16 research outputs found
Tris(1,10-phenanthroline-Îș2 N,NâČ)iron(II) bisÂ[(1,10-phenanthroline-Îș2 N,NâČ)tetraÂkisÂ(thioÂcyanato-ÎșN)chromate(III)] acetonitrile trisÂolvate monohydrate
Single crystals of the title heterometallic compound, [Fe(C12H8N2)3][Cr(NCS)4(C12H8N2)]2·3CH3CN·H2O or [Fe(Cphen)3][Cr(NCS)4(phen)]2·3CH3CN·H2O, were preÂpared using the one-pot open-air reaction of iron powder, Reineckes salt and 1,10-phenanthroline (phen) in acetonitrile. The asymetric unit consists of an [Fe(phen)3]2+ cation, two [Cr(phen)(NCS)4]â anions, three acetonitrile solvent molÂecules and a water molÂecule. The Fe and Cr atoms both show a slightly distorted octaÂhedral FeN6 and CrN6 coordination geometry with adjacent angles in the range 79.67â
(12)â95.21â
(12)°. No classical hydrogen bonding involving the water molecule is observed
Global maps of soil temperature
Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-kmÂČ resolution for 0â5 and 5â15 cm soil depth. These maps were created by calculating the difference (i.e., offset) between in-situ soil temperature measurements, based on time series from over 1200 1-kmÂČ pixels (summarized from 8500 unique temperature sensors) across all the worldâs major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in-situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications
Global maps of soil temperature
Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0â5 and 5â15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world\u27s major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (â0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications
Global maps of soil temperature.
Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0-5 and 5-15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications
Elucidating the Structural Evolution of a Highly Porous Responsive MetalâOrganic Framework (DUT-49(M)) upon Guest Desorption by Time-Resolved in Situ Powder X-ray Diffraction
Removal of the guest molecules from the pores of metalâorganic frameworks (MOFs) is one of the critical steps in particular for highly porous frameworks associated with high internal stress. In the case of isostructural mesoporous DUT-49(M) (M = Cu, Ni, Mn, Fe, Co, Zn, Cd) frameworks, only DUT-49(Cu) and DUT-49(Ni) could be successfully desolvated so far and only by using supercritical activation. To get a deeper insight into the processes occurring upon the desorption of the solvent from the pores of DUT-49(M), the desolvation was monitored in situ by synchrotron powder X-ray diffraction (PXRD). Analysis of the time-resolved PXRD data shows the full structural transformation pathway of the solid, which involves continuous and discontinuous phase transitions from the open pore (op) to the intermediate pore (ip) phase and from the ip to the contracted pore (cp) phase for DUT-49(Cu) and DUT-49(Ni). For DUT-49(Zn), the op to ip transition is directly followed by amorphization of the framework. All other frameworks show direct amorphization of the op phase
Quasi-continuous cooperative adsorption mechanism in crystalline nanoporous materials
Phase behavior of confined fluids adsorbed in na-nopores differs significantly from their bulk coun-terparts and depends on the chemical and structural properties of the confining structures. In general, phase transitions in nanoconfined fluids are reflect-ed in stepwise adsorption isotherms with a pro-nounced hysteresis. Here, we show experimental evidence and in silico interpretation of the reversi-ble stepwise adsorption isotherm which is observed when methane is adsorbed in the rigid, crystalline metal-organic framework IRMOF-1 (MOF-5). In a very narrow range of pressures, the adsorbed fluid undergoes a structural and highly cooperative re-construction and transition between low-density and high-density nanophases, as a result of the competition between the fluid-framework and flu-id-fluid interactions. This mechanism evolves with temperature: below 110 K a reversible stepwise iso-therm is observed, which is a result of the bimodal distribution of the coexisting nanophases. This temperature may be considered as a critical temper-ature of methane confined to nanopores of IRMOF-1. Above 110 K, as the entropy contribution in-creases, the isotherm shape transforms to a common continuous S-shaped form that is characteristic to a gradual densification of the adsorbed phase as the pressure increases
Novel Heterometallic Schiff Base Complexes Featuring Unusual Tetranuclear {Co<sup>III</sup><sub>2</sub>Fe<sup>III</sup><sub>2</sub>(Ό-O)<sub>6</sub>} and Octanuclear {Co<sup>III</sup><sub>4</sub>Fe<sup>III</sup><sub>4</sub>(Ό-O)<sub>14</sub>} Cores: Direct Synthesis, Crystal Structures, and Magnetic Properties
A one-pot reactions of cobalt powder with ironÂ(II) chloride
in dimethylformamide
(DMF; <b>1</b>) or dimethyl sulfoxide (DMSO; <b>2</b>)
solutions of polydentate salicylaldimine Schiff base ligands (H<sub>2</sub>L<sup>1</sup>, <b>1</b>; H<sub>4</sub>L<sup>2</sup>, <b>2</b>) based on 2-aminobenzyl alcohol (<b>1</b>) or trisÂ(hydroxymethyl)Âaminomethane
(<b>2</b>), formed in situ, yielded two novel heterometallic
complexes, [Co<sup>III</sup><sub>2</sub>Fe<sup>III</sup><sub>2</sub>(L<sup>1</sup>)<sub>6</sub>]·4DMF (<b>1</b>) and [Co<sup>III</sup><sub>4</sub>Fe<sup>III</sup><sub>4</sub>(HL<sup>2</sup>)<sub>8</sub>(DMSO)<sub>2</sub>]·18DMSO (<b>2</b>). Crystallographic
investigations revealed that
the molecular structure of <b>1</b> is based on a tetranuclear
core, {Co<sup>III</sup><sub>2</sub>Fe<sup>III</sup><sub>2</sub>(Ό-O)<sub>6</sub>}, with a chainlike metal arrangement, while the structure
of <b>2</b> represents the first example of a heterometallic
octanuclear core, {Co<sup>III</sup><sub>4</sub>Fe<sup>III</sup><sub>4</sub>(Ό-O)<sub>14</sub>}, with a quite rare manner of metal
organization, formed
by two pairs of {CoFeÂ(HL<sup>2</sup>)<sub>2</sub>} and {CoFeÂ(HL<sup>2</sup>)<sub>2</sub>(DMSO)} moieties, which are joined by O bridges
of the Schiff base ligands. Variable-temperature (1.8â300 K)
magnetic susceptibility measurements showed a decrease of the Ό<sub>B</sub> value at low temperature, indicative of
antiferromagnetic coupling (<i>J</i>/<i>hc</i> = â32 cm<sup>â1</sup> in <b>1</b>; <i>J</i>/<i>hc</i> = â20 cm<sup>â1</sup> in <b>2</b>) between the Fe<sup>III</sup> magnetic centers
in both compounds. For <b>2</b>, three <i>J</i> constants
between Fe<sup>III</sup> centers were assumed to be identical. High-frequency
electron paramagnetic resonance spectra allowed one to find spin Hamiltonian
parameters in the coupled-spin triplet and quintet states of <b>1</b> and estimate them in <b>2</b>. The âouterâ
and âinnerâ Fe atoms in <b>2</b> appeared separately
in the MoÌssbauer spectra