Super flexibility of a 2D Cu-based porous coordination framework on gas adsorption in comparison with a 3D framework of identical composition: framework dimensionality-dependent gas adsorptivities

Selective synthetic routes to coordination polymers [Cu(bpy)(2)(OTf)(2)](n) (bpy = 4,4'-bipyridine, OTf = trifluoromethanesulfonate) with 2- and 3-dimensionalities of the frameworks were established by properly choosing each different solvent-solution system. They show a quite similar local coordination environment around the Cu(II) centers, but these assemble in a different way leading to the 2D and 3D building-up structures. Although the two kinds of porous coordination polymers (PCPs) both have flexible frameworks, the 2D shows more marked flexibility than the 3D, giving rise to different flexibility-associated gas adsorption behaviors. All adsorption isotherms for N(2), CO(2), and Ar on the 3D PCP are of type I, whereas the 2D PCP has stepwise gas adsorption isotherms, also for CH(4) and water, in addition to these gases. The 3D structure, having hydrophilic and hydrophobic pores, shows the size-selective and quadrupole-surface electrical field interaction dependent adsorption. Remarkably, the 2D structure can accommodate greater amounts of gas molecules than that corresponding to the inherent crystallographic void volume through framework structural changes. In alcohol adsorption isotherms, however, the 2D PCP changes its framework structure through the guest accommodation, leading to no stepwise adsorption isotherms. The structural diversity of the 2D PCP stems from the breathing phenomenon and expansion/shrinkage modulation.     

Isokinetic trunk and knee muscle strengths and gait performance in walking patients with T-cell lymphotropic virus type 1-associated myelopathy/ tropical spastic paraparesis (HAM/TSP)

The aim of this study was to investigate the isokinetic trunk and knee muscle strengths, and examine the clinical relevance of dynamic muscle strengths and gait performance in walking patients with human T-cell lymphotropic virus type 1-associated myelopathy/ tropical spastic paraparesis (HAM/TSP). Thirteen patients with HAM/TSP (8 females and 5 males, aged 38–76) and 13 sex- and age-matched healthy control subjects participated in the study. We assessed gait speed, stride length, cadence; and maximal isokinetic torque of trunk and knee extensors and flexors at 30°/s, 60°/s and 90°/s using a Biodex System 3 dynamometer. Furthermore, we calculated the isokinetic trunk extensor/flexor (E/F) and hamstrings/quadriceps (H/Q) strength ratios (parameter of the muscle strength balance about the trunk and knee joint). Compared with the age-matched controls, the patients with HAM/TSP had significantly reduced gait speed, stride length and cadence (P < 0.05). Peak torque values related to body weight (PTBW) were significantly reduced, especially for the knee flexors (P < 0.05). For the knee extensors, the PTBW values were significantly reduced at an increased angular velocity (P < 0.05). The PTBW of knee flexors was positively correlated with gait speed and cadence in the patients with HAM/TSP. The H/Q ratio but not E/F ratio was significantly decreased compared with the control. Our results indicated that the isokinetic trunk and knee muscle performance had reduced from the ambulatory stage, and suggested the deterioration in knee muscle performance to be associated with gait disturbance in walking HAM/TSP patients.     

Structural and dehydriding properties of Ca(BH<Subscript>4</Subscript>)<Subscript>2</Subscript>

We have investigated the structural and dehydriding properties of Ca(BH₄)₂. It was found that Ca(BH₄)₂ undergoes a structural phase transformation from an orthorhombic low-temperature (LT) modification into a tetragonal high-temperature (HT) modification between 433 K and 523 K. The amount of hydrogen desorbed from Ca(BH₄)₂ during the pressure–composition (p–c) isotherm measurement was 5.9 mass%. This hydrogen desorption is caused by the partial dehydrogenation of Ca(BH₄)₂ accompanied by the formation of CaH₂ and orthorhombic intermediate phases.     

Isomorphisms of Galois groups of number fields with restricted ramification

Let K be a number field and S a set of primes of K. We write $K_S/K$ for the maximal extension of K unramified outside S and $G_{K,S}$ for its Galois group. In this paper, we answer the following question under some assumptions: “For $i=1,2$, let $K_i$ be a number field, $S_i$ a (sufficiently large) set of primes of $K_i$ and $\sigma :G_{K_1,S_1}\stackrel{\sim }{\to }{G}_{K_2,S_2}$ an isomorphism. Is σ induced by a unique isomorphism between $K_{1,S_1}/K_1$ and $K_{2,S_2}/K_2$?” Here, the main assumption is about the Dirichlet density of $S_i$.     

Structural-transformation-induced Drastic Luminescence Changes in an Organic-Inorganic Hybrid [ReN(CN)4]2− Salt Triggered by Chemical Stimuli

We synthesized a (1-propylpyridinium)₂[ReN(CN)₄]-type organic–inorganic hybrid exhibiting water-vapor-induced drastic structural changes of the [ReN(CN)₄]²⁻ assemblies. Specifically, upon exposure to water vapor, dehydrated nitrido-bridged chains were converted to hydrated cyanido-bridged tetranuclear clusters via rearrangements of large molecular building units in the crystals. These switchable assembly forms display substantially different photo-physical properties, although in both cases the emission is caused by a metal-centered d–d transition. The nitrido-bridged chain exhibited a near-infrared (749 nm) emission, which blue-shifted as the temperature increased, while a visible (561 nm) emission and its red shift was demonstrated by the cyanido-bridged cluster.     

Synthesis of β‐monosubstituted α,β‐unsaturated amides with Z‐selectivity using diphenylphosphonoacetamides

The utility of diphenylphosphonoacetamides [(PhO)₂P(O)CH₂CONRR′] as Horner–Wadsworth–Emmons reagents was examined with five different patterns of substitution upon the amide nitrogen atom ( 2a : R, R′ = CH₂Ph; 2b : R = CH₂Ph, R′ = H; 2c : R = Me, R′ = OMe; 2d : R, R′ = Ph; 2e : R, R′ = (CH₂)₄). The reaction of 2a was found to be Z‐selective for aromatic aldehydes with selectivities up to 95:5. Reagent 2b led to reasonable selectivity for both benzaldehyde (85:15) and 3‐phenylpropionaldehyde (87:13), while 2c was somewhat effective for only the latter alkyl aldehyde (83:17). Compounds 2d and 2e exhibited slightly lower selectivities compared with 2a . © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:515–523, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20054