排序方式: 共有154条查询结果,搜索用时 31 毫秒
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Dr. Ross McLellan Maria A. Palacios Dr. Christine M. Beavers Dr. Simon J. Teat Dr. Stergios Piligkos Prof. Euan K. Brechin Dr. Scott J. Dalgarno 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(7):2804-2812
Methylene‐bridged calix[4]arenes have emerged as extremely versatile ligand supports in the formation of new polymetallic clusters possessing fascinating magnetic properties. Metal ion binding rules established for this building block allow one to partially rationalise the complex assembly process. The ability to covalently link calix[4]arenes at the methylene bridge provides significantly improved control over the introduction of different metal centres to resulting cluster motifs. Clusters assembled from bis‐calix[4]arenes and transition metal ions or 3d‐4f combinations display characteristic features of the analogous calix[4]arene supported clusters, thereby demonstrating an enhanced and rational approach towards the targeted synthesis of complex and challenging structures. 相似文献
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Facile Interchange of 3d and 4f Ions in Single‐Molecule Magnets: Stepwise Assembly of [Mn4], [Mn3Ln] and [Mn2Ln2] Cages within Calix[4]arene Scaffolds 下载免费PDF全文
Dr. Maria A. Palacios Dr. Ross McLellan Dr. Christine M. Beavers Dr. Simon J. Teat Dr. Høgni Weihe Dr. Stergios Piligkos Dr. Scott J. Dalgarno Prof. Euan K. Brechin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(31):11212-11218
The central MnII ions in a series of calix[4]arene‐stabilised butterflies can be sequentially replaced with LnIII ions, maintaining the structural integrity of the molecule but transforming its magnetic properties. The replacement of MnII for GdIII allows for the examination of the transferability of spin‐Hamiltonian parameters within the family as well as permitting their reliable determination. The introduction of the 4f ions results in weaker intramolecular magnetic exchange, an increase in the number of low‐lying excited states, and an increase in magnetisation relaxation, highlighting the importance of exchange over single‐ion anisotropy for the observation of SMM behaviour in this family of complexes. The presence of the [TMII/III(TBC[4])(OH)(solvent)] metalloligand (TM=transition metal, TBC=p‐tBu‐calix[4]arene) suggests that magnetic calix[n]arene building blocks can be employed to encapsulate a range of different “guests” within structurally robust “hosts”. 相似文献
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Ross S. Winter Dr. Jun Yan Dr. Christoph Busche Dr. Jennifer S. Mathieson Dr. Alessandro Prescimone Prof. Euan K. Brechin Dr. De‐Liang Long Prof. Leroy Cronin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(9):2976-2981
Two near isomeric clusters containing a novel {Mn8W4} Keggin cluster within a [W36Mn10Si4O136(OH)4(H2O)8]24? cluster are reported: K10Li14 [W36Si4O136MnII10(OH)4(H2O)8] ( 1 ) and K10Li13.5Mn0.25[W36Si4O136MnII10(OH)4(H2O)8] ( 1′ ). Bulk characterization of the clusters has been carried out by single crystal X‐ray structure analysis, ICP‐MS, TGA, ESI‐MS, CV and SQUID‐magnetometer analysis. X‐ray analysis revealed that 1′ has eight positions within the central Keggin core that were disordered W/Mn whereas 1 contained no such disorder. This subtle difference is due to a differences is how the two clusters assemble and recrystallize from the same mother liquor and represents a new type of isomerism. The rapid recrystallization process was captured via digital microscopy and this uncovered two “intermediate” types of crystal which formed temporarily and provided nucleation sites for the final clusters to assemble. The intermediates were investigated by single crystal X‐ray analysis and revealed to be novel clusters K4Li22[W36Si4Mn7O136(H2O)8]?56 H2O ( 2 ) and Mn2K8Li14[W36Si4Mn7O136(H2O)8]?45 H2O ( 3 ). The intermediate clusters contained different yet related building blocks to the final clusters which allowed for the postulation of a mechanism of assembly. This demonstrates a rare example where the use X‐ray crystallography directly facilitated understanding the means by which a POM assembled. 相似文献
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Combining Complementary Ligands into one Framework for the Construction of a Ferromagnetically Coupled [MnIII12] Wheel 下载免费PDF全文
Dr. Sergio Sanz Jamie M. Frost Thayalan Rajeshkumar Dr. Scott J. Dalgarno Dr. Gopalan Rajaraman Dr. Wolfgang Wernsdorfer Prof. Jürgen Schnack Dr. Paul. J. Lusby Prof. Euan K. Brechin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(11):3010-3013
Phenolic oxime and diethanolamine moieties have been combined into one organic framework, resulting in the formation of a novel ligand type that can be employed to construct a rare and unusual dodecametallic Mn wheel, within which nearest neighbours are coupled ferromagnetically. 相似文献
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Alice E. Dearle Daniel J. Cutler Hector W. L. Fraser Sergio Sanz Edward Lee Sourav Dey Ismael F. Diaz‐Ortega Gary S. Nichol Hiroyuki Nojiri Marco Evangelisti Gopalan Rajaraman Jürgen Schnack Leroy Cronin Euan K. Brechin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(47):17059-17062
The dissolution of anhydrous iron bromide in a mixture of pyridine and acetonitrile, in the presence of an organic amine, results in the formation of an [Fe34] metal oxide molecule, structurally characterised by alternate layers of tetrahedral and octahedral FeIII ions connected by oxide and hydroxide ions. The outer shell of the complex is capped by a combination of pyridine molecules and bromide ions. Magnetic data, measured at temperatures as low as 0.4 K and fields up to 35 T, reveal competing antiferromagnetic exchange interactions; DFT calculations showing that the magnitudes of the coupling constants are highly dependent on both the Fe‐O‐Fe angles and Fe?O distances. The simplicity of the synthetic methodology, and the structural similarity between [Fe34], bulk iron oxides, previous FeIII–oxo cages, and polyoxometalates (POMs), hints that much larger molecular FeIII oxides can be made. 相似文献
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Mason K Chang J Garlatti E Prescimone A Yoshii S Nojiri H Schnack J Tasker PA Carretta S Brechin EK 《Chemical communications (Cambridge, England)》2011,47(21):6018-6020
The use of "double-headed" phenolic oximes produces a trigonal antiprismatic [Fe(III)(3)](2) cluster with an "internal cavity" filled with an additional Fe(3+) ion. Magnetic measurements reveal that the competition between different exchange interactions leads to a low-spin ground multiplet weakly separated in energy from a complex pattern of low-lying excited levels. 相似文献
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Carretta S Guidi T Santini P Amoretti G Pieper O Lake B van Slageren J El Hallak F Wernsdorfer W Mutka H Russina M Milios CJ Brechin EK 《Physical review letters》2008,100(15):157203
We study the spin dynamics in two variants of the high-anisotropy Mn6 nanomagnet by inelastic neutron scattering, magnetic resonance spectroscopy and magnetometry. We show that a giant-spin picture is completely inadequate for these systems and that excited S multiplets play a key role in determining the effective energy barrier for the magnetization reversal. Moreover, we demonstrate the occurrence of tunneling processes involving pair of states having different total spin. 相似文献