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1.
Branimir Raguž;Knut Wittich;Robert Glaum; 《欧洲无机化学杂志》2019,2019(11-12):1688-1696
By quenching a melt of Li4P2O7 two new, thermodynamically metastable polymorphs are obtained as biphasic mixtures. The crystal structure of one polymorph was determined from single-crystal X-ray diffraction data {Li4P2O7-trig*: colorless, trigonal, P3212 (no. 153), Z = 3, a = 5.1699(2) Å, c = 18.9722(8) Å, 60 parameters, R1 = 0.018, wR2 = 0.051, 1265 unique reflections with Fo > 4σ(Fo)}. For the second polymorph a structure model was derived, using direct space methods followed by Rietveld refinement {Li4P2O7-pseudomono*: P1, a = 7.88468(5) Å, b = 10.30394(6) Å, c = 7.54581(4) Å, α = 89.8142(6)°, β = 115.26(2)°, γ = 90.2015(5)°, RI = 7.62}. 31P-MAS-NMR measurements show δiso = –2.9 ppm for Li4P2O7-pseudomono* and δiso = –6.6 ppm for the trigonal polymorph. Substitution of about 10 % lithium by copper(I) is possible in the trigonal as well as in the long known triclinic polymorph as is evidenced by the results of SXRD, XRPD, and 31P-MAS-NMR measurements. 相似文献
2.
Dennis P. Curran 《Angewandte Chemie (International ed. in English)》1998,37(9):1174-1196
A dirty word in synthesis: separation! The normally unavoidable separation at the end of each reaction finds no friends among synthetic chemists and is often regarded as a technical procedure. However, the need to quickly and cheaply produce pure products is driving the development of new separation and purification techniques. Astonishingly, the modern concepts and techniques for coupling synthesis and separation are rooted in workup procedures that are as old as the art of synthesis itself. 相似文献
3.
An environment dependent effective potential was employed in the structure prediction for the not-yet-synthesised compound Ca3SiBr2. Using a combination of global and local optimisation methods, nine local minima on the potential energy hypersurface with low energy values were determined. Subsequently, the energies of the corresponding configurations were recalculated using an ab-initio method. In order to estimate the stability of these structures, the regions of the energy landscape close to these minima were investigated with the threshold-algorithm. Combining all these results suggests that the title compound should be capable of existence and most probably crystallize in a NaCl-superstructure. 相似文献
4.
James B. Hendrickson 《Angewandte Chemie (International ed. in English)》1990,29(11):1286-1295
The computer affords four areas of interest to synthetic chemists: (1) storage and retrieval of information; (2) complex calculations of shape and reaction dynamics; (3) artificial intelligence (AI) to solve synthetic and analytical problems; (4) overall direction of multiple laboratory experiments. Our work began 30 years ago initiating molecular geometry calculations to match experimental results. The explosive growth of computer power since will be illustrated. Synthesis design (as AI) requires an efficient protocol to search huge trees. The SYNGEN program is based on simplification and systematization, first of skeletal dissection, then of structure and reaction characterization, for generation of optimal synthesis routes. The program will be be described and its future development outlined. Finally, a perspective on the future of all four areas will be sketched, noting the necessary attendant growth in systematic use by chemists and in sympathetic interfaces by software designers. 相似文献
5.
Snke Mhr Hanskarl Mller-Buschbaum 《Angewandte Chemie (International ed. in English)》1995,34(6):634-640
The establishment of solid state chemistry as an independent field, which also has had a stimulating effect on material sciences, is a consequence of the experimental skill of chemists. The development of new methods led to an abundance of new compounds, the characteristic properties of which are linked with the solid state. The reaction temperature plays an important role in the synthesis of solid compounds; therefore, it is not surprising that a large number of the newly developed experimental techniques involve methods which can produce high temperatures on the openended temperature scale. Since the development of the CO2 laser, the solidstate chemist has an excellent heat source available, and with the power available today the range of high temperatures possible has been extended considerably. A way is now open for producing metastable, “entropy-supported” high-temperature compounds and substances with anomalous oxidation states and with macroscopic defects. 相似文献
6.
G. Bergerhoff 《无机化学与普通化学杂志》2001,627(9):2075-2080
All known crystal structures with the general formula a1b4c6, collected in the database SICS, are systematically investigated for isotypism by δ‐matrices, for homeotypism by structural charateristics of minor constituents and group‐subgroup relations, and for interstitial types by relations between Wyckoff sequences. The procedure is designed to be implemented into the database retrieval system. 相似文献
7.
Art Kruithof;Jos R. Mulder;J. M. Ruiz;Elwin Janssen;M. Mooijman;Eelco Ruijter;Célia Fonseca Guerra;F. Matthias Bickelhaupt;Romano V. A. Orru; 《European journal of organic chemistry》2018,2018(1):104-112
Predicting reactivity in multicomponent reactions (MCRs) is extremely difficult. These reactions proceed by multiple pathways and are inherently associated with a potentially large variation of reactants and functional groups. To date, theoretical chemistry has been used in hindsight to verify experimental observations. However, its use in the early stages of the development of a (multicomponent) reaction process can prevent laborious and time-consuming optimization studies by pinpointing the most relevant parameter(s) in the reactivity, thus focusing experimental efforts. Herein, we discuss a study that truly integrates theoretical and synthetic chemistry to unravel in full detail the complex and intricate reaction characteristics of the novel versatile MCR of α-acidic iso(thio)cyanates, amines and aldehydes to access densely functionalized imidazoline-2-(thi)ones. 相似文献
8.
Erik Schumann Dr. Erica Brendler Dr. Uwe Böhme Prof. Dr. Florian Mertens 《欧洲无机化学杂志》2023,26(2):e202200568
Despite decades of research on various carbamates and their important applications, only one aluminum N,N-dialkylcarbamate (ADC) with an aluminum:carbamate ratio of 1 : 3 has been structurally described and comprehensively studied so far, namely tris(diisopropyl)carbamate. The reasons for this situation include problems with the used synthetic routes. The process of CO2 insertion into Al−N bonds of tris(dialkylamido)alanes resolved these difficulties. Using this advantageous synthetic route, the dimethyl and diethyl, as well as the pyrrolidino, piperidino, and N-methylpiperazino derivatives were now successfully prepared. These ADCs were investigated by solid-state NMR spectroscopy, where line-shape analyses of the 27Al NMR spectra allowed conclusions with respect to the determination of the quadrupole coupling parameters. Furthermore, data of an intermediate during the CO2 insertion into tris(diisopropylamido)alane were obtained by in-situ IR spectroscopy, which were complemented by NMR measurements of samples periodically taken during the reaction. Partial hydrolysis of tris(pyrrolidino)carbamate revealed a complex Al3(μ3-O) cluster structure, which was elucidated by single crystal X-ray diffraction. 相似文献
9.
Lisa Gamperl;Georg Krach;Peter J. Schmidt;Wolfgang Schnick; 《欧洲无机化学杂志》2019,2019(47):4985-4993
The oxonitridosilicates RE6–xCa1.5xSi11N20O (RE = Yb, Lu; x ≈ 2.2) were synthesized starting from REF3, CaH2, and ”Si(NH)2” in a radiofrequency furnace at 1600 or 1400 °C, respectively. The crystal structure was solved and refined from single-crystal X-ray diffraction data of dark red Yb6–xCa1.5xSi11N20O crystals in the trigonal space group P31c (no. 159) with a = 9.8281(10), c = 10.5968(13) Å and Z = 2. The structure represents a filled variant of the Er6Si11N20O structure type, in which the charge difference caused by substitution of trivalent Yb3+ with bivalent Ca2+ is balanced by occupation of an additional third cation site. Synthesis of Lu6–xCa1.5xSi11N20O:Ce3+ resulted in a yellow powder with yellow luminescence. Powder X-ray data were analyzed by Rietveld refinement based on the crystal data obtained from Yb6–xCa1.5xSi11N20O. The Ce3+ doped compound exhibits a broad emission (fwhm ≈ 168 nm/≈ 5100 cm–1) with a maximum at λem ≈ 565 nm. The emission extends more in the red spectral range compared to YAG:Ce3+, thus making it an interesting phosphor for warm-white single phosphor converted light-emitting diodes (1pcLED) with an improved color rendering index. 相似文献
10.
Five new cyclophane host molecules (corrals) are prepared by linking together two α,α′-di(4-hydroxyphenyl)-1,4-diisopropylbenzene or α,α′-di(3,5-dimethyl-4-hydroxyphenyl)-1,4-diisopropylbenzene units with two permethylene spacers. Three small cyclophane hosts (boxes) are synthesized by cyclization of α,α′-di(4-hydroxyphenyl)-1,4-diisopropylbenzene with di(bromomethyl)benzene compounds. Solid-state structures of one corral and one box are reported. 相似文献
11.
Solid-state mechanochemical reactions of iron(II) chloride with cyclopentadienides of alkaline metals or thallium, which lead to the formation of ferrocene, were studied. The dependence of the yield of the product on the parameters of mechanical loading for the reaction with cyclopentadienylthallium was determined. 相似文献
12.
Niklas Cordes;Thomas Bräuniger;Wolfgang Schnick; 《欧洲无机化学杂志》2018,2018(46):5019-5026
Alkaline earth oxonitride perovskites EAMO2N (EA = Sr, Ba; M = Nb, Ta) were synthesized by the ammonothermal method at temperatures of 900 K and maximum pressures of up to 300 MPa in custom-built autoclaves starting from Nb or Ta and Sr or Ba metals. The reactions were performed under ammonobasic conditions using NaN3 and NaOH as mineralizers. Powder X-ray diffraction and Rietveld refinement were used to determine the crystal structures. The elemental composition and morphology of the obtained products were investigated by scanning electron microscopy and energy-dispersive X-ray spectroscopy. Crystals of 1–10 µm size were obtained. Optical band gap values were determined from UV/Vis measurements applying the Kubelka–Munk function with the Tauc method (Eg = 1.9 - 2.1 eV). In addition to that, ANb/Ta(O,N)3 with A = Ca, Sr, Ba, La were synthesized by ammonolysis reactions of the respective ternary oxide precursors. The products were investigated with 14N solid-state (MAS) NMR spectroscopy, all showing a single resonance at about 270 ppm. 相似文献
13.
Bernd Sauerbrei Volker Jungmann Herbert Waldmann 《Angewandte Chemie (International ed. in English)》1998,37(8):1143-1146
Lipases and esterases can be used to fragment the 4-acetyloxybenzyloxy group used as a linker for organic synthesis on solid supports. (A support-bound compound is shown on the right; the enzyme-labile bond is marked with an arrow.) This enzyme-initiated fragmentation proceeds under very mild conditions (pH 6–7, room temperature), and the compounds of interest (amines, alcohols, carboxylic acids; X=NH, O, CR2) constructed by combinatorial chemistry can be released with complete selectivity. 相似文献
14.
High-temperature reactions have always been a fascinating although difficult field of experimentation for the chemist. In the case of solid-state reactions the problems with apparatus increase exponentially with rising temperature, so that especially in this area of inorganic chemistry the modern techniques of producing high temperatures—from the solar furnace to the high-power CO2 laser—have yielded new and interesting possibilities, particularly in the field of metastable high-temperature compounds. 相似文献
15.
16.
Christiane Stoll;Markus Seibald;Dominik Baumann;Hubert Huppertz; 《欧洲无机化学杂志》2019,2019(29):3383-3388
K3MoOF7:Mn4+ was synthesized through a facile two-step solid-state synthesis route without using HF. The first step was carried out in copper ampules, which were shut by welding, followed by the second step, a ball milling experiment. The sample was characterized by single-crystal and powder X-ray diffraction, EDX, and luminescence spectroscopy. K3MoOF7 crystallizes in the triclinic space group P1 (no. 2). It features [MoOF5]– units as a main structural motif. At room temperature, seven emission lines are noticeable. The maximum emission line is located at λmax = 627 nm. CIE1931 coordinates could be determined to 0.690(1) and 0.310(1) for x and y, respectively. A luminous efficacy of radiation (LER) of 218 lm Wopt–1 was achieved. Furthermore, temperature dependent luminescence measurements in the range of 25 °C to 100 °C were conducted. 相似文献
17.
18.
Inorganic solid electrolytes play a critical role in solid-state lithium batteries achieving high safety levels and high energy densities. The synthetic approaches to solid electrolytes are important for both fundamental research and practical applications. Li1+xAlxTi2−x(PO4)3 (LATP) and Li1+xAlxGe2−x(PO4)3 (LAGP) are two representative solid electrolytes with a sodium superionic conductor (NaSICON) structure. Herein, LATP and LAGP solid electrolytes are reviewed from the synthesis perspective, and correlated with their structure and conductive properties, as well as their electrochemical applications in batteries. First, the solid- and liquid-based synthetic methods to LATP and LAGP solid electrolytes and the key influencing factors are described. Second, the crystal structures and phase purities obtained from different synthetic approaches are introduced. Third, the conductive mechanisms, composition effects, and synthetic effects on the conductivities of LATP and LAGP solid electrolytes are compared. Fourth, the electrochemical applications of these two solid electrolytes in full batteries are discussed, including roles as solid electrolytes, composite components in electrodes, and surface coatings on electrodes. In the last section, a brief outlook is provided on the future development of NaSICON-type solid electrolytes for all-solid-state batteries. 相似文献
19.
Gunnar Jeschke Wilfried Hoffbauer Martin Jansen 《Chemistry (Weinheim an der Bergstrasse, Germany)》1998,4(9):1755-1761
Unexpected splittings in solid-state MAS-NMR spectra can indicate high rather than low local symmetry. A quantitative analysis of the resulting lineshapes provides information about geometry from a different range of space and time averaging than that of X-ray crystallography, as is demonstrated here for tetraphosphorus decaoxide (spectra on the right). 相似文献
20.
Chemoinformatics: a new field with a long tradition 总被引:2,自引:0,他引:2
Gasteiger J 《Analytical and bioanalytical chemistry》2006,384(1):57-64
Chemoinformatics is the application of informatics methods to solve chemical problems. Although this term was introduced only
a few years ago, this field has a long history with its roots going back more than 40 years. Work on chemical structure representation
and searching, quantitative structure–activity relationships, chemometrics, molecular modeling as well as computer-assisted
structure elucidation and synthesis design was initiated in the 1960s. These different origins have now merged into a discipline
of its own that is in full bloom. All areas of chemistry from analytical chemistry to drug design can benefit from chemoinformatics
methods. And there are still many challenging chemical problems waiting for solutions through the further development of chemoinformatics. 相似文献