Molecules exhibiting bistability have been proposed as elementary binary units (bits) for information storage, potentially enabling fast and efficient computing. In particular, transition metal ...complexes can display magnetic bistability via either spin-crossover or single-molecule magnet behavior. We now show that the octahedral iron(II) complexes in the molecular salt Fe(1-propyltetrazole)6(BF4)2, when placed in its high-symmetry form, can combine both types of behavior. Light irradiation under an applied magnetic field enables fully reversible switching between an S = 0 state and an S = 2 state with either up (M S = +2) or down (M S = −2) polarities. The resulting tristability suggests the possibility of using molecules for ternary information storage in direct analogy to current binary systems that employ magnetic switching and the magneto-optical Kerr effect as write and read mechanisms.
The metal–organic frameworks M2(m-dobdc) (M = Mn, Fe, Co, Ni; m-dobdc4– = 4,6-dioxido-1,3-benzenedicarboxylate) were evaluated as adsorbents for separating olefins from paraffins. Using ...single-component and multicomponent equilibrium gas adsorption measurements, we show that the coordinatively unsaturated M2+ sites in these materials lead to superior performance for the physisorptive separation of ethylene from ethane and propylene from propane relative to any known adsorbent, including para-functionalized structural isomers of the type M2(p-dobdc) (p-dobdc4– = 2,5-dioxido-1,4-benzenedicarboxylate). Notably, the M2(m-dobdc) frameworks all exhibit an increased affinity for olefins over paraffins relative to their corresponding structural isomers, with the Fe, Co, and Ni variants showing more than double the selectivity. Among these frameworks, Fe2(m-dobdc) displays the highest ethylene/ethane (>25) and propylene/propane (>55) selectivity under relevant conditions, together with olefin capacities exceeding 7 mmol/g. Differential enthalpy calculations in conjunction with structural characterization of ethylene binding in Co2(m-dobdc) and Co2(p-dobdc) via in situ single-crystal X-ray diffraction reveal that the vast improvement in selectivity arises from enhanced metal–olefin interactions induced by increased charge density at the metal site. Moderate olefin binding enthalpies, below 55 and 70 kJ/mol for ethylene and propylene, respectively, indicate that these adsorbents maintain sufficient reversibility under mild regeneration conditions. Additionally, transient adsorption experiments show fast kinetics, with more than 90% of ethylene adsorption occurring within 30 s after dosing. Breakthrough measurements further indicate that Co2(m-dobdc) can produce high purity olefins without a temperature swing, an important test of process applicability. The excellent olefin/paraffin selectivity, high olefin capacity, rapid adsorption kinetics, and low raw materials cost make the M2(m-dobdc) frameworks the materials of choice for adsorptive olefin/paraffin separations.
Chlorine radicals readily activate C–H bonds, but the high reactivity of these intermediates precludes their use in regioselective C–H functionalization reactions. We demonstrate that the secondary ...coordination sphere of a metal complex can confine photoeliminated chlorine radicals and afford steric control over their reactivity. Specifically, a series of iron(III) chloride pyridinediimine complexes exhibit activity for photochemical C(sp3)–H chlorination and bromination with selectivity for primary and secondary C–H bonds, overriding thermodynamic preference for weaker tertiary C–H bonds. Transient absorption spectroscopy reveals that Cl· remains confined through formation of a Cl·|arene complex with aromatic groups on the pyridinediimine ligand. Furthermore, photocrystallography confirms that this selectivity arises from the generation of Cl· within the steric environment defined by the iron secondary coordination sphere.
Rosa AR, González‐Ortega I, González‐Pinto A, Echeburúa E, Comes M, Martínez‐Àran A, Ugarte A, Fernández M, Vieta E. One‐year psychosocial functioning in patients in the early vs. late stage of ...bipolar disorder.
Objective: The aim of this 1‐year follow‐up study was to compare functional outcome as well as clinical differences between patients with first‐ and multiple‐episode bipolar disorder.
Method: Bipolar disorder patients with first (n = 60) and multiple episodes (n = 59) were recruited from two hospitals in Spain. The Functioning Assessment Short Test (FAST) was used to assess functioning. The Hamilton Depression Rating Scale (HAMD) and the Young Mania Rating Scale (YMRS) were administered to assess mood symptoms.
Results: As expected, patients with first episode experienced a greater functioning compared to patients with multiple episodes (11.26 ± 10.94 vs. 26.91 ± 13.96; t = 6.436, P < 0.001). There were significant demographic and clinical differences between both groups. Baseline depressive symptoms (F = 9.553, df = 4, 102; P < 0.001) and age (F = 14.145, df = 4, 103; P < 0.001) were significantly associated with poor functional recovery at 6‐month and 12‐month assessment, respectively, in a group of patients with multiple episodes.
Conclusion: Our data give support to the model of staging in bipolar disorder, showing that the enduring neurotoxicity of repeated episodes may contribute to sustained impairment in multiple areas of psychosocial functioning.
The size-dependent and shape-dependent characteristics that distinguish nanoscale materials from bulk solids arise from constraining the dimensionality of an inorganic structure
. As a consequence, ...many studies have focused on rationally shaping these materials to influence and enhance their optical, electronic, magnetic and catalytic properties
. Although a select number of stable clusters can typically be synthesized within the nanoscale regime for a specific composition, isolating clusters of a predetermined size and shape remains a challenge, especially for those derived from two-dimensional materials. Here we realize a multidentate coordination environment in a metal-organic framework to stabilize discrete inorganic clusters within a porous crystalline support. We show confined growth of atomically defined nickel(II) bromide, nickel(II) chloride, cobalt(II) chloride and iron(II) chloride sheets through the peripheral coordination of six chelating bipyridine linkers. Notably, confinement within the framework defines the structure and composition of these sheets and facilitates their precise characterization by crystallography. Each metal(II) halide sheet represents a fragment excised from a single layer of the bulk solid structure, and structures obtained at different precursor loadings enable observation of successive stages of sheet assembly. Finally, the isolated sheets exhibit magnetic behaviours distinct from those of the bulk metal halides, including the isolation of ferromagnetically coupled large-spin ground states through the elimination of long-range, interlayer magnetic ordering. Overall, these results demonstrate that the pore environment of a metal-organic framework can be designed to afford precise control over the size, structure and spatial arrangement of inorganic clusters.
In the transition to a clean-energy future, CO2 separations will play a critical role in mitigating current greenhouse gas emissions and facilitating conversion to cleaner-burning and renewable ...fuels. New materials with high selectivities for CO2 adsorption, large CO2 removal capacities, and low regeneration energies are needed to achieve these separations efficiently at scale. Here, we present a detailed investigation of nine diamine-appended variants of the metal–organic framework Mg2(dobpdc) (dobpdc4– = 4,4′-dioxidobiphenyl-3,3′-dicarboxylate) that feature step-shaped CO2 adsorption isotherms resulting from cooperative and reversible insertion of CO2 into metal–amine bonds to form ammonium carbamate chains. Small modifications to the diamine structure are found to shift the threshold pressure for cooperative CO2 adsorption by over 4 orders of magnitude at a given temperature, and the observed trends are rationalized on the basis of crystal structures of the isostructural zinc frameworks obtained from in situ single-crystal X-ray diffraction experiments. The structure–activity relationships derived from these results can be leveraged to tailor adsorbents to the conditions of a given CO2 separation process. The unparalleled versatility of these materials, coupled with their high CO2 capacities and low projected energy costs, highlights their potential as next-generation adsorbents for a wide array of CO2 separations.
The syntheses and magnetic properties of six new compounds featuring the radical-bridged dilanthanide complexes (Cp* sub(2)Ln) sub(2)( mu -t ppz&z.rad; ) super(+) (Ln = Gd, 1; Tb, 2; Dy, 3; tppz = ...2,3,5,6-tetra(2-pyridyl)pyrazine) and (Cp* sub(2)Ln) sub(2)( mu -t ppz&z.rad; ) super(-) (Ln = Gd, 4; Tb, 5, Dy, 6) are reported. Cyclic voltammograms for compounds 1-3 reveal that the tppz ligand can reversibly undergo multiple redox changes. Hence, in the two sets of compounds isolated, 1-3 and 4-6, the redox-active ligand tppz exists in the monoanionic (tppz&z.rad; super(-)) and trianionic (tppz&z.rad; super(3-)) forms, respectively. Substantial Ln super(III)-tppz&z.rad; super(-) exchange coupling is found for the cationic tppz&z.rad; super(-) radical-bridged species of 1-3, as suggested by a rise in chi sub(M)T at low temperatures. For the Gd compound 1, fits to the data yielded a coupling constant of J= -6.91(4) cm super(-1), revealing antiferromagnetic coupling to give an S= 13/2 ground state. Both of the Tb super(III) and Dy super(III)-containing compounds 2 and 3 exhibit single-molecule magnet behavior under zero applied dc field. Importantly, the Dy congener shows a divergence of the field-cooled and zero-field-cooled dc susceptibility data at 2.8 K and magnetic hysteresis below 3.25 K. Interestingly, the coupling constant of J= -6.29(3) cm super(-1) determined for the trianionic tppz&z.rad; super(3-) radical-bridged Gd compound 4 is of similar magnitude to that of the tppz&z.rad; super(-)-bridged analogue 1. However, the anionic tppz&z.rad; super(3-)-bridged species containing Tb super(III) and Dy super(III) centers, compounds 5 and 6, do not exhibit slow magnetization dynamics under zero and applied dc fields. Computational results indicate a doublet ground state for the bridging tppz&z.rad; super(3-) unit, with a different distribution for the spin density orientation towards the Ln super(III) centers. These results have important implications for the future design of molecule-based magnets incorporating exchange-coupled lanthanide-radical species.
The development of materials that reversibly store high densities of thermal energy is critical to the more efficient and sustainable utilization of energy. Herein, we investigate metal–organic ...compounds as a new class of solid–liquid phase-change materials (PCMs) for thermal energy storage. Specifically, we show that isostructural series of divalent metal amide complexes featuring extended hydrogen bond networks can undergo tunable, high-enthalpy melting transitions over a wide temperature range. Moreover, these coordination compounds provide a powerful platform to explore the specific factors that contribute to the energy density and entropy of metal–organic PCMs. Through a systematic analysis of the structural and thermochemical properties of these compounds, we investigated the influence of coordination bonds, hydrogen-bond networks, neutral organic ligands, and outer-sphere anions on their phase-change thermodynamics. In particular, we identify the importance of high densities of coordination bonds and hydrogen bonds to achieving a high PCM energy density, and we show how metal-dependent changes to the local coordination environment during melting impact the entropy and enthalpy of metal–organic PCMs. These results highlight the potential of manipulating order–disorder phase transitions in metal–organic materials for thermal energy storage.
The Global Reach of the 26 December 2004 Sumatra Tsunami Titov, Vasily; Rabinovich, Alexander B.; Mofjeld, Harold O. ...
Science (American Association for the Advancement of Science),
09/2005, Letnik:
309, Številka:
5743
Journal Article
Recenzirano
Odprti dostop
Numerical model simulations, combined with tide-gauge and satellite altimetry data, reveal that wave amplitudes, directionality, and global propagation patterns of the 26 December 2004 Sumatra ...tsunami were primarily determined by the orientation and intensity of the offshore seismic line source and subsequently by the trapping effect of mid-ocean ridge topographic waveguides.
Genera of phytopathogenic fungi: GOPHY 3 Marin-Felix, Y.; Hernández-Restrepo, M.; Iturrieta-González, I. ...
Studies in mycology,
09/2019, Letnik:
94, Številka:
1
Journal Article
Recenzirano
Odprti dostop
This paper represents the third contribution in the Genera of Phytopathogenic Fungi (GOPHY) series. The series provides morphological descriptions, information about the pathology, distribution, ...hosts and disease symptoms for the treated genera, as well as primary and secondary DNA barcodes for the currently accepted species included in these. This third paper in the GOPHY series treats 21 genera of phytopathogenic fungi and their relatives including: Allophoma, Alternaria, Brunneosphaerella, Elsinoe, Exserohilum, Neosetophoma, Neostagonospora, Nothophoma, Parastagonospora, Phaeosphaeriopsis, Pleiocarpon, Pyrenophora, Ramichloridium, Seifertia, Seiridium, Septoriella, Setophoma, Stagonosporopsis, Stemphylium, Tubakia and Zasmidium. This study includes three new genera, 42 new species, 23 new combinations, four new names, and three typifications of older names.
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