOF framework at or near saturation pressures. Further, the net attractive potential energy interactions are dominated by van der Waals interactions in the highly polar MOF – induction changes the structure of the sorbed hydrogen but not the MOF storage capacity. Thus, narrow channels, while providing reasonably promising isosteric heat values, are not the best choice of topology for gas sorption applications from both a molecular and gravimetric perspective.

Heterocyclic macrocycle templated metal-organic materials

Abstract: A process for the preparation of a heterocyclic macrocycle-templated supramolecular metal organic material, the process comprising preparing a reaction mixture containing a metal, a heterocyclic macrocycle, and organic ligands and forming, in the reaction mixture, a heterocyclic macrocycle-templated metal organic material comprising the metal, the heterocyclic macrocycle and the ligands by template-directed synthesis with the heterocyclic macrocycle serving as the template and being encapsulated within a cage of the template metal organic material.

Metal organic materials as biomimetic enzymes

Abstract: A supramolecular assembly comprising a metal-organic molecular framework and a heterocyclic macrocycle guest molecule. The metal-organic molecular framework comprises cubicuboctahedral cavities, octahemioctahedral cavities and trigonal cavities in a 1:1:2 ratio, respectively, and the heterocyclic macrocycle guest molecule is hosted by the octahemioctahedral cavity. In a preferred embodiment, the heterocyclic macrocycle guest molecule is a heme.

Zeolitelike Metal–Organic Frameworks (ZMOFs): Design, Structure, and Properties

Abstract: The quest for functional materials targeted at specific applications is ever increasing as societal needs and demands mount with advancing technology. One class of inorganic-organic hybrid materials, metal-organic materials (MOMs), has burgeoned in recent years due, in part, to effective design strategies (e.g., reticular chemistry) for their synthesis and their inherent (and readily interchangeable) hybrid, highly functional character. The molecular building block (MBB) approach introduces the ability to generate rigid and directional building blocks, mostly in situ, for the construction of MOMs having specific underlying networks and/or targeted functions/properties. Various MBBs can be targeted and utilized in the assembly of functional MOMs: (i) single-metal-ion-based MBBs, which promote rational construction, by forcing rigidity and directionality through control of the metal coordination sphere and judicious selection of suitable heterofunctional (N-, O-coordination) organic ligands, of porous MOMs with extralarge cavities, including zeolitelike metal-organic frameworks (ZMOFs); (ii) multinuclear metal-cluster-based MBBs, where, for example, simple metal-carboxylate clusters possess multiple metal-oxygen coordination bonds that result in the generation of rigid nodes with fixed geometry that, when combined with organic ligands of specific geometry, lead to the construction of desired MOMs; and (iii) supermolecular building blocks (SBBs), which involve enhanced built-in directional and structural information (e.g., high degree of symmetry and connectivity) compared to simple MBBs and allow the construction of high-connectivity nets (e.g., rht-MOFs). The MBB approach and associated strategies, as well as physical properties of some corresponding MOMs, are presented. Keywords: metal-organic frameworks; zeolite-like MOFs; molecular building block approach; hybrid porous solids; supermolecular building blocks; catalyst encapsulation; crystal chemistry; MOF platforms