Seco et al examine the assignment of the absolute configuration of polyfunctional compounds by nuclear magnetic resonance (NMR) using chiral derivatizing agents.
Herein, we describe and study a new family of isostructural multifunctional metal–organic frameworks (MOFs) with the formula {Ln5L6(OH)3(DMF)3·5H2O} n (where (H2L) is 3-amino-4-hydroxybenzoic acid ...ligand) for magnetism and photoluminescence. Interestingly, three of the materials (Dy-, Er-, and Yb-based MOFs) present single-molecule magnet (SMM) behavior derived from the magnetic anisotropy of the lanthanide ions as a consequence of the adequate electronic distribution of the coordination environment. Additionally, photoluminescence properties of the ligand in combination with Eu and Tb counterparts were studied, including the heterometallic Eu–Tb mixed MOF that shows potential as ratiometric luminescent thermometers. Finally, the porous nature of the framework allowed showing the CO2 sorption capacity.
Methods sections are often missing essential details. Methodological shortcut citations, in which authors cite previous papers instead of describing the method in detail, may contribute to this ...problem. This meta-research study used 3 approaches to examine shortcut citation use in neuroscience, biology, and psychiatry. First, we assessed current practices in more than 750 papers. More than 90% of papers used shortcut citations. Other common reasons for using citations in the methods included giving credit or specifying what was used (who or what citation) and providing context or a justification (why citation). Next, we reviewed 15 papers to determine what can happen when readers follow shortcut citations to find methodological details. While shortcut citations can be used effectively, they can also deprive readers of essential methodological details. Problems encountered included difficulty identifying or accessing the cited materials, missing or insufficient descriptions of the cited method, and shortcut citation chains. Third, we examined journal policies. Fewer than one quarter of journals had policies describing how authors should report previously described methods. We propose that methodological shortcut citations should meet 3 criteria; cited resources should provide (1) a detailed description of (2) the method used by the citing authors', and (3) be open access. Resources that do not meet these criteria should be cited to give credit, but not as shortcut citations. We outline actions that authors and journals can take to use shortcut citations responsibly, while fostering a culture of open and reproducible methods reporting.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
As a starting point, a new 3D porous framework with the {CoL·0.5DMF·H
O}
chemical formula (where L = 3-amino-4-hydroxybenzoate) is described. Its performance as a single molecule magnet was explored. ...The study of magnetic properties reveals that Co-MOF shows no frequency-fdependant alternating current (
) signals under zero direct current (
) magnetic field, whereas single-molecule magnet behaviour is achieved when Co
ions are diluted in a Zn
based matrix. Interestingly, this strategy renders a bifunctional Co
Zn
L
material that is also characterized by a strong photoluminescent emitting capacity.
We report two different approaches to isolate neutral and cationic mesocate-type metallosupramolecular architectures derived from coinage monovalent ions. For this purpose, we use a ...thiocarbohydrazone ligand, H2L (1), conveniently tuned with bulky phosphine groups to stabilize the MI ions and prevent ligand crossing to achieve the selective formation of mesocates. The neutral complexes Cu2(HL)2 (2), Ag2(HL)2 (3), and Au2(HL)2 (4) were prepared by an electrochemical method, while the cationic complexes Cu2(H2L)2(PF6)2 (5), Cu2(H2L)2(BF4)2 (6), Ag2(H2L)2(PF6)2 (7), Ag4(HL)2(NO3)2 (8), and Au2(H2L)2Cl2 (9) were obtained by using a metal salt as the precursor. All of the complexes are neutral or cationic dinuclear mesocates, except the silver nitrate derivative, which exhibits a tetranuclear cluster mesocate architecture. The crystal structures of the neutral and cationic copper(I), silver(I), and gold(I) complexes allow us to analyze the influence of synthetic methodology or the counterion role on both the micro- and macrostructures of the mesocates.
Helix sense selection: Tuning the conformational equilibrium of the pendants of poly(phenylacetylene)s allows selection of the helicity of the polymer in a reversible way. Complexation with ...appropriate metal cations (e.g. Ba2+) or changing the polarity of the solvent permits the reversible selection of the desired helix sense. A full picture of the mechanism explaining this phenomenon is presented.
Peripheral venous catheter-associated bloodstream infections (PVC-BSIs) lead to prolonged hospitalization, morbidity and increased costs. The impact of infection-prevention measures on the rate of ...PVC-BSIs in a university hospital in Spain was assessed. An active surveillance programme was initiated in 2015, which revealed a high PVC-BSI incidence ratio (0.48/1000 patient-days). A bundle aimed at nurses, medical staff and patients was implemented, and a Catheter Infection Team (CIT) was set up. The intervention achieved a decrease in PVC-BSI rate: 0.34 in 2016, 0.29 in 2017, and 0.17 in 2018. The decline was greatest for Gram-negative PVC-BSIs (67.6% in 2015, 35.3% in 2018).
The ligand design factors that may influence the isolation of metallosupramolecular helicates or mesocates still deserve to be investigated. In this sense, dinuclear nickel(
ii
), copper(
ii
) and ...zinc(
ii
) compounds were obtained by electrochemical synthesis using a family of five Schiff base ligands, H
2
L
n
(
n
= 1-5), derived from bisphenylmethane and functionalized with bulky
tert
-butyl groups in the periphery and ethyl groups in the spacer. Six of the new complexes were characterized by X-ray crystallography, thus demonstrating that the helicate structure is predominant in the solid state.
1
H NMR studies were performed for the zinc complexes to analyze if the helical architecture of the metal complexes is retained in solution. These studies reveal that the presence of a
tert
-butyl group in the
ortho
position with respect to the OH group is an essential factor identified for the existence of a helicate conformation in solution.
The number and position of bulky groups in the skeleton of the ligand precursor influence whether helicates or mesocates are obtained.
A new porous metal-organic framework (MOF) with the chemical formula Y
5
L
6
(OH)
3
(DMF)
3
·5H
2
O (
1
) (where L = 3-amino-4-hydroxybenzoate) has been prepared by a solvothermal procedure. The ...structural characterization reveals that this material consists of a robust three-dimensional metal-organic framework (MOF) grown with clusters formed by Y(
iii
) and hydroxide anions joined to one another by the ligand, giving rise to an open structure with interconnected microchannels with variable dimensions. This assembled set has shown to possess a fascinating catalytic activity for the cyanosilylation of a broad range of aldehydes and ketones with exceptional recyclability, a solvent-free medium, and one order of magnitude lower catalyst loading compared to all related lanthanide-based MOFs described so far in the literature.
A novel MOF has been synthesized, characterized, and applied in the cyanosilylation of aldehydes and ketones being the first example of an yttrium MOF able to catalyze this reaction.
This work reports on the synthesis and characterization of five enantiomeric pairs of isostructural 3D metal-organic frameworks (MOFs) with the general formula {Ln
2
(μ
4
-tar)
2
(μ-tar)(H
2
O)
2
·
x
...H
2
O}
n
where Ln(
iii
) = Tb (
Tb-L
and
Tb-D
), Dy (
Dy-L
and
Dy-D
), Ho (
Ho-L
and
Ho-D
), Er (
Er-L
and
Er-D
) and Tm (
Tm-L
and
Tm-D
); tar = tartrate (
d
- or
l
-) and
x
= 3 or 4 depending on the counterpart, which possess interesting luminescence and magnetic properties. These MOFs undergo progressive and reversible dehydration processes upon controlled heating yielding three crystalline phases (
Ln-L′
,
Ln-L′′
and
Ln-L′′′
). Alternating current magnetic measurements on Tb, Dy and Er-based compounds exhibit field induced single-molecule magnet behavior dominated by QTM, which is partially suppressed when diluted on a Y-based matrix. Tartrate ligands show poor room temperature sensitization of Tb and Dy centers that is enhanced at low temperature (10 K), even enabling weak Tm-based emission. More interestingly, the dehydration modulates both magnetic and photoluminescence properties on the basis of both the distortions occurring in the coordination shells and a decrease of water molecules acting as quenchers, respectively, endowing these materials with potential humidity sensing capacity. Remarkably, the Tb-based MOF shows circularly polarized luminescence (CPL), being one of the examples of this very scarce family of CPL emitters reported so far.
Chiral 3D microporous lanthanide and tartrate-based MOFs with thermally induced modulation of magnetic/luminescence properties and chiroptical activity.
