A route to high surface area, porosity and inclusion of large molecules in crystals.

One of the outstanding challenges in the field of porous materials is the design and synthesis of chemical structures with exceptionally high surface areas. Such materials are of critical importance to many applications involving catalysis, separation and gas storage. The claim for the highest surface area of a disordered structure is for carbon, at 2,030 m2 g(-1) (ref. 2). Until recently, the largest surface area of an ordered structure was that of zeolite Y, recorded at 904 m2 g(-1) (ref. 3). But with the introduction of metal-organic framework materials, this has been exceeded, with values up to 3,000 m2 g(-1) (refs 4-7). Despite this, no method of determining the upper limit in surface area for a material has yet been found. Here we present a general strategy that has allowed us to realize a structure having by far the highest surface area reported to date. We report the design, synthesis and properties of crystalline Zn4O(1,3,5-benzenetribenzoate)2, a new metal-organic framework with a surface area estimated at 4,500 m2 g(-1). This framework, which we name MOF-177, combines this exceptional level of surface area with an ordered structure that has extra-large pores capable of binding polycyclic organic guest molecules--attributes not previously combined in one material.

Anisotropic shape evolution of large-size Cu nanocrystals prepared in nonionic microemulsion media.

We report the anisotropic shape evolution of colloidal copper nanocrystals (Cu NCs) in nonionic microemulsion media by adopting tetraethylammonium hydroxide as a reactant and capping agent in water phase. Relatively large-size Cu NCs were synthesized to confine the growth of Cu NCs below 100 nm. TEM images showed the triangular and hexagonal morphologies of Cu NCs ranging over 55-70 nm after 28 h, while they showed the spherical NCs dominantly under higher concentration of a reducing agent. The surface plasmon resonance (SPR) absorption band of anisotropic Cu NCs was centered at 571 nm with signal enhancement over time. The formation kinetics revealed that the gradual conversion of the Cu seeds into larger NCs during 28 h at room temperature. The NCs were characterized to be Cu rather than CuO or Cu2O by electron diffraction patterns, exhibiting relevant d-spacing figures consistent with the bulk Cu crystal.

Exceptional chemical and thermal stability of zeolitic imidazolate frameworks.

Twelve zeolitic imidazolate frameworks (ZIFs; termed ZIF-1 to -12) have been synthesized as crystals by copolymerization of either Zn(II) (ZIF-1 to -4, -6 to -8, and -10 to -11) or Co(II) (ZIF-9 and -12) with imidazolate-type links. The ZIF crystal structures are based on the nets of seven distinct aluminosilicate zeolites: tetrahedral Si(Al) and the bridging O are replaced with transition metal ion and imidazolate link, respectively. In addition, one example of mixed-coordination imidazolate of Zn(II) and In(III) (ZIF-5) based on the garnet net is reported. Study of the gas adsorption and thermal and chemical stability of two prototypical members, ZIF-8 and -11, demonstrated their permanent porosity (Langmuir surface area = 1,810 m(2)/g), high thermal stability (up to 550 degrees C), and remarkable chemical resistance to boiling alkaline water and organic solvents.

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. In particular, highly porous frameworks held together by strong metal-oxygen-carbon bonds and with exceptionally large surface area and capacity for gas storage have been prepared and their pore metrics systematically varied and functionalized.