Tomohiko Ishii

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)

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.

Cocrystallites consisting of metal macrocycles with fullerenes

Abstract The cocrystallites that contain C 60 , C 70 and endohedral metallofullerenes with metal complexes of macrocycles are reviewed. Metal complexes of porphyrin cocrystallites with fullerenes form solids with remarkably close contact between the curved π surface of a fullerene and the planar π surface of a porphyrin, without the need for matching convex with concave surfaces. The structures of metal octaethylporphyrins (oeps) in C 60 ·Pd(II)(oep)·1.5C 6 H 6 , C 60 ·Cu(II)(oep)·2C 6 H 6 , C 60 ·Ag(II)(oep)·2C 6 H 6 and C 60 ·2Ni(II)(oep)·2C 6 H 5 Cl reveal the remarkable anti -formed oep configurations, with the four ethyl groups of the metal oep portions lying on both the same and the opposite sides of the porphyrin plane toward the C 60 . On the other hand, syn -formed metal oeps are observed in the many cases of metal oep compounds, suggesting that there is a face-to-face interaction between two adjacent oep planes. A new cocrystallite which exhibits a strong intermolecular interaction between fullerene C 60 and the Co(tbp) is also reviewed, where tbp denotes a dianion of tetra(bis- tert -butylphenyl)porphyrin. The intermolecular interactions of the anti - and syn -formed metal oeps in the cocrystallites containing fullerenes are also described by DV-Xα molecular orbital calculation.

Rationale Synthese stabiler, kanalartiger Käfige mit Methan‐adsorbierenden Eigenschaften: [{Cu2(pzdc)2(L)}n] (pzdc=Pyrazin‐2,3‐dicarboxylat; L=Säulenligand)

Stabile Kanale mit einstellbaren Eigenschaften werden in [{Cu2(pzdc)2(L)}n]-Koordinationsnetzen des Saulen-Schicht-Typs gebildet (pzdc=Pyrazin-2,3-dicarboxylat; L=Pyrazin, 4,4′-Bipyridin oder N-(4-Pyridyl)isonicotinamid). Durch Wahl der Saulenliganden lassen sich Grose, Form und chemische Umgebung der Kanale systematisch einstellen; die Porositat bleibt auch ohne Gastmolekule erhalten. Die Verbindungen konnen Methan adsorbieren, und die adsorbierte Gasmenge ist durch die Art des Saulenliganden kontrollierbar.

A New Anion‐Trapping Radical Host, [(Cu‐dppe)3{hat‐(CN)6}]2+

Anions PF6- and CF3 SO3- are trapped by the new radical host [(Cu-dppe)3 {hat-(CN)6 }]2+ , which was synthesized in a one-pot reaction from a copper(I) source, hat-(CN)6 , and dppe in acetone. The trapped salts have been characterized both in solution and in the solid state (see picture: A- : PF6- , CF3 SO3- ). hat-(CN)6 =hexaazatriphenylene hexacarbonitrile; dppe=1,2-bis(diphenylphosphanyl)ethane.

Haldane gap systems

Abstract Haldane gap compounds with S =1 formulated as [Ni(AA) 2 X]Y ((AA) 2 =(diamines) 2 , linear-tetramines, N 4 -macrocycles; X=NO 2 and N 3 ; Y=ClO 4 , BF 4 and PF 6 ) and (CH 3 ) 4 N[Ni(NO 2 ) 3 ], and with S =2 formulated as [Mn(AA) 2 Cl 3 ] (AA=bipy and phen) are described. They have one-dimensional structures with bridging ligands. The Haldane conjecture was proven by magnetic susceptibility and high-field magnetization measurements. The magnitudes of the Haldane gap with S =1 can be controlled by combination of the bridging ligands, in-plane ligands, and counteranions as follows: X, N 3 >NO 2 ; AA, en≧tn>linear-tetramines>dmpn>Me 6 [14]aneN 4 ≧[15]aneN 4 ; Y, ClO 4 >PF 6 . In spite of a similar structure to Haldane gap compounds, the [Ni([15]aneN 4 )N 3 ]PF 6 and [Ni(en) 2 (NO 2 )]BF 4 species show spin-glass behavior, which is very novel in one-dimensional spin systems. The [Mn(bipy)Cl 3 ] is regarded as the first example of the Haldane gap system with S =2.

The rational syntheses of manganese-chloranilate compounds: crystal structures and magnetic properties

[Mn(CA)(terpy)] n ( 1 ) and {[Mn(CA)(bipym) 0.5 (H 2 O)](H 2 O)(C 2 H 5 OH)} n ( 2 ) (H 2 CA=chloranilic acid, terpy=2,2′:6′,2″-terpyridine and bipym=2,2′-bipyrimidine) have been synthesized and their crystal structures determined by a single-crystal X-ray diffraction. Compound 1 is made up of infinite chains of chloranilate-bridged manganese(II), affording a zig–zag pattern, with terpyridine ligands stacking between the chains. Compound 2 has a novel honeycomb layered structure, where each hexagon consists of six Mn(II) ions, four CA 2− and two bipym ligands. Mn(II) ions in both compounds are unusually hepta-coordinated. Magnetic susceptibility measurements of both compounds show weak antiferromagnetic coupling between the nearest Mn(II) ions.

Syntheses and electronic structures of macrocyclic metal complexes with fullerene

Abstract New cocrystallines are reported that contain C 60 with anti-formed macrocyclic metal complexes of octaethylporphyrin (OEP). From the results of the electronic structure obtained using a DV-Xα molecular orbital calculation, the configuration of the OEP in a cocrystalline of C 60 with Ag(II)(OEP) or Ni(II)(OEP) is predicted to be the anti-formed structure. It is shown that the anti-formed configuration of the OEPs can be confirmed in Ag(II)(OEP)·C 60 ·2C 6 H 6 and 2Ni(II)(OEP)·C 60 ·2C 6 H 5 Cl according to a structural prediction we have made by means of electronic structure calculations using the DV-Xα method. It is also revealed that the C 60 is located at the closest approach to the centered atom involving the 5:6 carbon ring junction in these cocrystallines. Using the DV-Xα method, it is predicted that new types of π–d material can be produced. The material should have high conductivity and a significant magnetic moment via the π–d interaction in the charge transfer salt of [Cr(III)(Por)] + [C 60 ] − .

Temperature-Independent Hole Mobility of a Smectic Liquid-Crystalline Semiconductor based on Band-Like Conduction

A liquid-crystalline (LC) phenylterthiophene derivative, which exhibited an ordered smectic phase at room temperature, was purified by vacuum sublimation under a flow of nitrogen. During the sublimation process, thin plates with sizes of 1 mm grew on the surface of the vacuum tube. The crystals exhibited the same X-ray diffraction patterns as the ordered smectic phase of the LC state that was formed through a conventional recrystallization process by using organic solvents. Because of the removal of chemical impurities, the hole mobility in the ordered smectic phase of the vacuum-grown thin plates increased to 1.2×10(-1) cm(2) V(-1) s(-1) at room temperature, whereas that of the LC precipitates was 7×10(-2) cm(2) V(-1) s(-1). The hole mobility in the ordered smectic phase of the vacuum-sublimated sample was temperature-independent between 400 and 220 K. The electric-field dependence of the hole mobility was also very small within this temperature range. The temperature dependence of hole mobility was well-described by the Hoesterey-Letson model. The hole-transport characteristics indicate that band-like conduction affected by the localized states, rather than a charge-carrier-hopping mechanism, is a valid mechanism for hole transport in an ordered smectic phase.

Out-of-plane dimers of Mn(III) quadridentate Schiff-base complexes with saltmen2− and naphtmen2− ligands: structure analysis and ferromagnetic exchange

Six Mn(III) quadridentate Schiff base compounds with N,N′-(1,1,2,2-tetramethylethylene)bis(salicylideneiminato) dianion (saltmen2−) and N,N′-(1,1,2,2-tetramethylethylene)bis(naphthylideneiminato) dianion (naphtmen2−) have been prepared and structurally characterized: [Mn(saltmen)(H2O)]ClO4 (1), [Mn(naphtmen)(H2O)]ClO4 (2), [Mn(saltmen)(NCS)] (3), [Mn(naphtmen)(NCS)] (4), [Mn(saltmen)(Cl)] (5) and [Mn(naphtmen)(Cl)] (6). Among them, 1 and 2 form phenolate-bridged out-of-plane dimers with Mn–Ophenolate bond distances of 2.434(2) and 2.662(3) A, respectively. X-Ray diffraction analysis shows that compounds 3, 4 and 6 can also be considered as out-of-plane dimers in spite of long Mn–Ophenolate interacting distances (3.441(2) A for 3, 3.758(3) A for 4 and 3.505(5) A for 6). In contrast with the above compounds, 5 is a discrete Mn(III) mononuclear complex with a square-pyramidal geometry. In the dimer series (compounds 1–4 and 6), the out-of-plane intermolecular distance varies dramatically according to equatorial ligands, saltmen2− or naphtmen2−, and axial ligands, H2O, NCS− and Cl−. The relation between substitution of the ligands and structural parameters of the dimeric molecules are discussed. Magnetic susceptibility studies reveal interesting intra-dimer ferromagnetic interactions between Mn(III) ions. Our work reports on these new S = 4 building blocks that open new possibilities in the design of magnetic molecule-based materials.

Catalytic reaction mechanism of Pseudomonas stutzeri l-rhamnose isomerase deduced from X-ray structures

l‐Rhamnose isomerase (l‐RhI) catalyzes the reversible isomerization of l‐rhamnose to l‐rhamnulose. Pseudomonas stutzeril‐RhI, with a broad substrate specificity, can catalyze not only the isomerization of l‐rhamnose, but also that between d‐allose and d‐psicose. For the aldose–ketose isomerization by l‐RhI, a metal‐mediated hydride‐shift mechanism has been proposed, but the catalytic mechanism is still not entirely understood. To elucidate the entire reaction mechanism, the X‐ray structures of P. stutzeril‐RhI in an Mn2+‐bound form, and of two inactive mutant forms of P. stutzeril‐RhI (S329K and D327N) in a complex with substrate/product, were determined. The structure of the Mn2+‐bound enzyme indicated that the catalytic site interconverts between two forms with the displacement of the metal ion to recognize both pyranose and furanose ring substrates. Solving the structures of S329K–substrates allowed us to examine the metal‐mediated hydride‐shift mechanism of l‐RhI in detail. The structural analysis of D327N–substrates and additional modeling revealed Asp327 to be responsible for the ring opening of furanose, and a water molecule coordinating with the metal ion to be involved in the ring opening of pyranose.