Kenji Seki

Bio: Kenji Seki is an academic researcher from Southern California Gas Company. The author has contributed to research in topics: Methane & Adsorption. The author has an hindex of 13, co-authored 43 publications receiving 4031 citations.

Rational Synthesis of Stable Channel‐Like Cavities with Methane Gas Adsorption Properties: [{Cu2(pzdc)2(L)}n] (pzdc=pyrazine‐2,3‐dicarboxylate; L=a Pillar Ligand)

Abstract: Stable tunable channels are formed by pillared-layer-type coordination networks [{Cu2(pzdc)2(L)}n] (pzdc = pyrazine-2,3-dicarboxylate; L = pyrazine, 4,4′-bipyridine, N-(4-pyridyl)isonicotinamide). Not only their channel sizes, shapes, and chemical environments are systematically built up by tuning the pillar ligands, but also the porosity is maintained in the absence of the included guest molecules. These compounds can adsorb methane, and the amount of gas adsorption is controllable by the type of pillar ligands.

Microporous materials constructed from the interpenetrated coordination networks. Structures and methane adsorption properties

Abstract: Five new coordination compounds with 4,4‘-azopyridine (azpy), [Mn(azpy)(NO3)2(H2O)2]·2EtOH (1·2EtOH), [Co2(azpy)3(NO3)4]·Me2CO·3H2O (2·Me2CO·3H2O), [Co(azpy)2(NCS)2]·0.5EtOH (3·0.5EtOH), [Cd(azpy)2(NO3)2]·(azpy) (4·azpy), and [Cd2(azpy)3(NO3)4]·2Me2CO (5·2Me2CO), have been synthesized and structurally characterized. The reaction of Mn(NO3)2·6H2O with azpy in ethanol/acetone affords 1·2EtOH, whose network consists of one-dimensional chains of [Mn(azpy)(H2O)2]n. The chains are associated by hydrogen bonding to provide a logcabin-type three-dimensional structure, which creates about 8 × 8 A of channels, filled with ethanol molecules. The treatment of Co(NO3)2·6H2O and Co(NCS)2·4H2O with azpy produces 2·Me2CO·3H2O and 3·0.5EtOH, respectively, which have a brick-wall and a rhombus-type two-dimensional networks. The reaction of Cd(NO3)2·4H2O with azpy affords 4·azpy from the ethanol/H2O media, while the reaction in the ethanol/acetone media provides 5·2Me2CO. 4·azpy and 5·2Me2CO form a square-grid- and a herrin...

The Chemistry and Applications of Metal-Organic Frameworks

Abstract: Crystalline metal-organic frameworks (MOFs) are formed by reticular synthesis, which creates strong bonds between inorganic and organic units. Careful selection of MOF constituents can yield crystals of ultrahigh porosity and high thermal and chemical stability. These characteristics allow the interior of MOFs to be chemically altered for use in gas separation, gas storage, and catalysis, among other applications. The precision commonly exercised in their chemical modification and the ability to expand their metrics without changing the underlying topology have not been achieved with other solids. MOFs whose chemical composition and shape of building units can be multiply varied within a particular structure already exist and may lead to materials that offer a synergistic combination of properties.

Reticular synthesis and the design of new materials

Abstract: 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.

Selective gas adsorption and separation in metal–organic frameworks

Abstract: Adsorptive separation is very important in industry. Generally, the process uses porous solid materials such as zeolites, activated carbons, or silica gels as adsorbents. With an ever increasing need for a more efficient, energy-saving, and environmentally benign procedure for gas separation, adsorbents with tailored structures and tunable surface properties must be found. Metal–organic frameworks (MOFs), constructed by metal-containing nodes connected by organic bridges, are such a new type of porous materials. They are promising candidates as adsorbents for gas separations due to their large surface areas, adjustable pore sizes and controllable properties, as well as acceptable thermal stability. This critical review starts with a brief introduction to gas separation and purification based on selective adsorption, followed by a review of gas selective adsorption in rigid and flexible MOFs. Based on possible mechanisms, selective adsorptions observed in MOFs are classified, and primary relationships between adsorption properties and framework features are analyzed. As a specific example of tailor-made MOFs, mesh-adjustable molecular sieves are emphasized and the underlying working mechanism elucidated. In addition to the experimental aspect, theoretical investigations from adsorption equilibrium to diffusion dynamics via molecular simulations are also briefly reviewed. Furthermore, gas separations in MOFs, including the molecular sieving effect, kinetic separation, the quantum sieving effect for H2/D2 separation, and MOF-based membranes are also summarized (227 references).

Systematic Design of Pore Size and Functionality in Isoreticular MOFs and Their Application in Methane Storage

Abstract: A strategy based on reticulating metal ions and organic carboxylate links into extended networks has been advanced to a point that allowed the design of porous structures in which pore size and functionality could be varied systematically. Metal-organic framework (MOF-5), a prototype of a new class of porous materials and one that is constructed from octahedral Zn-O-C clusters and benzene links, was used to demonstrate that its three-dimensional porous system can be functionalized with the organic groups –Br, –NH2, –OC3H7, –OC5H11, –C2H4, and –C4H4 and that its pore size can be expanded with the long molecular struts biphenyl, tetrahydropyrene, pyrene, and terphenyl. We synthesized an isoreticular series (one that has the same framework topology) of 16 highly crystalline materials whose open space represented up to 91.1% of the crystal volume, as well as homogeneous periodic pores that can be incrementally varied from 3.8 to 28.8 angstroms. One member of this series exhibited a high capacity for methane storage (240 cubic centimeters at standard temperature and pressure per gram at 36 atmospheres and ambient temperature), and others the lowest densities (0.41 to 0.21 gram per cubic centimeter) for a crystalline material at room temperature.