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101.
Gerhard Simchen Günther Entenmann 《Angewandte Chemie (International ed. in English)》1973,12(2):119-126
Five-membered, six-membered, and seven-membered aza-, diaza-, and thiazaheterocycles can be prepared by cyclization of. ω-cyano carboxylic acid halides in the presence of hydrogen halides in aprotic solvents. Nitrile-hydrogen halide adducts occur as intermediates in this novel heterocycle synthesis of wide application. The acylating cyclizations of nitriles in protonic media, which proceed via imidic esters or amides, are not discussed. 相似文献
102.
Rotational barriers of the NH2 group in thiourea and benzylurea in solution become slightly larger in the presence of anionic hydrogen‐bond acceptors. The interactions between the N? H bond and different anions were investigated in acetonitrile solution using 1H{14N} variable‐temperature NMR. Line‐shape analyses of the spectra show a weakly anion‐dependent increase in ΔG? of rotation, with benzoate having the strongest effect and iodide the weakest. Hydrogen‐bonding acidities of benzylurea and thiourea were also measured on the Abraham solute hydrogen‐bond acidity scale by proton NMR. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
103.
Hiyoshizo Kotsuki Yoshikatsu Ichikawa Mitsuhiro Iwasaki Masanori Kataoka Hitoshi Nishizawa 《高压研究》2013,33(1-3):107-118
Abstract A variety of cyclic and acyclic ethers are efficiently reacted with acyl chlorides or acyl bromides to afford the ether-cleaved compounds of ω-chloro-or ω-bromoesters under high pressure conditions. The reactivity of ethers is found to be roughly depend on the basicity of the ether oxygen atom. 相似文献
104.
Abstract A brief survey of our studies of free and self-trapped excitons (FE and STE) in alkali halide crystals under hydrostatic pressure up to 12.5 kbar at 4.2–140 K is presented. Main attention is paid to the following effects observed: (1) the strong coupling of three energy levels of FE in CsI revealing itself as an exciton analog of pressure-scanned Fermi resonance; (2) emergence of a new emission band of STE in CsI under pressure; (3) a large pressure shift of the thermal quenching curve for STE emission in NaCl. 相似文献
105.
Aliovalent Rh and Ir cations have been frequently used to influence the photographic properties of silver halide emulsions. The doping introduces several types of related defects with distinct trapping and recombination properties. EPR and ENDOR are, in principle, ideally suited for the determination of the microscopic structure of the individual centres but it will be demonstrated that well-chosen, sometimes sophisticated multi-frequency experiments are necessary in order to (partially) reach this goal. Model studies on single crystals of AgCl and NaCl also appeared indispensable for the unravelling of the spectra.In the review of Rh-centres in NaCl and AgCl special attention is paid to methods that allow to detect cation vacancies near Rh2? complexes. An alternative explanation for the high temperature behaviour of the [RhCl6]4? complexes in AgCl is presented. 相似文献
106.
Increasing the stability of perovskite solar cells is one of the most important tasks in the photovoltaic industry. Thus, the structural, energetic, and electronic properties of pure CH3NH3PbI3 and fully doped compounds (CH3NH3PbBr3 and CH3NH3PbCl3) in cubic and tetragonal phases were investigated using density functional theory calculations. We also considered the effects of mixed halide perovskites CH3NH3PbI2X (where X = Br and Cl) and compared their properties with CH3NH3PbI3. The DFT results indicate that the phase transformation from tetragonal to cubic phase decreases the band gap. The calculated results show that the X‐site ion plays a vital role in the geometrical stability and electronic levels. An increase in the band gap and a reduction in the lattice constants are more apparent in CH3NH3PbI2X compounds (I > Br > Cl). 相似文献
107.
太阳能驱动光催化反应降解污染物、制备化学燃料或其他高附加值产品是绿色化学和可再生能源研究的重要方向.近年来,在传统的金属氧化物半导体材料之外,金属卤化物钙钛矿类化合物凭借其优异的光电特性也被逐步应用于高效光催化反应中.这篇文章综述了以铅卤钙钛矿为主的金属卤化物钙钛矿材料近年来在光催化领域的研究进展,总结了金属卤化物钙钛矿材料在光(电)催化产氢、CO2还原反应和有机物高附加值转化反应中的应用与反应机制及其关键挑战,最后展望了高效稳定的金属卤化物钙钛矿光催化剂的发展方向和前景. 相似文献
108.
The long-term stability remains one of the main challenges for the commercialization of the rapidly developing hybrid organic-inorganic perovskite solar cells. Herein, we investigate the electronic and optical properties of the recently reported hybrid halide perovskite (CH2)2NH2PbI3 (AZPbI3), which exhibits a much better stability than the popular halide perovskites CH3NH3PbI3 and HC(NH2)2PbI3, by using density functional theory (DFT). We find that AZPbI3 possesses a band gap of 1.31 eV, ideal for single-junction solar cells, and its optical absorption is comparable with those of the popular CH3NH3PbI3 and HC(NH2)2PbI3 materials in the whole visible-light region. In addition, the conductivity of AZPbI3 can be tuned from efficient p-type to n-type, depending on the growth conditions. Besides, the charge-carrier mobilities and lifetimes are unlikely hampered by deep transition energy levels, which have higher formation energies in AZPbI3 according to our calculations. Overall, we suggest that the perovskite AZPbI3 is an excellent candidate as a stable high-performance photovoltaic absorber material. 相似文献
109.
Ab initio calculations have been performed to investigate some of the spectroscopic properties, like geometry, frequency, electron affinity, ionization potential and finally adiabatic bond dissociation energies (BDEs) of lead monohalides, lead dihalides and their ions viz. PbX, PbX±, PbX2, (X ?= ?F, Cl, Br, I) in their ground state at the QCISD(T)//MP2 level of theory using correlation consistent basis sets. For the validation of MP2 optimized geometry and frequency, we further obtained geometry and frequency of all the neutral and ionic systems using QCISD(T) method with the same basis sets. The BDEs of PbX2 molecules are calculated using the BDEs of ions and taking ionization potential and electron affinity of various systems. The calculated values are found in good agreement with the available data. Most of the data for ionic systems are reported first time in literature. 相似文献
110.
Braulio Aranda Sergio A. Moya Andres Vega Gonzalo Valdebenito Sofia Ramirez‐Lopez Pedro Aguirre 《应用有机金属化学》2019,33(4)
Aminocarbonylation of aryl halides, homogeneously catalysed by palladium, is an efficient method that can be employed for obtaining amides for pharmaceutical and synthetic applications. In this work, palladium (II) complexes containing P^N ligands were studied as catalysts in the aminocarbonylation of iodobenzene in the presence of diethylamine. Two types of systems were used: a palladium (II) complex formed in situ; and one prepared prior to the catalytic reaction. In general, the palladium complexes studied achieved high conversions in an average reaction time of less than 2 hr, which is less than that for the standard system (Pd (II)/PPh3) used. The pre‐synthesized complexes were faster than their in situ counterparts, as the latter require an induction time to form the Pd/P^N species. The structure and electronic properties of the ligand P^N can influence both the activity and the selectivity of the reaction, stabilizing the acyl‐palladium intermediates formed in a better manner. 相似文献