A series of dysprosium(iii) metallocenium salts, Dy(Cp
)
B(C
F
)
(R = H (
), Me (
), Et (
), iPr (
)), was synthesized by reaction of DyI
with the corresponding known NaCp
(R = H, iPr) and novel ...NaCp
(R = Me, Et) salts at high temperature, followed by iodide abstraction with H(SiEt
)
B(C
F
)
. Variation of the substituents in this series results in substantial changes in molecular structure, with more sterically-encumbering cyclopentadienyl ligands promoting longer Dy-C distances and larger Cp-Dy-Cp angles. Dc and ac magnetic susceptibility data reveal that these structural changes have a considerable impact on the magnetic relaxation behavior and operating temperature of each compound. In particular, the magnetic relaxation barrier increases as the Dy-C distance decreases and the Cp-Dy-Cp angle increases. An overall 45 K increase in the magnetic blocking temperature is observed across the series, with compounds
exhibiting the highest 100 s blocking temperatures yet reported for a single-molecule magnet. Compound
possesses the highest operating temperature of the series with a 100 s blocking temperature of 62 K. Concomitant increases in the effective relaxation barrier and the maximum magnetic hysteresis temperature are observed, with
displaying a barrier of 1468 cm
and open magnetic hysteresis as high as 72 K at a sweep rate of 3.1 mT s
. Magneto-structural correlations are discussed with the goal of guiding the synthesis of future high operating temperature Dy
metallocenium single-molecule magnets.
Quantum tunneling of magnetization (QTM) steps have been observed for a mixed 3d–4f single‐molecule magnet for the first time in the hysteresis loops of {Mn12Gd}. This phenomenon is assigned to ...larger than usual exchange coupling of the 4f atom with the {Mn12} shell. This improved quantum behavior for the important class of SMMs opens up the prospects for its detailed study using hysteresis methods. Gd purple, Mn(II) yellow, Mn(III) blue, O red, N green.
As an alternative technology to energy intensive distillations, adsorptive separation by porous solids offers lower energy cost and higher efficiency. Herein we report a topology-directed design and ...synthesis of a series of Zr-based metal-organic frameworks with optimized pore structure for efficient separation of C6 alkane isomers, a critical step in the petroleum refining process to produce gasoline with high octane rating. Zr
O
(OH)
(bptc)
adsorbs a large amount of n-hexane but excluding branched isomers. The n-hexane uptake is ~70% higher than that of a benchmark adsorbent, zeolite-5A. A derivative structure, Zr
O
(OH)
(H
O)
(abtc)
, is capable of discriminating all three C6 isomers and yielding a high separation factor for 3-methylpentane over 2,3-dimethylbutane. This property is critical for producing gasoline with further improved quality. Multicomponent breakthrough experiments provide a quantitative measure of the capability of these materials for separation of C6 alkane isomers. A detailed structural analysis reveals the unique topology, connectivity and relationship of these compounds.
A bis(pyrazolylpyridyl) ligand, L, containing a central photochromic dithienylethene spacer predictably forms a ferrous Fe2L34+ helicate exhibiting spin crossover (SCO). In solution, the compound ...Fe2L3(ClO4)4 (1) preserves the magnetic properties and is fluorescent. The structure of 1 is photo‐switchable following the reversible ring closure/opening of the central dithienylethene via irradiation with UV/visible light. This photoisomerization switches on and off some emission bands of 1 and provides a means of externally manipulating the magnetic properties of the assembly.
Fluoro‐photo‐magnificence: An iron‐containing spin‐crossover molecule has been synthesized that contains a photoswitchable unit. This unit allows its magnetic properties and its fluorescent response using light to be reversibly tuned.
We successfully assembled the photocatalytic titanium-oxo cluster and photosensitizing porphyrinic linker into a metal-organic framework (MOF), namely PCN-22. A preformed titanium-oxo carboxylate ...cluster is adopted as the starting material to judiciously control the MOF growth process to afford single crystals. This synthetic method is useful to obtain highly crystalline titanium MOFs, which has been a daunting challenge in this field. Moreover, PCN-22 demonstrated permanent porosity and photocatalytic activities toward alcohol oxidation.
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