68 research outputs found
Synthesis and Structural Characterization of a Metal Cluster and a Coordination Polymer Based on the [Mn6(μ4-O)2]10+ Unit
A new 1-D coordination polymer {[Mn6O2(O2CMe)10(H2O)4]·2.5H2O}∞ (1·2.5H2O)∞ and the cluster [Mn6O2(O2(O2CPh)10 (py)2(MeCN)(H2O)]·2MeCN (2·2MeCN) are reported. Both compounds were synthesized by room temperature reactions of [Mn3(μ3-O)(O2CR)6(L)2(L′)] (R = Me, L = L′ = py, (1·2.5H2O)∞; R = Ph, L = py, L′ = H2O, 2·2MeCN) in the presence of 3-hydroxymethylpyridine (3hmpH) in acetonitrile. The structures of these complexes are based on hexanuclear mixed-valent manganese carboxylate clusters containing the [Mn4IIMn2III(μ4-O)2]10+ structural core. (1·2.5H2O)∞ consists of zigzag chain polymers constructed from [Mn6O2(O2CMe)10(H2O)4] repeating units linked through acetate ligands, whereas 2·2MeCN comprises a discrete Mn6-benzoate cluster
(2E,4E,6E)-3-Methyl-7-(pyren-1-yl)octa-2,4,6-trienoic acid
The title compound, C25H20O2, was synthesized by a Wittig reaction between triphenyl[1-(pyren-1-yl)ethyl]phosphonium bromide and ethyl (2E,4E)-3-methyl-6-oxohexa-2,4-dienoate, in the presence of n-butyl lithium, followed by saponification. It was obtained pure in the all-trans configuration following crystallization from ethyl acetate. The asymmetric unit contains two independent molecules (A and B), which are arranged almost parallel to each other within the crystal structure. The triene chain is not coplanar with the pyrene ring system, forming dihedral angles of 52.8 (1) and 42.2 (1)° for molecules A and B, respectively. Intermolecular hydrogen bonds between the carboxyl groups of the molecules link them into centrosymmetric pairs, AA and BB, each with the R
2
2(8) graph-set motif
Tricyclo[3.3.1.03,7]nonane-3,7-diyl bis(methanesulfonate)
The crystal structure of the title compound, C11H18O6S2, was determined to investigate the effect of the eclipsed mesyl groups on the bond length of the vicinal quaternary C atoms. The two quaternary C atoms of the noradamantane skeleton and the two O atoms to which they are connected all located essentially in the same plane [maximum deviation 0.01 Å], resulting in an eclipsing conformation of the C—O bonds. The C—C bond of the quaternary C atoms is 1.597 (3) Å is considerably longer than the other C—C bonds of the molecule
Chemically modified electrodes with MOFs for the determination of inorganic and organic analytes via voltammetric techniques: a critical review
Voltammetric analytical techniques combine exceptional sensitivity, low
cost, portability and capability for simultaneous determination of
multiple analytes. The sensitivity of voltammetric analysis is largely
determined by the efficiency of the working electrode. Electrodes
modified with metal organic frameworks (MOFs) seem particularly
promising for use in the analysis of a series of important inorganic and
organic analytes. Nevertheless, research on chemically modified
electrodes with MOFs is still in its infancy. In this critical review,
we present the current status of research related to MOF-modified
electrodes highlighting the respective MOF-modified electrodes which are
based on MOFs that show exceptional chemical stability or/and sorption
capability towards the targeted analytes. We also provide perspectives
for future research aiming at motivating additional scientists to be
involved in this exciting field of MOF-based electroanalytical sensors
Unravelling the mechanism of water sensing by the Mg2+ dihydroxy-terephthalate MOF (AEMOF-1 ‘)
In this contribution we build upon our previous work on the MOF
[Mg(H(2)dhtp)(H2O)(2)]center dot DMAc (AEMOF-1 center dot DMAc) and
its activated dry version AEMOF-1 ‘ which has been shown to exhibit
excellent luminescence sensing properties towards water in organic
solvents. We demonstrate through combined structural and photophysical
studies that the observed changes in the fluorescence properties of
AEMOF-1 ‘ upon hydration arise from a structural transformation to the
mononuclear complex [Mg(H(2)dhtp)(H2O)(5)]center dot H2O (H(4)dhtp =
2,5-dihydroxyterepthalic acid) (1). In the latter complex, excited state
intramolecular proton transfer (ESIPT) is strongly favoured thereby
leading to enhanced and red shifted emission in comparison to AEMOF-1
center dot DMAc. Powder X-ray diffraction measurements confirmed that
complex 1 is identical to the hydrated form of AEMOF-1 center dot DMAc.
As in the case of AEMOF-1 ‘, the dry form of complex 1 (1 ‘) is also an
effective sensor for the determination of traces of water in
tetrahydrofuran (THF). This work demonstrates that the same chromophore
may exhibit very different emission properties when it exists in
different chemical environments and that these transformations may be
controlled and utilized in water sensing applications
Layered Metal Sulfides Capture Uranium from Seawater
Uranium is the main source for nuclear energy but also
one of the
most toxic heavy metals. The current methods for uranium removal from
water present limitations, such as narrow pH operating range, limited
tolerance to high salt concentrations, or/and high cost. We show here
that a layered sulfide ion exchanger K<sub>2</sub>MnSn<sub>2</sub>S<sub>6</sub> (KMS-1) overcomes these limitations and is exceptionally
capable in selectively and rapidly sequestering high (ppm) as well
as trace (ppb) quantities of UO<sub>2</sub><sup>2+</sup> under a variety
of conditions, including seawater. KMS-1 can efficiently absorb the
naturally occurring U traces in seawater samples. The results presented
here reveal the exceptional potential of sulfide-based ion-exchangers
for remediating of uranium-containing wastes and groundwater and for
extracting uranium from the sea
Layered Metal Sulfides Capture Uranium from Seawater
Uranium is the main source for nuclear energy but also
one of the
most toxic heavy metals. The current methods for uranium removal from
water present limitations, such as narrow pH operating range, limited
tolerance to high salt concentrations, or/and high cost. We show here
that a layered sulfide ion exchanger K<sub>2</sub>MnSn<sub>2</sub>S<sub>6</sub> (KMS-1) overcomes these limitations and is exceptionally
capable in selectively and rapidly sequestering high (ppm) as well
as trace (ppb) quantities of UO<sub>2</sub><sup>2+</sup> under a variety
of conditions, including seawater. KMS-1 can efficiently absorb the
naturally occurring U traces in seawater samples. The results presented
here reveal the exceptional potential of sulfide-based ion-exchangers
for remediating of uranium-containing wastes and groundwater and for
extracting uranium from the sea
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