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71.
A Zinc(II) Photocage Based on a Decarboxylation Metal Ion Release Mechanism for Investigating Homeostasis and Biological Signaling 下载免费PDF全文
Dr. Prem N. Basa Sagar Antala Prof. Dr. Robert E. Dempski Prof. Dr. Shawn C. Burdette 《Angewandte Chemie (International ed. in English)》2015,54(44):13027-13031
Metal ion signaling in biology has been studied extensively with ortho‐nitrobenzyl photocages; however, the low quantum yields and other optical properties are not ideal for these applications. We describe the synthesis and characterization of NTAdeCage, the first member in a new class of Zn2+ photocages that utilizes a light‐driven decarboxylation reaction in the metal ion release mechanism. NTAdeCage binds Zn2+ with sub‐pM affinity using a modified nitrilotriacetate chelator and exhibits an almost 6 order of magnitude decrease in metal binding affinity upon uncaging. In contrast to other metal ion photocages, NTAdeCage and the corresponding Zn2+ complex undergo efficient photolysis with quantum yields approaching 30 %. The ability of NTAdeCage to mediate the uptake of 65Zn2+ by Xenopus laevis oocytes expressing hZIP4 demonstrates the viability of this photocaging strategy to execute biological assays. 相似文献
72.
Dr. Yun‐Peng Xie Dr. Jun‐Ling Jin Prof. Xing Lu Prof. Thomas C. W. Mak 《Angewandte Chemie (International ed. in English)》2015,54(50):15176-15180
The n‐butylphosphonate ligand has been employed to construct three new silver(I) thiolate compounds. Single‐crystal X‐ray analysis revealed that complexes 1 and 2 are Ag48 and Ag51 coordination chain polymers, while 3 contains a discrete Ag48 cluster, in which three different kinds of silver(I) thiolate cluster shells enclose three different phosphonate‐functionalized silver(I) cluster cores, respectively. The structures of clusters in 1 – 3 feature three three‐shell arrangements, S@Ag12@(nBuPO3)9@Ag36S23, S@Ag11@(nBuPO3)7(MoO4)2 @Ag40S27 and MoO4@Ag12@(nBuPO3)8S6 @Ag36S24, respectively. 相似文献
73.
Stepwise Halide‐Triggered Double and Triple Catenation of Self‐Assembled Coordination Cages 下载免费PDF全文
Rongmei Zhu Jens Lübben Priv.‐Doz. Dr. Birger Dittrich Prof. Dr. Guido H. Clever 《Angewandte Chemie (International ed. in English)》2015,54(9):2796-2800
A simple self‐assembled [Pd2 L 4] coordination cage consisting of four carbazole‐based ligands was found to dimerize into the interpenetrated double cage [3 X@Pd4 L 8] upon the addition of 1.5 equivalents of halide anions (X=Cl?, Br?). The halide anions serve as templates, as they are sandwiched by four PdII cations and occupy the three pockets of the entangled cage structure. The subsequent addition of larger amounts of the same halide triggers another structural conversion, now yielding a triply catenated link structure in which each PdII node is trans‐coordinated by two pyridine donors and two halide ligands. This simple system demonstrates how molecular complexity can increase upon a gradual change of the relative concentrations of reaction partners that are able to serve different structural roles. 相似文献
74.
Spherical confinement of coulombic systems inside an impenetrable box: H atom and the Hulthén potential 下载免费PDF全文
Amlan K. Roy 《International journal of quantum chemistry》2015,115(15):937-947
The generalized pseudospectral method is used to study spherical confinement in two simple Coulombic systems: (i) well celebrated and heavily studied H atom (ii) relatively less explored Hulthén potential. In both instances, arbitrary cavity size as well as low and higher states are considered. Apart from bound state eigenvalues, eigenfunctions, expectation values, quite accurate estimates of the critical cage radius for H atom for all the 55 states corresponding to , are also examined. Some of the latter are better than previously reported values. Degeneracy and energy ordering under the isotropic confinement situation are discussed as well. The method produces consistently high‐quality results for both potentials for small as well as large cavity size. For the H atom, present results are comparable to best theoretical values, while for the latter, this work gives considerably better estimates than all existing work so far. © 2014 Wiley Periodicals, Inc. 相似文献
75.
Stochastic/Controlled Symmetry Breaking of the T8‐POSS Cages toward Multifunctional Regioisomeric Nanobuilding Blocks 下载免费PDF全文
Xiao‐Man Wang Qing‐Yun Guo Shuai‐Yuan Han Jing‐Yi Wang Di Han Prof. Qiang Fu Prof. Wen‐Bin Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(43):15246-15255
Precise synthesis of nanobuilding blocks with accurately positioned functional groups presents a daunting challenge. Herein, a practical synthesis and thorough characterization of a series of T8‐polyhedral oligomeric silsesquioxane (POSS) di‐ and triadducts is reported. Upon addition of triflic acid across the double bonds in octavinylPOSS (V8T8) followed by hydrolysis, the cubic symmetry of the T8‐POSS cage (Oh) is broken into C2v (ortho‐), C2v (meta‐), and D3d (para‐) for diadducts and further to Cs (oom‐), Cs (omp‐), and C3v (mmm‐) for triadducts in a stochastic fashion. Their structures and regioconfigurations have been unambiguously demonstrated by 1H, 13C, and 29Si NMR spectroscopy, as well as MALDI‐TOF mass spectrometry. The assignment of the diadducts was further corroborated by converting each individual diadduct into triadduct(s), the structure of which is controlled by the symmetry of the precursor. Except for the C3v triadduct, they can all be prepared in synthetically useful quantities. The presence of two types of highly reactive and mutually orthogonal functional groups facilitates further modification into complex nanostructures and composite materials. These unique regioisomers provide a versatile platform for constructing giant molecules and Janus silsesquioxanes. 相似文献
76.
Discrete Rectangles,Prisms, and Heterometallic Cages from a Conjugated Cp*Rh‐Based Building Block 下载免费PDF全文
Xu‐Yu Shen Dr. Ying‐Ying Zhang Long Zhang Dr. Yue‐Jian Lin Prof. Guo‐Xin Jin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(47):16975-16981
By carefully selecting an existing synthetic strategy and suitable coordination subunits, constructing desired coordination geometries is no longer that difficult to accomplish. Herein, a new strategy to construct a series of unprecedented structures by using conjugated Cp*Rh‐based complex BN‐OTf (Cp*=η5‐C5Me5) as the building block is proposed. DFT calculations revealed extensive delocalized π bonds in the subunit. With BN‐OTf , rectangular macrocycles TN‐bpy and TN‐bpe were controllably synthesized. Single‐crystal XRD studies confirmed one‐dimensional stacking channels for the tetranuclear structure. Notably, the starting ligand imidazole‐4,5‐dicarboxylate was found to act not only as a tetradentate but also as a hexadentate ligand that can coordinate to further metal ions. Subsequently, [4 Rh+1 M] heterometallic complexes HMZ (M=Cu and Zn) were accessed by chelating borderline hard/soft Lewis acids. With TN‐Linker or HMZ , two routes resulted in the [8 Rh+2 M] heterometallic cages HMC (M=Cu and Zn) with excellent crystallinity and stability. Surprisingly, when BN‐OTf bonded to rhodium itself, triangular prisms TP‐Linker were obtained with high solubility after being linked by bipyridine linkers. Both the X‐ray structure and 1H NMR spectrum confirmed the novel isomerization of the triangular structures. All of the compounds were obtained in high yields and were fully characterized by 1H NMR spectroscopy, elemental analysis, IR spectroscopy, and in most cases single‐crystal X‐ray structure determination. 相似文献
77.
M.Sc. Ayan Dhara Dr. Florian Beuerle 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(48):17391-17396
Boron–nitrogen dative bonds provide a suitable motif for reversible, yet strong and directed interactions, leading to the highly efficient self‐assembly of small organic building blocks into supramolecular cage structures. A bipyramidal [2+3] assembly, as the first example of a supramolecular cage mediated by B?N dative bonds that exists as a discrete species in solution, is quantitatively obtained from a tribenzotriquinacene‐based trisboronate ester and 1,4‐diazabicyclo[2.2.2]octane. Thermodynamic equilibria of cage formation are investigated by isothermal titration calorimetry and fully reversible cage opening can be observed at elevated temperatures. 相似文献
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Custom-made macrocyclic receptors for fullerenes are proving a valuable alternative to achieve the affinity and selectivity required to meet challenges such as the selective extraction of higher fullerenes, their chiral resolution, or the self-assembly of functional molecular materials. In this Minireview, we highlight some of the important breakthroughs that this class of fullerene hosts has already produced. 相似文献