Showing papers by "Susumu Kitagawa published in 2002"

Framework Engineering by Anions and Porous Functionalities of Cu(II)/4,4‘-bpy Coordination Polymers

Abstract: A combination of framework-builder (Cu(II) ion and 4,4'-bipyridine (4,4'-bpy) ligand) and framework-regulator (AF(6) type anions; A = Si, Ge, and P) provides a series of novel porous coordination polymers. The highly porous coordination polymers ([Cu(AF(6))(4,4'-bpy)(2)].8H(2)O)(n)(A = Si (1a.8H(2)O), Ge (2a.8H(2)O)) afford robust 3-dimensional (3-D), microporous networks (3-D Regular Grid) by using AF(6)(2-) anions. The channel size of these complexes is ca. 8 x 8 A(2) along the c-axis and 6 x 2 A(2) along the a- or b-axes. When compounds 1a.8H(2)O or 2a.8H(2)O were immersed in water, a conversion of 3-D networks (1a.8H(2)O or 2a.8H(2)O) to interpenetrated networks ([Cu(4,4'-bpy)(2)(H(2)O)(2)].AF(6))(n)(A = Si (1b) and Ge (2b)) (2-D Interpenetration) took place. This 2-D interpenetrated network 1b shows unique dynamic anion-exchange properties, which accompany drastic structural conversions. When a PF(6)(-) monoanion instead of AF(6)(2)(-) dianions was used as the framework-regulator with another co-counteranion (coexistent anions), porous coordination polymers with various types of frameworks, ([Cu(2)(4,4'-bpy)(5)(H(2)O)(4)].anions.2H(2)O.4EtOH)(n)(anions = 4PF(6)(-) (3.2H(2)O.4EtOH), 2PF(6)(-) + 2ClO(4)(-) (4.2H(2)O.4EtOH)) (2-D Double-Layer), ([Cu(2)(PF(6))(NO(3))(4,4'-bpy)(4)].2PF(6).2H(2)O)(n)(5.2PF(6).2H(2)O) (3-D Undulated Grid), ([Cu(PF(6))(4,4'-bpy)(2)(MeCN)].PF(6).2MeCN)(n)(6.2MeCN) (2-D Grid), and ([Cu(4,4'-bpy)(2)(H(2)O)(2)].PF(6).BF(4))(n) (7) (2-D Grid), were obtained, where the three modes of PF(6)(-) anions are observed. 5.2PF(6).2H(2)O has rare PF(6)(-) bridges. The PF(6)(-) and NO(3)(-) monoanions alternately link to the Cu(II) centers in the undulated 2-D sheets of [Cu(4,4'-bpy)(2)](n)() to form a 3-D porous network. The free PF(6)(-) anions are included in the channels. 6.2MeCN affords both free and terminal-bridged PF(6)(-) anions. 3.2H(2)O.4EtOH, 4.2H(2)O.4EtOH, and 7 bear free PF(6)(-) anions. All of the anions in 3.2H(2)O.4EtOH and 4.2H(2)O.4EtOH are freely located in the channels constructed from a host network. Interestingly, these Cu(II) frameworks are rationally controlled by counteranions and selectively converted to other frameworks.

Formation of a one-dimensional array of oxygen in a microporous metal-organic solid

Abstract: We report the direct observation of dioxygen molecules physisorbed in the nanochannels of a microporous copper coordination polymer by the MEM (maximum entropy method)/Rietveld method, using in situ high-resolution synchrotron x-ray powder diffraction measurements. The obtained MEM electron density revealed that van der Waals dimers of physisorbed O2 locate in the middle of nanochannels and form a one-dimensional ladder structure aligned to the host channel structure. The observed O–O stretching Raman band and magnetic susceptibilities are characteristic of the confined O2 molecules in one-dimensional nanochannels of CPL-1 (coordination polymer 1 with pillared layer structure).

Novel flexible frameworks of porous cobalt(II) coordination polymers that show selective guest adsorption based on the switching of hydrogen-bond pairs of amide groups

Abstract: Four porous crystalline coordination polymers with two-dimensional frameworks of a double-edged axe-shaped motif, [[Co(NCS)(2)(3-pia)(2)] x 2 EtOH.11 H(2)O](n) (1 a), [[Co(NCS)(2)(3-pia)(2)] x 4 Me(2)CO](n) (3 a), [[Co(NCS)(2)(3-pia)(2)] x 4T HF](n) (3 b) and [[Co(NCS)(2)(3-pna)(2)](n)] (5), have been synthesized by the reaction of cobalt(II) thiocyanate with N-(3-pyridyl)isonicotinamide (3-pia) or N-(3-pyridyl)nicotinamide (3-pna). X-ray crystallographic characterization reveals that adjacent layers are stacked such that channels are created, except in 5. The channels form a hydrogen-bonded interior for guest molecules; in practice, 1 a contains ethanol and water molecules as guests in the channels with hydrogen bonds, whereas 3 b (3 a) contains tetrahydrofuran (acetone) molecules. In 1 a, the "double-edged axe-shaped" motifs in adjacent sheets are not located over the top of each other, while the motifs in 3 b stack so perfectly as to overlap each other in an edge-to-edge fashion. This subtle change in the three-dimensional framework is associated with the template effect of the guests. Compound 5 has no guest molecules and, therefore, the amide groups in one sheet are used for hydrogen-bonding links with adjacent sheets. Removal of the guest molecules from 1 a and 3 b (3 a) causes a structural conversion accompanied by a color change. Pink 1 a cannot retain its original framework and changes into a blue amorphous compound. On the other hand, the framework of pink 3 b (3 a) is transformed to a new crystalline framework of violet 4. Interestingly, 4 reverts to the original pink crystals of 3 b (3 a) when it is exposed to THF (or acetone) vapor. Spectroscopic measurements (visible, EPR, and IR) provide a clue to the crystal-to-crystal transformation; on removal of the guests, the amide groups are used to form the beta sheet-type hydrogen bonding between the sheets, and thus the framework withstands significant stress on removal of guest molecules. This mechanism is attributed to the arrangement of the adjacent sheets so suited in regularity that the beta sheet-type structure forms efficiently. The apohost 4 does not adsorb cyclopentane, showing a guest selectivity that, in addition to size, hydrogen-bonding capability is required for the guest molecules. The obtained compound is categorized as a member of a new generation of compounds tending towards functional porous coordination polymers.

Pseudo-polyrotaxane and beta-sheet layer-based three-dimensional coordination polymers constructed with silver salts and flexible pyridyl-type ligands.

Abstract: A fascinating 3D pseudo-polyrotaxane architecture with 1D polymeric [Ag(bpp)]n chains penetrating 2D (6,3) [Ag2(bpp)2(ox)]n sheets and a 3D coordination network constructed with 2D infinite [Ag(ppa...

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

Abstract: 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.

New hydrogen bond-supported 3-D molecular assembly from polyoxovanadate and tetramethylbiimidazole.

Abstract: Novel inorganic−organic hybrid compound [H2V10O28](H4tmbim)2(H2O)4 has been synthesized and characterized. All three species, decavanadate anions, biimidazolium dications, and water molecules, are hydrogen-bonded to afford a layered structure. Water molecules are intercalated between the layers to extend a three-dimensional structure.

Three-dimensional metal complex, adsorbent material and separating material

Abstract: PROBLEM TO BE SOLVED: To obtain a adsorbing material capable of selectively adsorbing a substance such as gas and a separating material having high separation performance. SOLUTION: In a porous metal complex adsorbing gases or liquids, an accumulation structure of the basic skeleton of the metal complex is changed and the size of the pores is changed by kinds of substances to be adsorbed, adsorption pressure or adsorption temperature. The adsorbing material or the separating material are each composed of the metal complex. COPYRIGHT: (C)2004,JPO

Pillared layer compounds based on metal complexes. Synthesis and properties towards porous materials

Abstract: Microporous materials have been studied extensively because of their useful properties such as gas adsorption, ion exchange, and heterogeneous catalysis. Pillared-layer structure is a representative of porous structural motifs. Not only the channel size and shape but also the chemical and physical properties could be readily designed and realized by pillar modules. A large number of pillared layer compounds, mainly in inorganic and organic-inorganic hybrid compounds, have been synthesized and characterized. On the other hand, pillared layer compounds based on coordination compounds are still sparse. We describe new types of pillared layer compounds, constructed from together with coordination compounds, focusing on structures, properties and advantages as materials, future prospects.

Synthesis and ligand-based mixed valency of cis- and trans-Cr(III)(X(4)SQ)(X(4)Cat)(L)(n) (X = Cl and Br, n = 1 or 2) complexes: effects of solvent media on intramolecular charge distribution and ligand dissociation of Cr(III)(X(4)SQ)(3).

Abstract: The treatment of Cr(III)(X(4)SQ)(3) (SQ = o-semiquinonate; X = Cl and Br) with acetonitrile affords trans-Cr(III)(X(4)SQ)(X(4)Cat)(CH(3)CN)(2) (X = Cl (1) and Br (2)) In the presence of 2,2'-bipyridine (bpy) or 3,4,7,8-tetramethyl-1,10-phenanthrene (tmphen), the reaction affords Cr(III)(X(4)SQ)(X(4)Cat)(bpy)nCH(3)CN (X = Cl, n = 1 (3); X = Br, n = 05 (4)) or Cr(III)(X(4)SQ)(X(4)Cat)(tmphen) (X = Cl (5) and Br (6)), respectively All of the complexes show a ligand-based mixed-valence (LBMV) state with SQ and Cat ligands The LBMV state was confirmed by the presence of the interligand intervalence charge-transfer band Spectroscopic studies in several solvent media demonstrate that the ligand dissociation included in the conversion of Cr(III)(X(4)SQ)(3) to 1-6 occurs only in solvents with relatively high polarity On the basis of these results, the effects of solvent media were examined and an equilibrium, Cr(III)(X(4)SQ)(3) Cr(III)(X(4)BQ)(X(4)SQ)(X(4)Cat) (BQ = o-benzoquinone), is proposed by assuming an interligand electron transfer induced by solvent polarity

Solvent-Dependent Formation of Di- and Trinuclear Rhodium and Iridium Complexes Bridged by N, N′-Donor Ligands

Abstract: Reactions of Rh and Ir hydrido complexes. [Rh(H)(2)(PPh3)(2)(solv)(EtOH)]ClO4 (solv = Me2CO, 1a; EtOH, 1b) and [Ir(H)(2)(PPh3)(2)(Me2CO)(2)]BF4 (2), with various N,N'-donor bridging ligands, such as pyrazine (pyz), 4,4'-trimethylenedipyridine (tmdp) and di(4-pyridyl) disulfide (dpds), in some solvents were examined, and their reaction products were characterized by X-ray crystal structure analysis. IR, H-1 NMR and UV-vis spectra. Rh hydrido complexes, la or 1b, formed a dinuclear Rh complex, [Rh-2(PPh3)(2) {(eta(6)-C6H5PPh2}(2)] (ClO4)(2).6CH(2)Cl(2) (3.6CH(2)Cl(2)), in dichloromethane with a reductive elimination of hydrogen. The reactions of 1a or 1b with the pyz ligand in dichloromethane and tetrahydrofuran gave triangular Rh-3 complexes, [Rh-3(PPh3)(6)(pyz)(3)](ClO4)(3).CH2Cl2 (5.CH2Cl2) and [Rh-3(PPh3)(6)(pyz)(3)](ClO4)(3).EtOH (5.EtOH), respectively, in contrast to the formation of a dinuclear Rh hydrido complex, [Rh-2(H)(4)(PPh3)(4)(Me2CO)(2)(pyz)](ClO4)(2).EtOH A-EtOH). in acetone. The reactions of la or 1b with the tmdp ligand in dichloromethane and 3-methyl-2-butanone also afforded dinuclear Rh complexes, [Rh-2(PPh3)(4)(tmdp)(2)](ClO4)(2) (6) and [Rh-2(PPh3)(4)(tmdp)(2)](ClO4)(2).4MeCOCHMe(2) (6.4MeCOCHMe(2)), respectively. On the other hand, Ir hydrido complex 2 reacted with pyz and dpds ligands in dichloromethane to afford dinuclear Ir complexes, [Ir-2(H)(4)(PPh3)(4)(Me2CO)(2)(pyz)]- (BF4)(2).3CH(2)Cl(2) (7.3CH(2)Cl(2)) and [Ir-2(H)(4)(PPh3)(4)(dpds)(2)](BF4)(2).3CH(2)Cl(2).H2O (8.3CH(2)Cl(2).H2O), respectively, without any reductive elimination of hydrogen. Based on structural studies in solution and in the solid state. it was demonstrated that various Rh and Ir complexes were selectively produced depending on the choice of solvents and N,N'-donor bridging ligands.

Preparation, crystal structures and spectroscopic properties of vanadium(III) complexes with [V–O–V]4+ cores

Abstract: Dinuclear vanadium(III) complexes, [V2(μ-O)(phen)4Cl2]Cl2·2Me2CO (1) and [V2(μ-O)(dpya)4Cl2]Cl2 (2) [phen = 1,10-phenanthroline; dpya = bis(2-pyridyl)amine], have been synthesized from the reaction of VCl3 or VCl3(THF)3 with bidentate nitrogenous ligands. The ligand substitution reaction between NaNCS and 2 yields a brown dinuclear complex, [V2(μ-O)(dpya)3(NCS)4]·2THF (3), in which each vanadium ion has a different coordination environment, and an orange mononuclear complex, [V(dpya)(NCS)4]·(Hdpya)·THF (4). Complexes 1–3 contain singly bridged [V–O–V]4+ cores. From the temperature dependence of the magnetic susceptibilities, weak magnetic interactions are observed for 1–3. UV-Vis and resonance Raman spectra of these complexes are described. The 1H NMR spectrum of 1, in which two vanadium ions are coupled antiferromagnetically, and those of its analogs have been measured and assigned.

Novel 2-dimensional coordination polymer constructed from a multi-functional metalloligand

Abstract: By employing a metalloligand {[Cu(2,4-pydca)2(H2O)]·2Et3NH} (2,4-pydca = 2,4-pyridinedicarboxylate) (1), a novel 2-D coordination polymer [ZnCu(2,4-pydca)2(H2O)2(MeOH)2]n (3) was synthesized, in which 1-D linear chains consisting of 1 and Zn(II) ions are linked by weak coordination and hydrogen bonds to form a 2-D network.

Proton spin relaxation induced by quantum tunneling in Fe8 molecular nanomagnet

Abstract: The spin-lattice relaxation rate T - 1 1 and NMR spectra of 1 H in single crystal of molecular magnets Fe8 have been measured down to 15 mK. The relaxation rate T - 1 1 shows a strong temperature dependence down to 400 mK. The relaxation is well explained in terms of the thermal transition of the iron state between the discreet energy levels of the total spin S = 10. The relaxation time T 1 becomes temperature independent below 300 mK and is longer than 100 s. In this temperature region stepwise recovery of the 1 H-NMR signal after saturation was observed depending on the return field of the sweep field. This phenomenon is attributed to the resonant quantum tunneling at the fields where levels cross and is discussed in terms of the Landau-Zener transition.

Crystal Structure and 2 D Stacking Network of [Cu(Hsal)2(py)2]n

Abstract: The title complex, [Cu(Hsal)2(py)2], was synthesized by layered solution technique and structurally characterized by single crystal X ray. The copper atom has a square pyramidal geometry and the coordination number is five. The molecular structure is linear one dimensional network. There is a stacking effect between pyridine ligands of neighbouring 1 D chains and the molecular structure is extended into two dimensional stacking network. Two salicylates in the complex have a position of crab pincers like, in which one salicylate is unidentate and another coordinates through the carboxylate group and phenyl group unidentately.

Triple Hydrogen Bond Directed Crystal Engineering of Metal Assembled Complexes: The Effect of a Novel Organic-Inorganic Module on Supramolecular Structure

Abstract: The new manganese(II) and zinc(II) triply hydrogen-bonded complexes [Hmel] 2 [M(tdpd) 2 (OH 2 ) 2 ]·2H 2 O (M = Mn 2+ ( 2 ); Hmel + = melaminium cation; H 2 tdpd = 1,4,5,6-tetrahydro-5,6-dioxo-2,3-pyrazinedicarbonitrile) have been synthesized and characterized. These complexes are isostructural as revealed by their single crystal structure analyses. Both the compounds are composed of triply hydrogen-bounded module of the AAA L DDD system. triple hydrogen bonding manganese zinc

New one-dimensional chain compounds of [M (pdz) Cl-2](n)(M=Cu(II), Fe(II), Mn(II); pdz = pyridazine and their magnetic properties

Abstract: Three novel one-dimensional coordination polymers with pyridazine (pdz),[M (pdz) Cl 2 ] n (M = Cu (II) ( 1 ), Fe (II) ( 2 ), Mn (II) ( 3 )), were synthesized and characterized. All the compounds have one-dimensional zigzag chain structures. The copper ion in compound 1 has a planer coordination sphere with two bridging pdz ligands and two C1 − anions, while the metal ions in the other compounds have a distorted octahedral environment with pdz and Cl − groups both acting as bridges. The magnetic data of these compounds show antiferromagnetic interaction between the magnetic centers within the chains.

Synthesis and Crystal Structure of One-Dimensional Copper(II) Coordination Polymer Bridged by Pyrazine Derivative

Abstract: The one-dimensional copper(II) coordination polymers [Cu(tdpd)(pda)] n ( 1 ) (H 2 tdpd=1,4,5,6-tetrahydro-5,6-dioxo-2,3-pyrazinedicarbonitrile, pda=1,2-phenylenediamine) has been synthesized and characterized. Compund 1 is a linear chain of copper(II) ions bridged by tdpd 2− dianion with terminal pda ligand. Magnetic susceptibility measurement shows antiferromagnetic couplings between the copper(II)ions.

A novel two-dimensional network constructed by bridged salicylate and pyrazine ligands with copper(II)

Abstract: The coordination polymer, [Cu2(sal)2(pyz)(H2O)2]n (H2sal=salicylic acid, pyz=pyrazine), was synthesized and structurally characterized by X-ray crystallography. The empirical formula of the polymer is CuC9NO4H8and the structural parameters are as follows: Mr=257.71, monoclinic, P21/c, Z=4, a=10.175(3) A, b=7.352(4) A, c=12.757(1) A, β=105.206(2)°, V=920.9(6) A3, Dc=1.859 g/cm3, μ(MoKα)=23.62 cm−1, F(000)=520 and the final R=0.048 for 2179 observable reflections. Each salicylate ligand connects the three copper centers to afford a novel 2-dimensional (2-D) network structure. The CuII-sal framework forms a rhombus type coordination framework. The pyz ligands fill the voids of the sheet and coordinate to the Cu site.

Synthesis and 57Fe and 151Eu Mössbauer Spectroscopic Studies of New Lanthanoid-iron Complexes

Abstract: New lanthanoid-iron 2,2′-bipyridine (bpy) and 2,2′:6′,2″-terpyridine (terpy) complexes have been investigated by a variable temperature Mossbauer spectroscopy and a single crystal structure analysis The crystal structures of Ln-bpy (Ln = La, Nd and Eu) and Eu-terpy complexes were determined as follows; {[Ln(bpy)2(H2O)4]2[(μ-NC)2Fe(CN)4]}[Fe(CN)6]·8H20 (Ln = La and Nd), {[Eu(bpy)(H2O)4][(μ-NC)2Fe(CN)4]·15bpy·4H2O]}x and {[Eu(terpy)(H2O)4][(μ-NC)2-Fe(CN)4]}x, respectively The structure of Eu-complexes consists of one-dimensional zig-zag chain polymer While La- and Nd-bpy complexes consist of discrete {[Ln(bpy)2(H2O)4]2[(μ-NC)2-Fe(CN)4]}3+ (Ln = La and Nd) cation and [Fe(CN)6]3− anion The temperature dependences of 151Eu-Mossbauer spectral area for Eu-complexes lay between those of three-dimensional polymer and monomeric molecular compounds