357 research outputs found
1862-03-22 George Anson writes General Hodsdon regarding supplies for Eli Rowe of Brewer
https://digitalmaine.com/cw_me_1st_cav/1230/thumbnail.jp
Synthesis and Supramolecular Structure of a (5-(3-(1H-tetrazol-5-yl)phenyl)-1H-tetrazole) Cobalt Complex
The reaction of CoCl2·6H2O with m-BDTH2 (1,3-benzeneditetrazol-5-yl) leads to [Co(C8H6N8)2(H2O)2(CH3CN)2]Cl2 (1). Both tetrazolic groups remain protonated existing in a 1H tautomeric form. A trifurcated chlorine atom and stacking interactions assemble compound 1 into a three-dimensional network
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An undecanuclear ferrimagnetic Cu9Dy2 SMM achieved through ligand fine-tuning
We describe the concept of increasing the nuclearity of a previously reported high-spin Cu5Gd2 core using a âfine tuningâ ligand approach. Thus two Cu9Ln2 coordination clusters, with Ln = Dy (1), Gd(2) were synthesized with the Gd compound having a ground spin state of 17/2 and the Dy analogue showing SMM behavior in zero field
Tetranuclear CuII2DyIII2 coordination cluster as Suzuki (CâC) coupling reaction promoter
The air stable and high yielding tetranuclear coordination cluster [CuII2DyIII2L4(NO3)2(CH3CN)2]·2(CH3CN) promotes the Suzuki coupling reaction of phenylboronic acid with substituted aryl halides in environmentally benign conditions
Synthesis, structure and electrochemical characterization of the isopolytungstate (W4O16) held by MnII anchors within a superlacunary crown heteropolyanion {P8W48}
An isopolyanion {W4O16} within archetypal {P8W48} heteropolyanion assembly [(P8W48O184)(W4O16)K10Li4Mn10Na(H2O)50Cl2] 15- (Mn10W4-P8W48) has been synthesized by the reaction of the cyclic superlacunary anion [H7P8W48O184] 33â and Mn(ClO4)2.6H2O in I M LiCl soultion medium at pH 8. The isolated compound has been characterized by single crystal X-ray crystallography, powder X-ray diffraction (PXRD), Fourier-transform infrared (FTIR) spectroscopy, elemental analysis and thermogravimetric analysis. Electrochemical studies were also performed on Mn10W4-P8W48 confirmed the presence of Mn centres bonded to the tunsgtic framework. The novel polyanion [(P8W48O184)(W4O16)K10Li4Mn10Na(H2O)50Cl2] 15- is the first example of macrocyclic complex where an isopolyanion (W4O16) 8- is embedded within in the inner cavity of the {P8W48} and is placed in position by six MnII cations as anchors. Whereas, the exocyclic coordination of the four MnII atoms to {P8W48} yields extended structure by linking neighbouring polyanions through {WâOâMnâOâW} bridges. Further, the polyanion Mn10W4-P8W48 is the first derivative of {P8W48} with six MnII ions (largest) coordinated to the inner side the crown ring as anchors
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Systematic studies of hexanuclear {MIII4LnIII2} complexes (M = Fe, Ga; Ln = Er, Ho): structures, magnetic properties and SMM behavior
Four isostructural MIII4LnIII2 coordination clusters, [M4Ln2(ÎŒ3-OH)2(nbdea)4(C6H5COO)8]âąMeCN (M = Fe, Ln = Er (1); M = Ga, Ln = Er (2); M = Fe, Ln = Ho (3); M = Ga, Ln = Ho (4)) have been synthesized and characterized. Single-crystal X-ray diffraction and X-ray powder diffraction studies revealed that all four compounds crystallize isomorphously to each other, and to the previously reported MIII4DyIII2 (M = Fe or Ga) and FeIII4YIII2 analogues. DC magnetic susceptibility measurements for compounds 1-4, taken in combination with those for the FeIII4YIII2 analogue, indicated that the interactions between ErIII ions are weakly ferromagnetic and the FeIII-ErIII interactions are very weakly antiferromagnetic, while the HoIII-HoIII and FeIII-HoIII interactions are both negligible. By comparison, for the FeIII4DyIII2 analogue, the DyIII-DyIII interactions are antiferromagnetic while the FeIII-DyIII are ferromagnetic. Both Er analogues 1 and 2 display single-molecule magnet (SMM) behavior with the effective energy barrier Ueff increasing from 12.8 K (for Fe4Er2 1) to 53.5 K (for Ga4Er2 2), indicating that the very weak 3d-4f interaction enhances the QTM effect
The effect of reionization on direct measurements of the mean free path
Recent measurements of the ionizing photon mean free path (MFP) based on
composite quasar spectra may point to a late end to reionization at .
These measurements are challenging, however, because they rely on assumptions
about the proximity zones of the quasars in the analysis. For example, some of
the quasars in the composite might have been close to large-scale
regions where reionization was still ongoing ("neutral islands"), and it is
unclear how this would affect the measurements. We address the question here
with mock MFP measurements from radiative transfer simulations. We find that,
even in the presence of neutral islands, the inferred MFP tracks to within the true attenuation scale of the spatially averaged IGM, which includes
opacity from both the ionized medium and the islands. During reionization, this
scale is always shorter than the MFP in the ionized medium. The inferred MFP is
sensitive at the level to assumptions about the quasar environments
and lifetimes for realistic models. We demonstrate that future analyses with
improved data may require explicitly modeling the effects of neutral islands on
the composite spectra, and we outline a method for doing this. Lastly, we
quantify the effects of neutral islands on Lyman-series transmission, which has
been modeled with optically thin simulations in previous MFP analyses. Neutral
islands can suppress transmission at \r{A}
significantly, up to a factor of 2 for in a plausible
reionization scenario, owing to absorption by many closely spaced lines as
quasar light redshifts into resonance. However, the suppression is almost
entirely degenerate with the spectrum normalization, thus does not
significantly bias the inferred MFP.Comment: 11 pages, 8 figures, submitted to MNRA
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