There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

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.

The Chemistry and Applications of Metal-Organic Frameworks

J. Appl. Cryst.の発刊に際して

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.

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Reticular synthesis and the design of new materials

Biofuels have attracted attention in this decade as an alternative energy resource to limited fossil fuels. The world production of bioethanol considerably increased from 17 billion liters in 2000 to more than 46 billion liters in 2007. [ 1 ] Most bioethanol is currently produced from food crops, such as corn and sugarcane, as biomass resources because the food crops derive water-soluble starch that can be easily converted to bioethanol by yeast bacteria or acid catalysts. However, this ethanol production process consumes huge amounts of food crops and competes with the supply of food. To overcome this problem, starch-derived ethanol is anticipated to be replaced by cellulose-derived ethanol because the cellulose can be conveniently obtained from wooden or grain plant fi bers that do not compete with the food supply. Recently, several solvent media and catalysts for the hydrolysis of cellulose have been investigated, including supercritical water, ionic liquids, mesoporous carbon functionalized with ruthenium metal or SO 3 H groups, and sulfonated ion exchange resins. [ 2–9 ] Nevertheless, further development of more effective and “green” materials for hydrolysis of cellulose is required. Porous coordination polymers (PCPs) or metal-organic frameworks (MOFs), composed of metal ions and various organic ligands, have been extensively studied as a new class of porous solids. One of the advantages of PCPs is their highly designable framework, which provides a large variety of pore surfaces and pore structures. [ 10–16 ] Here we show the synthesis of a new PCP (compound 1 ) that has the sulfonic acid groups as a very strong acid on its pore surface and demonstrate its catalytic performance for cellulose hydrolysis. It is essential to decorate the pore surface with a Brønsted acid for the fabrication of a solid acid catalyst. Whereas many

Cellulose Hydrolysis by a New Porous Coordination Polymer Decorated with Sulfonic Acid Functional Groups

Solid Solutions of Soft Porous Coordination Polymers: Fine-Tuning of Gas Adsorption Properties

Flexible porous coordination polymers containing amide groups as a function origin have been synthesized and categorized as “Coordination Polymer with Amide Groups”. Bispyridyl ligands with a spacer of amide group afford two-dimensional (2-D) motifs with a deformed square grid, resulting in three-dimensional (3-D) frameworks of [Co(NO3)2(3-pna)2]n (1), [Co(Br)2(3-pna)2]n (2), and {[Co(NCS)2(4-peia)2]·4Me2CO}n (3 ⊃ 4Me2CO) (3-pna = N-3-pyridylnicotinamide, 4-peia = N-(2-pyridin-4-yl-ethyl)-isonicotinamide), where the 2-D motifs are bound by complementary hydrogen bond between the amide groups. In the case of the 3 ⊃ 4Me2CO, the amide groups form a contrivance for a dynamic porous framework because of their relevant position and orientation in the mutual nearest neighboring motifs. Consequently, 3 ⊃ 4Me2CO shows amorphous (nonporous)-to-crystal (porous) structural rearrangement in the Me2CO adsorption and desorption process, where the framework of the 2-D motif is maintained. The adsorption isotherm has thr...

A Contrivance for a Dynamic Porous Framework: Cooperative Guest Adsorption Based on Square Grids Connected by Amide−Amide Hydrogen Bonds

A new aluminum naphthalenedicarboxylate Al(OH)(1,4-NDC)·2H2O compound has been synthesized. The crystal structure exhibits a three-dimensional framework composed of infinite chains of corner-sharing octahedral Al(OH)2O4 with 1,4-naphthanedicarboxylate ligands forming two types of channels with squared-shape cross-section. The large channels present a cross-section of 7.7 × 7.7 A2, while the small channels are about 3.0 × 3.0 A2. When water molecules are removed, no structural transformation occurs, generating a robust structure with permanent porosity and remarkable thermal stability. 2D 1H−13C heteronuclear correlation NMR measurements, together with the application of Lee-Goldburg homonuclear decoupling, were applied, for the first time, to porous coordination polymers revealing the spatial relationships between the 1H and 13C spin-active nuclei of the framework. To demonstrate the open pore structure and the easy accessibility of the nanochannels to the gas phase, highly sensitive hyperpolarized (HP) x...

Nanochannels of two distinct cross-sections in a porous Al-based coordination polymer

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...

Susumu Kitagawa

Papers

Cellulose Hydrolysis by a New Porous Coordination Polymer Decorated with Sulfonic Acid Functional Groups

Solid Solutions of Soft Porous Coordination Polymers: Fine-Tuning of Gas Adsorption Properties

A Contrivance for a Dynamic Porous Framework: Cooperative Guest Adsorption Based on Square Grids Connected by Amide−Amide Hydrogen Bonds

Nanochannels of two distinct cross-sections in a porous Al-based coordination polymer

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