Showing papers by "Mohamed Eddaoudi published in 1999"

Design and synthesis of an exceptionally stable and highly porous metal-organic framework

Abstract: Open metal–organic frameworks are widely regarded as promising materials for applications1,2,3,4,5,6,7,8,9,10,11,12,13,14,15 in catalysis, separation, gas storage and molecular recognition. Compared to conventionally used microporous inorganic materials such as zeolites, these organic structures have the potential for more flexible rational design, through control of the architecture and functionalization of the pores. So far, the inability of these open frameworks to support permanent porosity and to avoid collapsing in the absence of guest molecules, such as solvents, has hindered further progress in the field14,15. Here we report the synthesis of a metal–organic framework which remains crystalline, as evidenced by X-ray single-crystal analyses, and stable when fully desolvated and when heated up to 300?°C. This synthesis is achieved by borrowing ideas from metal carboxylate cluster chemistry, where an organic dicarboxylate linker is used in a reaction that gives supertetrahedron clusters when capped with monocarboxylates. The rigid and divergent character of the added linker allows the articulation of the clusters into a three-dimensional framework resulting in a structure with higher apparent surface area and pore volume than most porous crystalline zeolites. This simple and potentially universal design strategy is currently being pursued in the synthesis of new phases and composites, and for gas-storage applications.

From Condensed Lanthanide Coordination Solids to Microporous Frameworks Having Accessible Metal Sites

Abstract: The combination of terbium nitrate and 1,4-benzenedicarboxylic acid (H2BDC) in the presence of triethylamine yields the compound Tb2(BDC)3·(H2O)4, which has an extended nonporous structure constructed from copolymerized BDC and Tb(III) units. The multidentate functionality of BDC and the tendency of Tb to have a high coordination number has allowed water to act as a terminal ligand to Tb in the structure. Upon thermally liberating the water ligands, a microporous material, Tb2(BDC)3, is achieved, which has extended 1-D channels and the same framework structure as that of the as-synthesized solid as evidenced by XRPD. Water sorption isotherm data proves that Tb2(BDC)3 has permanent microporosity, and points to the presence of accessible metal sites within the pores, which also allows the sorption of ammonia to give Tb2(BDC)3·(NH3)4. Luminescence lifetime measurements confirm that resorbed water and sorbed ammonia are bound to Tb and that they give distinctly different decay constants.

A Microporous Lanthanide-Organic Framework.

Abstract: Stable zeolite-like microporosity, even in the absence of guest molecules, is exhibited by a lanthanide-benzenedicarboxylate (BDC) framework, which was synthesized by the copolymerization of Tb(III) and 1,4-benzenedicarboxylic acid. The open Tb-BDC framework adopts an expanded PtS network structure (see diagram; Tb: open circles; C: full circles; lines connecting Tb to C represent O atoms, and those connecting C atoms are benzene rings) and is capable of reversible gas and liquid sorption.

Design and synthesis of metal-carboxylate frameworks with permanent microporosity

Abstract: Metal-carboxylate clusters are ideally suited as secondary building units (SBU) for the assembly of extended open frameworks. Examples extracted from the chemistry of the multidentate building block 1,4-benzenedicarboxylate (BDC) show that Zn(BDC) clusters lead to the formation of rigid, stable and truly microporous metal-carboxylate networks. Gas sorption isotherms measured for this class of materials show type (I) gas uptake that is analogous to those observed for zeolites and molecular sieves.

An Open‐Framework Germanate with Polycubane‐Like Topology

Abstract: Body-centered Ge9 parallelepiped building blocks form the basis of the structure of [Ge9 O18 (OH)4 ]⋅2 (H2 ppz)⋅0.5 (H2 O) (ASU-14, ppz=piperazine). In this new structure type for an open-framework germanate (see picture for a section of the structure) the building blocks are linked together at each of their eight vertices to give the rare polycubane topology with an intersecting channel system of ten- and eight-membered rings (pore sizes 5×6 and 4×4 A2 , respectively) in which the piperazinium cations and water molecules reside.

Noninterpenetrating indium sulfide supertetrahedral cristobalite framework

Abstract: Realizing the synthesis and crystal structure of microporous materials with pore sizes 10--20 {angstrom} has been a formidable challenge in molecular sieve science. Access to such materials, with uniform pore size, is expected to impact the petrochemical and the life-sciences fields by providing opportunities for the size and shape-selective catalysis/separation of large molecules. In this direction, theoretical approaches to decorating specific 4-connected networks have been proposed, whereby replacing each (T1) tetrahedron, TX{sub 4}, in a given network by a larger tetrahedron (hereafter referred to as a supertetrahedron), signified Tn, yields a porous network due to the increased size of the building blocks. With large n, frameworks of unprecedented porosity could be achieved. Recognizing the potential of this approach, the authors have embarked on a program aimed at using inorganic clusters as molecular building blocks in the assembly of extended networks: The copolymerization of Mn(II) with the tetrahedral adamantine Ge{sub 4}S{sub 10}{sup 4{minus}} (T2) cluster, composed of 4 GeX{sub 4/2} tetrahedra, yielded MnGe{sub 4}S{sub 10}{center{underscore}dot}2(CH{sub 3}){sub 4}N having a porous cristobalite network with the organic cations occupying the void space.