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41.
Newly established in 2018, the UK Research and Innovation (UKRI) strengthens the strategic coordination of the UK research and innovation system by bringing together seven Research Councils, Research England, and Innovate UK. Through its nine organizations, UKRI funds multidisciplinary and interdisciplinary research in a number of priority areas. It also runs the Strategic Priorities Fund to support multidisciplinary and interdisciplinary research in strategic areas identified by government policies as well as the Global Challenges Research Fund to promote challenge-led interdisciplinary research needed by developing countries. The UKRI makes significant efforts to engage stakeholders in the development, design, and implementation of multidisciplinary and interdisciplinary programs. It has also developed a range of mechanisms to improve the evaluation of multidisciplinary and interdisciplinary projects. Chinese science and innovation funding agencies could draw upon the UKRI experience from four aspects to advance interdisciplinary research in China. 相似文献
42.
Importing intramolecular hydrogen bond in phosphorescent transition metal complexes has been considered one of the excellent approaches to improve the electroluminescence performance of organic light-emitting diodes in real applications. However, the relationships between such H-bond structure and phosphorescent properties have not been theoretically revealed yet. In this study, two types of intramolecular hydrogen bonds are introduced into the two classes of traditional materials, that is, Pt(II) and Ir(III) complexes ( 1a and 2a ) to completely elucidate their influence on the structures and properties by comparing with the original phosphors ( 1b and 2b ) using density functional theory/time-dependent density functional theory for the first time. A comprehensive analysis of the geometric structures, molecular orbitals, and luminescence properties (including phosphorescence emission wavelengths and radiative and nonradiative decay processes) has been carried out. Our theoretical model highlights that complexes 1a and 2a embedded with H-bonds significantly promote the phosphorescence emission band blue-shifted and restrict molecular deformations compared with the corresponding 1b and 2b , which can provide helpful guidance to regulate and design several aspects of highly efficient blue phosphorescent emitters. 相似文献
43.
Zeinab Ahmadvand Mehdi Bayat Mohammad Ali Zolfigol 《Journal of computational chemistry》2020,41(26):C1-C1
Pd-PEPPSI type complexes are widely used as precatalyst in a variety of organic reactions, including the Negishi, Kumada and Suzuki-Miyaura cross-coupling reactions. The aim of this research is to determine potential proposed reaction pathways 1, 2, or 2′ (See Schemes 1 and S1–S4 ) for Pd-PEPPSI precatalyst activation in the presence of ethylene glycol as a solvent also in the gas phase at Cam-B3LYP-D3 method nominated among eight DFT methods examined. There is also investigation into the impact of promoter bases (NaOEt, NaOiPr, NaOtBu) on precatalyst activation of Pd-PEPPSI. Eventually, the most favorable proposed reaction pathway and promoter base for reducing Pd(II) to Pd(0) are predicted computationally. Notably, our findings are consistent with the organ Pd-PEPPSI type complexes that offer increased catalytic activity and provide basic information in the presence of solvents designing the monoligated Pd(0)-solvent. 相似文献
44.
The elementometalation process is a fundamental chemical step in several catalytic cycles. In this work, density functional theory computations have elucidated the detailed elementometalation mechanism of activated alkyne RCCR(RCO2Me) by Cp2TaH3 and rationalized the selectivity in experimental findings. The calculated results show that in the formation process of (E)-olefin monohydride((E)-Pro), the Gibbs free energy barrier is low and the entire reaction is spontaneous and exothermic; thus, (E)-Pro can be formed easily. The formation of (Z)-η2-olefin monohydride complex ((Z)-Pro) is difficult due to its high Gibbs free energy barrier. The formation process (E)-Pro consists of the following five steps: hydride H1-shift, conformational isomerism 1, hydride H2-shift, conformational isomerism 2, and olefin coordination process. Topological analysis shows that there is a five-membered ring plane structure in the reaction pathway and that the final product (E)-Pro belongs to a typical η2-olefin monohydride complex. Our calculated results provide an explanation for experimental observations and useful insights for further development of olefin functionalization. © 2019 Wiley Periodicals, Inc. 相似文献
45.
46.
Xinfeng Zhu Yanli Mao Hongpan Liu Haiyan Kang Biao Liu Zhongxian Song Xueping Liu Yifei Guo Huixian Du Qiulin Zhang 《应用有机金属化学》2020,34(2):e5285
FeOx, TiO2, and Fe–Ti–Ox catalysts were synthesized and used in the catalytic hydrolysis of hydrogen cyanide (HCN). Nearly 100% HCN conversion was achieved at 250 °C over the Fe–Ti–Ox catalyst. TiO2 rutile was detected over TiO2, but not over Fe–Ti–Ox, which suggested that the interaction between Fe and Ti species could inhibit the TiO2 phase transition. Furthermore, the interaction between Fe and Ti species over Fe–Ti–Ox could promote the selectivity of NH3 and CO. The mechanism of hydrolysis of HCN over FeOx, TiO2, and Fe–Ti–Ox can be given as follows: HCN + H2O → methanamide → ammonium formate → formic acid → H2O + CO. 相似文献
47.
Alpha-phenylethanol (PE) is an essential chemical in the field of medicine and synthetic perfumery. Therefore, in this work, we used a supported Ni–B–P amorphous alloy catalyst (Ni–B–P/SiO2) in the hydrogenation of acetophenone (AP) to α-PE, which demonstrated excellent catalytic activity and selectivity, compared with Ni–B/SiO2 (KBH4 reduction of nickel salt). Ni–B–P/SiO2 exhibited a high AP hydrogenation conversion of approximately 99%, whereas the PE selectivity reached up to 94%, which is approximately 1.4-fold higher than that of Ni–B/SiO2 (about 69%), thereby directly proving the unique inhibition of AP hydrogenation over hydrogenation of P in the Ni–B catalytic system. The doped P in Ni–B–P/SiO2 enhances the oxidation resistance and maintains the valence stability of Ni and B. Furthermore, sufficient experimental data were collected to determine the kinetic parameters. Based on the Langmuir–Hinshelwood model, we assumed that (i) AP and H2 compete for adsorption on Ni–B–P/SiO2; (ii) AP has strong adsorptive capacity on Ni–B–P/SiO2; and (iii) PE coverage on the catalyst was negligible. Then, the dynamic equation was derived, which indicated that experimental data agree well with the dynamic model. Finally, the activation energy was confirmed to be 50.73 KJ/mol. This report will open up an avenue for the industrialization of amorphous alloy catalysts. 相似文献
48.
The insertion of an alkyne into transition metal–hydrogen bonds is a key elementary step in catalytic polymerization and hydrogenation processes. It was found that a (Z)- or (E)-type alkyenyl complex can be formed through trans/cis stereospecific processes. In this work, the reaction mechanism of Cp2M(L)H [Cp = η5-C5H5; M = Nb, V; L = CO, P (OMe)3] with dimethylacetylene dicarboxylate (DMAD), and the factors influencing the stereoselectivity have been investigated based on density functional theory calculations. The calculated results show that all of the reactions are exothermic. For L = CO, the Z-isomer product forms first even at low temperatures because of the low Gibbs free energy barrier (ΔG#). Then the Z-pro converts to E-pro , while for L = P (OMe)3, the exclusive product is the E-isomer. For different metal centers, the reaction mechanisms of the Cp2M(CO)H + DMAD (M = Nb and V) reaction are similar, while their products are different at room temperature. For M = Nb, because the energy barrier of the isomerization from Z-pro to E-pro is low and the relative free energies of Z-pro and E-pro are almost equal, both Z-pro and E-pro can be obtained. While for the Cp2V(CO)H + DMAD reaction, only the Z-pro can be obtained under mild conditions, E-pro can be obtained only at high temperatures. For the Cp2M(CO)H+DMAD(M=V and Nb) reactions, the formation of E-isomer products proceeds via two five-membered ring transition states. The calculated results provide an reasonable explanation for the experimental results and predict a new insertion reaction. 相似文献
49.
The initial stage of electrodeposition of manganese dioxide has been studied on the platinum disk electrode and on the ring-disk electrode. Two current maxima were observed on the anodic voltammograms. It has been shown that the first rise in the current is associated with the formation of manganese dioxide (MD) nuclei on the electrode surface, and the second with their growth at the border between MnO2 and bare platinum due to an increase in the perimeter of the nuclei. Electrodeposition on bare platinum proceeds at a higher rate than on the surface of growing MD. This is explained by the difference in the reaction mechanisms on these substrates. The first stage of the process on the growing MD is the chemisorption of Mn(II) ions with the formation of Mn(III) ions, which are then electrochemically oxidized to MD. Chemisorption is the slowest step in the whole process. 相似文献
50.
当周期激励频率远小于系统固有频率时,会存在快慢耦合效应,与单项激励不同,参外联合激励不仅会导致快子系统平衡曲线和分岔行为的复杂化,也会产生一些特殊的非线性现象,为此,本文以两耦合Hodgkin-Huxley细胞模型为例,引入周期参外联合激励,探讨在频域不同尺度耦合时该系统的簇发振荡的特点及其分岔机制.通过建立相应的快慢子系统,得到慢变参数变化下的快子系统的各种分岔模式以及相应的分岔行为,结合转换相图,揭示耦合系统随激励幅值变化时的动力学行为及其机理.研究表明,在激励幅值较小时,系统表现为概周期振荡,两频率分别近似于快子系统平衡曲线由Hopf分岔引起的两稳定极限环的振荡频率.概周期解随激励幅值的增加进入簇发振荡,导致这些簇发振荡的主要原因是在慢变参数变化的部分区间内,存在唯一稳定的平衡曲线,使得系统的轨迹逐渐趋向该平衡曲线,产生沉寂态,并随着慢变参数的变化,由分岔进入激发态.同时,快子系统中参与簇发振荡的稳定吸引子随激励幅值的变化也会不同,导致不同形式的簇发振荡.另外,与单项激励下的情形不同,联合激励时快子系统的部分稳定吸引子掩埋在其它稳定吸引子内,从而失去对簇发振荡的影响. 相似文献