Metal-organic frameworks (MOFs) are porous materials constructed from modular molecular building blocks, typically metal clusters and organic linkers. These can, in principle, be assembled to form an almost unlimited number of MOFs, yet materials reported to date represent only a tiny fraction of the possible combinations. Here, we demonstrate a computational approach to generate all conceivable MOFs from a given chemical library of building blocks (based on the structures of known MOFs) and rapidly screen them to find the best candidates for a specific application. From a library of 102 building blocks we generated 137,953 hypothetical MOFs and for each one calculated the pore-size distribution, surface area and methane-storage capacity. We identified over 300 MOFs with a predicted methane-storage capacity better than that of any known material, and this approach also revealed structure-property relationships. Methyl-functionalized MOFs were frequently top performers, so we selected one such promising MOF and experimentally confirmed its predicted capacity.

Microporous metal-organic frameworks (MOFs) that display permanent porosity show great promise for a myriad of purposes. The potential applications of MOFs can be developed further and extended by encapsulating various functional species (for example, nanoparticles) within the frameworks. However, despite increasing numbers of reports of nanoparticle/MOF composites, simultaneously to control the size, composition, dispersed nature, spatial distribution and confinement of the incorporated nanoparticles within MOF matrices remains a significant challenge. Here, we report a controlled encapsulation strategy that enables surfactant-capped nanostructured objects of various sizes, shapes and compositions to be enshrouded by a zeolitic imidazolate framework (ZIF-8). The incorporated nanoparticles are well dispersed and fully confined within the ZIF-8 crystals. This strategy also allows the controlled incorporation of multiple nanoparticles within each ZIF-8 crystallite. The as-prepared nanoparticle/ZIF-8 composites exhibit active (catalytic, magnetic and optical) properties that derive from the nanoparticles as well as molecular sieving and orientation effects that originate from the framework material.

We have synthesized, characterized, and computationally simulated/validated the behavior of two new metal-organic framework (MOF) materials displaying the highest experimental Brunauer-Emmett-Teller (BET) surface areas of any porous materials reported to date (~7000 m(2)/g). Key to evacuating the initially solvent-filled materials without pore collapse, and thereby accessing the ultrahigh areas, is the use of a supercritical CO(2) activation technique. Additionally, we demonstrate computationally that by shifting from phenyl groups to "space efficient" acetylene moieties as linker expansion units, the hypothetical maximum surface area for a MOF material is substantially greater than previously envisioned (~14600 m(2)/g (or greater) versus ~10500 m(2)/g).

Metal-organic frameworks--a class of porous hybrid materials built from metal ions and organic bridges--have recently shown great promise for a wide variety of applications. The large choice of building blocks means that the structures and pore characteristics of the metal-organic frameworks can be tuned relatively easily. However, despite much research, it remains challenging to prepare frameworks specifically tailored for particular applications. Here, we have used computational modelling to design and predictively characterize a metal-organic framework (NU-100) with a particularly high surface area. Subsequent experimental synthesis yielded a material, matching the calculated structure, with a high BET surface area (6,143 m(2) g(-1)). Furthermore, sorption measurements revealed that the material had high storage capacities for hydrogen (164 mg g(-1)) and carbon dioxide (2,315 mg g(-1))--gases of high importance in the contexts of clean energy and climate alteration, respectively--in excellent agreement with predictions from modelling.

Consisting of only four morphological parts, the Arabidopsis ovule is a relatively simple structure that lends itself to the study of genetic regulation of pattern formation and organogenesis in plants (for review, see Gasser and Robinson-Beers 1993;Reiser and Fischer 1993;Angenent and Colombo 1996;Gasser et al. 1998;Schneitz et al. 1998b). Although initiating as a radially symmetrical primordium, the developing ovule subsequently exhibits differences between the side toward the apex of the carpel (adaxial) and the side toward the base of the carpel (abaxial)-resulting in a bilaterally symmetrical structure. Asymmetric development is most apparent in the outer integument (one of two sheathing structures) and in the funiculus (supporting stalk). The outer integument grows extensively only on the abaxial side of the ovule, and the funiculus curves in the abaxial direction. Two genetic loci involved in asymmetric development of the outer integument have been described. In addition to effects on flower development (Schultz et al. 1991;Bowman et al. 1992), the SUPERMAN (SUP) gene is essential for suppressing adaxial growth of the outer integument (Gaiser et al. 1995), and mutations in this gene lead to nearly equal outer integument growth on both sides of the ovule. In contrast, inner no outer (ino) mutations can lead to an absence of outer integument growth on both sides of the ovule primordium, implicating INO as a positive regulator of integument growth or a determinant of polarity (Gaiser et al. 1995;Baker et al. 1997;Schneitz et al. 1997).In angiosperms, bilateral symmetry is also a common characteristic of leaves, floral organs, and often whole flowers. In these structures, bilateral symmetry results from significant differences in development between the adaxial (toward the shoot apex) and abaxial (away from the shoot apex) sides. Recently, several genes involved in establishing these abaxial-adaxial patterns have been identified. The cycloidea (cyc) and dichotoma (dich) genes of Antirrhinum majus are expressed on the adaxial sides of flowers, where they specify adaxial floral development (Luo et al. 1996). In contrast, phantastica (phan), which appears to be essential for identity of the adaxial leaf surface in this same species, is expressed throughout the leaf (Waites et al. 1998), and must, therefore, require additional asymmetrically distributed factors for its activity.In Arabidopsis thaliana, vegetative structures of the phabulosa-1d mutant are radially symmetrical, apparently as a result of adaxialization, and PHABULOSA may be one determinant of abaxial cell fate in this species (McConnell and Barton 1998). A recently described family of Arabidopsis genes, the YABBY genes, encoding putative transcription factors (Bowman and Smyth 1999;Kumaran et al. 1999;Sawa et al. 1999;Siegfried et al. 1999), participate in determination of abaxial identity in a variety of organs.