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Abstract: A homoleptic hexanuclear Cu cluster, [(Cu(DSB)(CBT))2(Cu2Br)2][PPh4]2 (1-PPh4 ) [DSB=2,3-disulfidobenzoate; CBT=3-carboxybenzene-1,2-bis(thiolate)] was synthesized as dark green crystals by the reaction of CuCl2 with 2,3-dimercaptobenzoic acid in acetate buffer solution. The X-ray crystal study of 1-PPh4 revealed its unique structural features: (1) one of two types of crystallographically distinct Cu centers adopted a square planer geometry and the other center had a tetrahedral geometry, and (2) intermolecular H-bonding interactions connected between carboxylic acid group of CBT and the carboxylate group of DSB led to the construction of an unprecedented topologic architecture of a zigzag patterned infinite sheet. In addition, taking into account the total charge of the molecule, which contained 2,3-disulfidobenzoate and 3-carboxybenzene-1,2-bis(thiolate), and the diamagnetic nature of 1-PPh4 , 1-PPh4 led to it is assignment as a mixed-valence Cu(I)/Cu(III) cluster. Such mixed valence states of Cu atoms were also examined by density functional theory calculation. [Copyright &y& Elsevier]

H/D isotope effects onto Br NQR frequencies of piperidinium p-bromobenzoate were studied by deuterium substitution of hydrogen atoms which form two kinds of N-H⋯O type hydrogen bonds, and the isotope shift of ca. 100 kHz were detected for a whole observed temperature range. In addition, H MAS NMR spectra measurements of piperidinium and pyrrolidinium p-bromobenzoate were carried out and little isotope changes of NMR line shape were detected. In order to reveal effects of molecular arrangements into the obtained isotope shift of NQR frequencies, single-crystal X-ray measurement of piperidinium p-bromobenzoate- d2 and density-functional-theory calculation were carried out. Our estimation showed the dihedral-angle change between piperidine and benzene ring contributes to isotope shift rather than those of N-H lengths by deuterium substitution. [ABSTRACT FROM AUTHOR]

For the purpose of investigating the correlation between host gas adsorption ability and structural flexibility, the combination of metal benzoate complexes [M2II(bza)4] (MII = Rh (a), Cu (b); bza = benzoate) and pyrazine derivatives (pyz = pyrazine (1), 2-mpyz = 2-methylpyrazine (2), 2,3-dmpyz = 2,3-dimethylpyrazine (3)) yields a series of one-dimensionally assembled complexes. The study of the adsorption properties of this series was examined for CO2, H2, N2, O2, and Ar gases at 195 K (CO2) or at 77 K (all others). The adsorption manners of these complexes are similar for each gas, while the pressure at which adsorption started or rapidly grew increased with a rise in the number of methyl groups in the case of adsorbable gases. The maximum amount of adsorption was a positive integer, e.g., 3 molecules per M2 unit for 1 and 2 and 2 molecules per M2 unit for 3 in the case of CO2 adsorption for all complexes at 0.1 MPa of adsorbable gases. Structural transformation was observed accompanying gas adsorption. This transformation was observed when the adsorption amount reached 1 molecule per M2 unit, suggesting a correlation of the adsorption amount and dynamic adsorption behavior. Single-crystal X-ray analyses of nonincluded crystals and CO2 inclusions for all hosts (1-3) revealed that large structural changes occurred through CO2 adsorption to increase the inner space for adsorption gases, depending on the substituents on the pyrazine ring. These facts were confirmed as a transition by DSC measurements using a mixed CO2/N2 gas atmosphere. Solid-state ¹H and ²H NMR studies of the crystalline sample of 1a and its partially deuterated samples of 1a′ (deuterated phenyl group) and 1a″ (deuterated pyrazine) revealed rapid 180°-flip motions of the aromatic rings of the host skeletons, which form the walls of the channels. These "rotating" motions would help the diffusion of CO2 molecules through a narrow channel at relatively low pressure. Indeed, the motions of phenyl groups and methyl-substituted pyrazine moieties of phenyl deuterated 3a were confirmed to be very slow by solid-state ¹H and ²H NMR spectra, where the amount of adsorbed gas molecules was small for 3a at 0.1 MPa of CO2. [ABSTRACT FROM AUTHOR]

We report the magnetic behaviors of O2 molecules, which aligned in the channels of four types of single-crystal adsorbents, [M2(bza)4(pyz)]n (bza = benzoate; pyz = pyrazine; M = RhII (1a) and CuII (1b)) and [M2(bza)4(2-mpyz)]n (2-mpyz = 2-methylpyrazine; M = RhII (2a) and CuII (2b)). The X-ray single-crystal structures at various temperatures from 10 to 298 K were determined for O2-included crystals of 1a and 2a. All adsorbed O2 molecules exhibited abnormal magnetic phases above 4 T in the temperature range around 55-105 K. The magnetic behaviors of adsorbed O2 molecules between four inclusions were discussed. The existence of the metastable state, which was also suggested by hysteresis on the M-H curves, was revealed by analysis of the time course of the magnetization. Considering that the abnormal magnetic behavior occurred at relatively high temperatures and a low magnetic field, it was suggested that these behaviors were induced because of the changes of magnetic interaction of included O2 aggregates involving transformation which is supported by the surrounding of the channels of the single-crystal hosts under the applied magnetic field. [ABSTRACT FROM AUTHOR]

Anomalous isotope effects were detected in the 35Cl nuclear quadrupole resonance (NQR) frequency of piperidinium p-chlrobenzoate (C5H10NH· ClC6H4COOH) by deuteration of hydrogen atoms. The atoms were determined to form two kinds of N–H···O type H-bonds in the crystal structure. Large frequency shifts of the 35Cl resonance lines reaching 288 kHz at 77 K and 278 kHz at room temperature were caused upon deuteration, in spite of the fact that the Cl atoms in the molecule do not form hydrogen bonds in the crystal. Results of single crystal X-ray diffraction measurements and density-functional-theorem calculations suggest that a dihedral-angle change of 1.8° between benzene and the piperidine ring contributes to 35Cl NQR anomalous frequency shifts. [ABSTRACT FROM AUTHOR]

Abstract: Adsorption properties of magnetic species in nano-porous crystals were studied theoretically. The crystal [Rh2bza4pyz] n , which had been reported by Mori, Takamizawa and their co-workers in detailed, was employed in this study. As adsorbed magnetic radicals, a oxygen molecule (O2; S =1) was treated. From the results by our MO calculations, weak magnetic interactions between O2 molecules in cavities existed. Two types of magnetic interactions (ferro- and antiferro-magnetic) made alignment of trimer spin structure. Our theoretical calculations analyzed not only position but also orientation of the adsorbed O2 molecules. For the position, cloud of mass densities of O2 molecules by MD simulation showed stacking styles in nano-pores statistically. Number of adsorbed gas was estimated to be 3.00 molecules/unit. For the orientation, a certain adsorbed O2 molecule was stabilized by contribution of the two next O2 molecules as well as four phenyl groups. [Copyright &y& Elsevier]

The ethanol vapor adsorption behavior and the inclusion crystal structure of a 1 D-transformable coordination polymer host were characterized. The adsorption jump was observed during phase transition or two-phase equilibrium with abnormal adsorption enthalpy caused by the nature of ‘mass induced phase transition.’ The included ethanol guests selectively form O—H···O hydrogen bonded pairs inside channels, suggesting selective construction of a specific cluster/aggregate in pores under control of thermodynamic factors and cooperative intermolecular interactions among the guest and channel surface. [ABSTRACT FROM AUTHOR]

A new series of microporous materials containing infinite chains of mononuclear metal (Cu(II), Zn(II), Ni(II))-pyridine unit bridged by dicarboxylates, copper(II) terephthalate-pyridine, [CuII(OOCC6H4COO)(C5H5N)2(H2O)] · C5H5N · H2O (1), copper(II) terephthalate-4-phenylpyridine, [CuII(OOCC6H4COO)(C11H9N)2(H2O)] · (MeOH)2 (2), zinc(II) fumarate-pyridine, [ZnII(OOCC2H2COO)(C5H5N)3] · C5H5N · (H2O)0.5 (3), zinc(II) terephthalate-pyridine, [ZnII(OOCC6H4COO)(C5H5N)2(H2O)2] · (C5H5N)2 · (H2O)2 (4), nickel(II) fumarate-pyridine, [NiII(OOCC2H2COO)(C5H5N)3] · C5H5N · (H2O)2 (5), and nickel(II) terephthalate-pyridine, [NiII(OOCC6H4COO)(C5H5N)3]6 · (C5H5N)2 · (DMF)6 · (H2O)9 (6), have been prepared. A porous structure, which is formed by stacking and self-assembly of the linear metal(II) dicarboxylates, has been determined by X-ray crystallography. When released with guest solvents, these complexes, except for 5, occlude large amounts of gases such as N2 and Ar. The maximum amount of N2 gas is 0.7–10.7 mol per mole of metal(II) salt, indicating the presence of a large number of micro- and/or mesopores. The magnetic susceptibilities of 1 and 2 obey the Curie–Weiss law over the range of 70–300 K (θ=-1.4 K and θ=+5.5 K, respectively); the obtained Weiss constants (θ) indicate the existence of small antiferromagnetic interactions (1), and ferromagnetic interactions (2). The different magnetic behaviors between 1 and 2 demonstrate that hydrogen bonding between the carboxylate groups and coordinated water molecules plays an important role in determining the bridge geometries and superexchange interaction between the Cu(II) ions through the Cu–O–C–O–H–O–Cu pathways. In contrast to those of the copper(II) complexes, the magnetic susceptibilities of 5 and 6 obey the Curie law.Novel inclusion complexes between host microporous molybdenum(II) dicarboxylates (fumarate (7), terephthalate (8), trans–trans-muconate (9), and pyridine-2,5-dicarboxylate (10)) and guest organic polyethers (poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG)) of various molecular weights have been synthesized. The rate of complex formation depends on the shapes of the micropores and polyethers. The amount of included polyethers increases with their molecular weight, and reaches up to a saturated amount, with the exception that complex 10 does not form complex with bulky PPG. The amount of absorbed argon in the microporous molybdenum(II) dicarboxylates decreases with increase in the amount of include polyethers. The 13C CP/MAS NMR measurement of complex 8 with PEG has demonstrated that PEG chains are included in the capillaries. This is an effective method for synthesizing supramolecular complexes.Three dimensional microporous polymers of Rh fumarate (Rh(f)) (11), Rh terephthalate (Rh(t)) (12), and a novel porphyrin rhodium coordination polymer, [Rh2(H2TCPP)] (H2TCPP=4,4′,4″,4‴-(21H,23H-porohine-5,10,15,20-tetrayl)tetrakis benzoic acid) complexes (13) have exhibited high catalytic activities for hydrogen exchange and hydrogenation of olefins (ethylene, propene, and butene) at 200 K. The turnover frequencies of complexes 11, 12, and 13 for hydrogenation of ethylene at 194 K are much higher than those of other published Rh-containing materials. The microwave spectroscopic analyses of the deuterium isotopic distribution of formed propene-d1 during C3H6–C3D6 reaction over complexes 11 and 12 reveal that the hydrogen exchange reactions take place only inside the nanopores of complexes 11 and 12 without complete scission of C–H bond of olefin molecule. Such a novel bimolecular pathway may play an important role for development of new heterogeneous hydrogenation catalysts. [Copyright &y& Elsevier]

Analyses the chemical reactions of the rubredoxin model complexes with reference to the molecular properties of this complex. Description of the complexes; Information on the formation of the structure of a novel chelating amido(thiolato) complex; Identification of this complex.

A novel molecular crystal membrane [Cu(ii)2(9-AC)4(pyz)]n (9-AC: 9-anthracenecarboxylate, pyz: pyrazine) shows high permselectivity for H2/CO (79.0), H2/CH4 (137), and H2/CO2 (12.1) due to the high rate of H2 permeation (3820 Barrer) while inhibiting the permeation of such a large gaseous particle even in its wider channel than the Lennard-Jones diameter of each gas. [ABSTRACT FROM AUTHOR]