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171.
Eswaran Chinnaraja Rajendran Arunachalam Renjith S. Pillai Anssi Peuronen Kari Rissanen Palani S. Subramanian 《应用有机金属化学》2020,34(8):e5666
Synthesis of binuclear Cu(II) terminally closed [ 2+2 ]- double-stranded helicate-like macrocycles 1, 1′ , 1″ , 2 , 2′ , 2″ and 2+4- μ4-oxo tetranuclear open frame complexes 3 , 3′ , 3″ , 4 , 4′ , 4″ are established. Adapting one-pot self-assembly technique from simple three components systems: 1,1′-binaphthyl-2,2′-diamine, 4-methyl-2,6-diformyl phenol and cupric salts, the helicate-like [ 2+2 ]- macrocyclic complexes 1–1″, 2–2″ and 2+4- μ4-oxo tetranuclear complexes 3–3″ , 4–4″ were obtained by appropriately altering the reaction condition such as temperature and subcomponent ratio. Density Functional Theory (DFT) calculations were carried out for understanding the structural geometries, intermediates involved in the diverse formation of [ 2+2 ] and 2+4 frameworks. The single crystal X-ray structures obtained for 1′ , 2 and 3 confirms the self-assembly process in line with DFT. This detailed analysis tempted us to derive a plausible mechanism for this long standing challenge in the synthesis of such macrocycles using 1,1′-binaphthyl-2,2′-diamine (BNDA) and aromatic aldehyde. The chiroptical properties of enantiopure complexes and their catalytic applications in asymmetric oxidative coupling of 2-naphthol to chiral 1,1’-Bi-2-naphthol (BINOL) achieved in good yield and ee were discussed. 相似文献
172.
A. Carel N. Kwamen Marcel Schlottmann Dr. David Van Craen Dr. Elisabeth Isaak Julia Baums Li Shen Ali Massomi Dr. Christoph Räuber Benjamin P. Joseph Prof. Dr. Gerhard Raabe Dr. Christian Göb Prof. Dr. Iris M. Oppel Dr. Rakesh Puttreddy Dr. Jas S. Ward Prof. Dr. Kari Rissanen Dr. Roland Fröhlich Prof. Dr. Markus Albrecht 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(6):1396-1405
The dissociation of hierarchically formed dimeric triple lithium bridged triscatecholate titanium(IV) helicates with hydrocarbyl esters as side groups is systematically investigated in DMSO. Primary alkyl, alkenyl, alkynyl as well as benzyl esters are studied in order to minimize steric effects close to the helicate core. The 1H NMR dimerization constants for the monomer–dimer equilibrium show some solvent dependent influence of the side chains on the dimer stability. In the dimer, the ability of the hydrocarbyl ester groups to aggregate minimizes their contacts with the solvent molecules. Due to this, most solvophobic alkyl groups show the highest dimerization tendency followed by alkenyls, alkynyls and finally benzyls. Furthermore, trends within the different groups of compounds can be observed. For example, the dimer is destabilized by internal double or triple bonds due to π–π repulsion. A strong indication for solvent supported London dispersion interaction between the ester side groups is found by observation of an even/odd alternation of dimerization constants within the series of n-alkyls, n-Ω-alkenyls or n-Ω-alkynyls. This corresponds to the interaction of the parent hydrocarbons, as documented by an even/odd melting point alternation. 相似文献
173.
Conversion elecron spectroscopy has been an important part of the nuclear spectrocopy research at the Department of Physics of the University of Jyväskylä since the commissioning of the first cyclotron in the mid 1970s. At the IGISOL facility a specialiced conversion electron spectrometer ELLI was developed in the late 1980s. The first results with ELLI were obtained using the beams from the old MC-20 cyclotron to study newly discovered isotopes of refractory fission products. In the present K130 cyclotron laboratory ELLI has been utilized in many decay-spectroscopy experiments both neutron-deficient and neutron-rich side of the valley of stability. In the early 2000s the new JYFLTRAP ion trap system overthrew ELLI from its permanent place in the IGISOL beamline. Conversion electron spectroscopy has continued with the new Penning trap that has been used in in-trap electron spectroscopy tests and post-trap electron spectroscopy is foreseen. 相似文献
174.
175.
176.
The inequalities su At su Am ≥ su Ap su Aq and At+ su Am≥ su Ap+ su Aq are studied and generalized. Here su A denotes the sum of elements of the square matrix A. 相似文献
177.
Jorma Tarhio 《BIT Numerical Mathematics》1990,30(3):437-449
Evaluation of inherited attributes is a problem in conjunction with LR parsing, because the derivation tree is incomplete during parsing. An evaluation scheme for inherited attributes is presented based on a restricted grammar class, uncle-attributed grammars. A transformation to the uncle-attributed form is described for L-attributed grammars. 相似文献
178.
A comparative TG and DTG study of the preparation and thermal stability of selected rare earth oxycarbonates, (REO)2CO3 (RE = La and Gd), shows that the ease of formation as well as the stability of these compounds decreases strongly with increasing atomic number of the host cation. According to X-ray powder diffraction analyses, the RE oxycarbonates obtained as decomposition products of acetate and carbonate hydrates belong to the tetragonal IA-type. UV- and dye laser-excited luminescence studies of Eu3+-doped (LaO)2CO3 and (GdO)2CO3 reveal the presence of two different sites for the host cation. One of the sites resembles closely that prevailing in the tetragonal RE oxysalts, i.e. oxyhalides, oxysulphates, oxymolybdates and oxynitrates. A crystal field analysis carried out on the 7F1 and 7F2 level schemes according to a C2v site symmetry confirms this hypothesis. 相似文献
179.
A fluid queue receiving its input from the output of a precedingM/M/1 queue is considered. The input can be characterized as a Markov modulated rate process and the well known spectral decomposition technique can be applied. The novel features in this system relate to the nature of the spectrum, which is shown to be composed of a continuous part and one or two discrete points depending on whether the load of the fluid queue is less or greater than the output to input rate ratio. Explicit expressions of the generalized eigenvectors are given in terms of Chebyshev polynomials of the second kind, and the resolution of unity is determined. The solution for the buffer content distribution is obtained as a simple integral expression. Numerical examples are given. 相似文献
180.
It is demonstrated that in many situations the sum of elements and the trace of a matrix behave similarly. 相似文献