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

The complex (di-2-pyridyl sulfide-N,N')dichlorooxovanadium(IV), [VOCl 2 (C 10 H 8 N 2 S)], was prepared by the reaction of VCl 3 and sodium 2-mercaptopyridine N-oxide in ethanol solution under an atmosphere of argon. The N atoms of the dipyridyl sulfide ligand and the two chloride ligands coordinate to the oxovanadium(IV) ion, to give a complex with square-pyramidal geometry. The dipyridyl sulfide ligand forms a folded six-membered chelate ring with a larger N−V−N bite angle than that formed by 2,2'-bipyridyl

An Oxovanadium(IV) Complex Chelated by Dipyridyl Sulfide

New lanthanoid-iron complexes having phenanthlorine as the chelating ligand were synthesized and characterized by151Eu- and57Fe-Mossbauer spectroscopy. The temperature dependence of the area intensity of Mossbauer lines of europium complexes (single crystals) has been correlated to the state of molecular association in the solid state. The crystal structure of europium complex, {[Eu(phen)2(H2O)2][(μ-NC)2 Fe(CN)4]·2phen]}x was determined by X-ray crystal analysis. This complex consists of one-dimensional zig-zag chain structure.

Synthesis and151Eu- and57Fe-Mössbauer spectroscopic studies of new europium-iron complexes

The combination of salicylic acid and 4-aminopyridine leads to a 3D hydrogen bonding network while the replacement of 4-aminopyridine with 4,4′-bipyridine yields the same topological net with big channels via coordination.

Crystal Engineering of 3D Porous Coordination Polymers through Hydrogen Bonding to Coordination from 1D Helical Chains

Chemical oxidation of [Ru2(6+)(3,6-DTBCat)4]2- affords [n-Bu4N][Ru2(3,6-DTBDiox)4].acetone (2.acetone). The oxidized species was characterized by X-ray crystallographic analysis and EPR, and the delocalization of the unpaired electron over the entire molecule was indicated. This example showed that the utilization of redox-active ligands into a Ru2 complex expanded the degree of freedom in the electronic structure. DFT calculations support this view, and the spin population was estimated to be approximately 18% and 82% for the Ru2 core and the four dioxolene ligands, respectively.

Structural and spectroscopic characterization of a diruthenium o-dioxolene complex possessing a singly occupied molecular orbital delocalized over the entire molecule, [Ru2(3,6-DTBDiox)4]-.

Susumu Kitagawa

Papers

An Oxovanadium(IV) Complex Chelated by Dipyridyl Sulfide

Synthesis and151Eu- and57Fe-Mössbauer spectroscopic studies of new europium-iron complexes

Crystal Engineering of 3D Porous Coordination Polymers through Hydrogen Bonding to Coordination from 1D Helical Chains

Structural and spectroscopic characterization of a diruthenium o-dioxolene complex possessing a singly occupied molecular orbital delocalized over the entire molecule, [Ru2(3,6-DTBDiox)4]-.

Dynamic porous frameworks of coordination polymers controlled by anions