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561.
Synthesis and Crystal Structure of Terbium(III) meta‐Oxoborate Tb(BO2)3 (≡ TbB3O6) The terbium meta‐oxoborate Tb(BO2)3 (≡ TbB3O6) is obtained as single crystals by the reaction of terbium, Tb4O7 and TbCl3 with an excess of B2O3 in gastight sealed platinum ampoules at 950 °C after three weeks. The compound appears to be air‐ and water‐resistant and crystallizes as long, thin, colourless needles which tend to growth‐twinning due to their marked fibrous habit. The crystal structure of Tb(BO2)3 (orthorhombic, Pnma; a = 1598.97(9), b = 741.39(4), c = 1229.58(7) pm; Z = 16) contains strongly corrugated oxoborate layers {(BO2)‐} built of vertex‐linked [BO4]5‐ tetrahedra (d(B‐O) = 143 ‐ 154 pm, ?(O‐B‐O) = 102‐115°) which spread out parallel (100). The four crystallographically different Tb3+ cations all exhibit coordination numbers of eight towards the oxygen atoms (d(Tb‐O) = 228‐287 pm). The corresponding metal cation polyhedra [TbO8]13+ too convene to layers (composition: {(Tb2O11)16‐}) which are likewise oriented parallel to the (100) plane. 相似文献
562.
S. Svane J. Kuntsche F. Steiniger A. Eich L. Duelund V. McKee 《Supramolecular chemistry》2013,25(10):642-653
A dicopper(II) complex can be covalently linked to palmitate/palmitoyl-oleoyl-phosphatidylcholine (PA/POPC) liposomes using the following one-pot strategy: preformed [Cu2(bpbp)(PA)](ClO4)2 (bpbp? = 2,6-bis((N,N′-bis(2-picolyl)amino)methyl)-4-tertbutylphenolato) was incorporated into POPC liposomes with a loading of up to 10 mol%. Despite its shape and charge, the decoration of PA/POPC liposomes with {Cu2(bpbp)}3+ did not disrupt the liposome structure; however, the mean liposome diameter increased from about 130 nm (0 mol% dicopper complex) to about 150 nm (10 mol% dicopper complex). Single-crystal X-ray structures furnish ‘snapshots’ of the pH-dependent solution state derivatives of {Cu2(bpbp)}3+, and model the structure of the [Cu2(bpbp)(PA)]2+ head group at the surface of the liposomes. An impressive plasticity in the intramolecular non-bonded Cu….Cu distance for these ions, ranging from 3 to 4 Å, in [Cu2(bpbp)OH]2+, [Cu2(bpbp)(OAc)(H2O)]2+ and [Cu2(bpbp)(H2O)2]3+ allows for their utility as labile reagents in water. Remarkably, the flexible dicopper site is selective for a single carboxylate ligand, so that [Cu2(bpbp)(PA)]2+ is favoured even in the presence of other chemically similar oxoanions, such as CO32 ? , HCO3? , NO3? , ClO4? , ReO4? and CF3SO3? . 相似文献
563.
Tanja Stojadinović 《Czechoslovak Mathematical Journal》2013,63(1):107-113
A multiplicative functional on a graded connected Hopf algebra is called the character. Every character decomposes uniquely as a product of an even character and an odd character. We apply the character theory of combinatorial Hopf algebras to the Hopf algebra of simple graphs. We derive explicit formulas for the canonical characters on simple graphs in terms of coefficients of the chromatic symmetric function of a graph and of canonical characters on quasi-symmetric functions. These formulas and properties of characters are used to derive some interesting numerical identities relating multinomial and central binomial coefficients. 相似文献
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565.
Bo Zhang Ansila Mathoor Prof. Tanja Junkers 《Angewandte Chemie (International ed. in English)》2023,62(38):e202308838
An automated high throughput multidimensional reaction screening platform based on an inline Fourier-transform infrared spectroscopy is presented. By combining flow chemistry, machine automation and inline analysis, the platform is able to screen reactions in multidimensions (residence time, monomer concentration, degree of polymerization, reaction temperature and monomer conversion) rapidly and efficiently way. Kinetic data libraries associated with high data precision (absolute error <4 %), high reproducibility and high data density are built with ease from the platform. To test the method, we screened the reversible addition-fragmentation chain transfer polymerization of methyl acrylate in unmatched detail, and the ring opening metathesis polymerization of methyl-5-norbornene-2-carboxylate. The method we introduce is a key step in providing “big data” for data driven research in the future, and already at present allows for precise prediction of reaction outcomes within the high-dimensional chemical parameter space that is screened. 相似文献
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568.
Franziska Karcher Matthias Uhl Tanja Geng Timo Jacob Rolf Schuster 《Angewandte Chemie (International ed. in English)》2023,62(22):e202301253
The formation of an appropriate solid electrolyte interphase (SEI) at the anode of a sodium battery is crucially dependent on the electrochemical stability of solvent and electrolyte at the redox potential of Na/Na+ in the respective system. In order to determine entropic contributions to the relative stability of the electrolyte solution, we measure the reaction entropy of Na metal deposition for diglyme (DG) and propylene carbonate (PC) based electrolyte solutions by electrochemical microcalorimetry at single electrodes. We found a large positive reaction entropy for Na+ deposition in DG of ΔR 234 J mol−1 K−1 (c.f.: ΔR 83 J mol−1 K−1), which signals substantial entropic destabilization of Na+ in DG by about 0.73 eV, thus increasing the stability of solvent and electrolyte relative to Na+ reduction. We attribute this strong entropic destabilization to a highly negative solvation entropy of Na+, due to the low dielectric constant and high freezing entropy of DG. 相似文献
569.
Markus Klapper Yong-Jun Jang Kirsten Bieber Tanja Nemnich Nikolay Nenov Klaus Müllen 《Macromolecular Symposia》2004,213(1):131-146
Nano-sized latex particles as organic supports for metallocenes applied in olefin polymerizations are introduced. The particles are functionalized with nucleophilic surfaces such as polyethylenoxide (PEO), polypropyleneoxide (PPO) or pyridine units allowing an immobilization of the metallocene catalysts via a non-covalent immobilization process. The latices are obtained by emulsion or miniemulsion polymerization with styrene, divinylbenzene as the crosslinker, and either PEO or PPO functionalized styrene or 4-vinylpyridine for surface functionalization. The supported catalysts, e.g. [Me2Si(2MeBenzInd)2ZrCl2/MAO] on PPO containing latices or Cp2ZrMe2/([Ph3C][B(C6F5)4]) on pyridine functionalized materials were tested in ethylene polymerizations. Remarkably, high activities and excellent product morphologies were obtained. The influence of the degree of surface functionalization on activity and productivity was investigated. Furthermore, the fragmentation of the catalyst was studied by electron microscopy using bismuth-labeled latex particles or by fluorescence and confocal fluorescence microscopy using dye-labeled supports. Finally, a self-immobilizing catalyst/monomer system is presented. It is demonstrated that by using PEO-functionalized olefins, the metallocenes were immobilized on the monomers. Subjecting these mixtures to an ethylene copolymerization, again high activities and productivities as well as polyolefin beads with high bulk densities are observed, indicating that an extra supporting process for controlling the product size and shape of the polyolefins is not necessary for these monomers. 相似文献
570.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献