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1.
The K-shell X-ray fluorescence cross sections are determined experimentally for 10 elements such as Pb, Hg, Ir, W, Lu, Tm,
Dy, Tb, Gd and Nd at excitation energy of 661.6 keV associated with γ-rays of 137Cs radioisotope. The technique employed involves the measurement of total intensity of fluorescent K X-rays that follow the
photoeffect absorption of a known flux of γ-rays using a well type Nal(Tl) detector. The obtained results are compared with the available theoretical values and other
measured values. 相似文献
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Dr. Tanya K. Ronson Chandan Giri Dr. N. Kodiah Beyeh Antti Minkkinen Filip Topić Dr. Julian J. Holstein Prof. Kari Rissanen Dr. Jonathan R. Nitschke 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(10):3374-3382
Subtle differences in metal–ligand bond lengths between a series of [M4L6]4? tetrahedral cages, where M=FeII, CoII, or NiII, were observed to result in substantial differences in affinity for hydrophobic guests in water. Changing the metal ion from iron(II) to cobalt(II) or nickel(II) increases the size of the interior cavity of the cage and allows encapsulation of larger guest molecules. NMR spectroscopy was used to study the recognition properties of the iron(II) and cobalt(II) cages towards small hydrophobic guests in water, and single‐crystal X‐ray diffraction was used to study the solid‐state complexes of the iron(II) and nickel(II) cages. 相似文献
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Colm Browne Tanya K. Ronson Jonathan R. Nitschke 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(40):10877-10881
The reaction of 2,6‐diformylpyridine with diverse amines and PdII ions gave rise to a variety of metallosupramolecular species, in which the PdII ion is observed to template a tridentate bis(imino)pyridine ligand. These species included a mononuclear complex as well as [2+2] and [3+3] macrocycles. The addition of pyridine‐containing macrocyclic capping ligands allows for topological complexity to arise, thereby enabling the straightforward preparation of structures that include a [2]catenane, a [2]rotaxane, and a doubly threaded [3]rotaxane. 相似文献
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Dr. Lin Xu Dr. Dawei Zhang Dr. Tanya K. Ronson Prof. Jonathan R. Nitschke 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(19):7505-7508
The use of di(2-pyridyl)ketone in subcomponent self-assembly is introduced. When combined with a flexible triamine and zinc bis(trifluoromethanesulfonyl)imide, this ketone formed a new Zn4L4 tetrahedron 1 bearing twelve uncoordinated pyridyl units around its metal-ion vertices. The acid stability of 1 was found to be greater than that of the analogous tetrahedron 2 built from 2-formylpyridine. Intriguingly, the peripheral presence of additional pyridine rings in 1 resulted in distinct guest binding behavior from that of 2 , affecting guest scope as well as binding affinities. The different stabilities and guest affinities of capsules 1 and 2 enabled the design of systems whereby different cargoes could be moved between cages using acid and base as chemical stimuli. 相似文献
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Guest‐Induced Transformation of a Porphyrin‐Edged FeII4L6 Capsule into a CuIFeII2L4 Fullerene Receptor
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Daniel M. Wood Dr. Wenjing Meng Dr. Tanya K. Ronson Dr. Artur R. Stefankiewicz Prof. Jeremy K. M. Sanders Prof. Jonathan R. Nitschke 《Angewandte Chemie (International ed. in English)》2015,54(13):3988-3992
The combination of a bent diamino(nickel(II) porphyrin) with 2‐formylpyridine and FeII yielded an FeII4L6 cage. Upon treatment with the fullerenes C60 or C70, this cage was found to transform into a new host–guest complex incorporating three FeII centers and four porphyrin ligands, in an arrangement that is hypothesized to maximize π interactions between the porphyrin units of the host and the fullerene guest bound within its central cavity. The new complex shows coordinative unsaturation at one of the FeII centers as the result of the incommensurate metal‐to‐ligand ratio, which enabled the preparation of a heterometallic cone‐shaped CuIFeII2L4 adduct of C60 or C70. 相似文献
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Inside Back Cover: Designed Enclosure Enables Guest Binding Within the 4200 Å3 Cavity of a Self‐Assembled Cube (Angew. Chem. Int. Ed. 19/2015)
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Dr. Colm Browne William J. Ramsay Dr. Tanya K. Ronson John Medley‐Hallam Prof. Jonathan R. Nitschke 《Angewandte Chemie (International ed. in English)》2015,54(38):11122-11127
The subcomponent self‐assembly of a bent dialdehyde ligand and different cationic and anionic templates led to the formation of two new metallosupramolecular architectures: a FeII4L6 molecular rectangle was isolated following reaction of the ligand with iron(II) tetrafluoroborate, and a M5L6 trigonal bipyramidal structure was constructed from either zinc(II) tetrafluoroborate or cadmium(II) trifluoromethanesulfonate. The spatially constrained arrangement of the three equatorial metal ions in the M5L6 structures was found to induce small‐molecule transformations. Atmospheric carbon dioxide was fixed as carbonate and bound to the equatorial metal centers in both the Zn5L6 and Cd5L6 assemblies, and sulfur dioxide was hydrated and bound as the sulfite dianion in the Zn5L6 structure. Subsequent in situ oxidation of the sulfite dianion resulted in a sulfate dianion bound within the supramolecular pocket. 相似文献
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Henkelis JJ Ronson TK Harding LP Hardie MJ 《Chemical communications (Cambridge, England)》2011,47(23):6560-6562
Crystalline M(3)L(2) complexes with either single cage or triply interlocking [2]catenane chiral structures are formed the self-assembly of host-like ligands with transition metals. 相似文献