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992.
993.
双铜簇合物的EPR谱、磁性与电子结构研究 总被引:1,自引:0,他引:1
本文报导了77K及室温下新合成的双铜簇合物(DMF)2]·4DMF的EPR及磁性测定结果。所得到的三套EPR谱与磁矩以及Scc-EHMO量化计算结果综合分析,确认两套谱归属于铜离子上的未配对电子,另一套归属于簇合物三重态电子。固态时顺磁性主要是三重态的贡献,溶液时主要来自铜离子。
该簇合物的电子结构特点:双铜之间有微弱作用。双铜与桥基、端基成键后的剩余价态很少,铜离子上的电子自旋浓度约为单铜化合物的3%,因此铜离子的两套EPR谱强度相当弱。分子轨道前沿的能级接近简并,轨道上的电子形成热激发三重态,造成一套三重态EPR谱。因此,可认为该化合物是一种新型自身磁稀释的三重态双铜簇合物。 相似文献
994.
995.
Voltammetric Lead Determination in Aviation Fuel Samples Using a Screen‐Printed Gold Electrode and Batch‐Injection Analysis 下载免费PDF全文
This work presents the lead determination in aviation (bio)fuels using disposable screen‐printed gold electrodes (SPGEs) adapted on a batch‐injection cell associated with a micropipette for portable analysis. The method involves injections of 200 µL of sample or standard solutions at controlled dispensing rate (4.8 µL s?1) during deposition step (?550 mV for 90 s), followed by anodic‐stripping voltammetry. Either samples treated by sonication or dry‐ashing can be analyzed with detection limits of 0.0071 and 0.0008 µg g?1 Pb, respectively. A single SPGE can be applied for 60 consecutive measurements (or 120 for samples dry‐ashed). The ultrasound‐assisted treatment is faster, safer, and easily adapted for on‐site analyses, especially considering the portable characteristics of commercially‐available potentiostats and batch‐injection analysis cell using SPGEs. 相似文献
996.
Dr. Sailin Liu Dr. Jitraporn Vongsvivut Yanyan Wang Ruizhi Zhang Dr. Fuhua Yang Dr. Shilin Zhang Prof. Kenneth Davey Dr. Jianfeng Mao Prof. Zaiping Guo 《Angewandte Chemie (International ed. in English)》2023,62(4):e202215600
Zinc metal battery (ZMB) is promising as the next generation of energy storage system, but challenges relating to dendrites and corrosion of the zinc anode are restricting its practical application. Here, to stabilize Zn anode, we report a controlled electrolytic method for a monolithic solid-electrolyte interphase (SEI) via a high dipole moment solvent dimethyl methylphosphonate (DMMP). The DMMP-based electrolytes can generate a homogeneous and robust phosphate SEI (Zn3(PO4)2 and ZnP2O6). Benefiting from the protecting impact of this in situ monolithic SEI, the zinc electrode exhibits long-term cycling of 4700 h and a high Coulombic efficiency 99.89 % in Zn|Zn and Zn|Cu cell, respectively. The full V2O5|Zn battery with DMMP-H2O hybrid electrolyte exhibits a high capacity retention of 82.2 % following 4000 cycles under 5 A g−1. The first success in constructing the monolithic phosphate SEI will open a new avenue in electrolyte design for highly reversible and stable Zn metal anodes. 相似文献
997.
Dr. Tianjun Chang Guangping Li Dingran Chang Ryan Amini Xiaoni Zhu Prof. Tongqian Zhao Jimmy Gu Prof. Zhongping Li Prof. Yingfu Li 《Angewandte Chemie (International ed. in English)》2023,62(42):e202310941
Engineering functional nucleic acids that are active under unusual conditions will not only reveal their hidden abilities but also lay the groundwork for pursuing them for unique applications. Although many DNAzymes have been derived to catalyze diverse chemical reactions in aqueous solutions, no prior study has been set up to purposely derive DNAzymes that require an organic solvent to function. Herein, we utilized in vitro selection to isolate RNA-cleaving DNAzymes from a random-sequence DNA pool that were “compelled” to accept 35 % dimethyl sulfoxide (DMSO) as a cosolvent, via counter selection in a purely aqueous solution followed by positive selection in the same solution containing 35 % DMSO. This experiment led to the discovery of a new DNAzyme that requires 35 % DMSO for its catalytic activity and exhibits drastically reduced activity without DMSO. This DNAzyme also requires divalent metal ions for catalysis, and its activity is enhanced by monovalent ions. A minimized, more efficient DNAzyme was also derived. This work demonstrates that highly functional, organic solvent-dependent DNAzymes can be isolated from random-sequence DNA libraries via forced in vitro selection, thus expanding the capability and potential utility of catalytic DNA. 相似文献
998.
Renat R. Nazmutdinov Michael D. Bronshtein Dmitrii V. Glukhov Tamara T. Zinkicheva 《Journal of Solid State Electrochemistry》2008,12(4):445-451
Solvent dynamics effects on the electroreduction of [PtCl3(H2O)]− at a mercury electrode are explored in the framework of Sumi–Marcus model using an efficient computational scheme. According
to results of density functional calculations, the second electron transfer step may be regarded as rate controlling. The
nonmonotonous influence of solvent viscosity on the reaction rate is predicted and explained in terms of the saddle point
avoidance. The results of model calculations are employed to interpret experimental data reported earlier in the literature.
相似文献
Renat R. NazmutdinovEmail: |
999.
In this study, a series of new 5-phenylazo-6-aminouracil dyes were prepared by linking m-,p-nitroaniline, m-,p-chloroaniline,
m-,p-anisidine, m-,p-toluidine, m-,p-cyanoaniline, p-ethoxyaniline, p-phenoxyaniline, p-ethylaniline, p-acetamidoaniline,
p-acetylaniline, p-carboxyaniline and aniline to 6-aminouracil. The prepared dyes were characterized by UV-vis, FT-IR, 1H NMR spectroscopic techniques and elemental analysis. The effect of acid and base upon the UV-vis spectra of these dyes were
investigated. In addition, the solvatochromic behaviors and substituent effects in various solvents were evaluated.
相似文献
1000.
糠醛催化加氢反应工艺主要分为气相、液相以及催化转移加氢等.相比于糠醛气相加氢,液相加氢为反应提供了更多的可持续性和自由度,但其中溶剂依赖现象对糠醛定向催化转化的影响机制尚不清晰.针对上述问题,本文选用3种溶剂(甲醇、水和环己烷)为研究对象,采用密度泛函方法,从理论计算角度探究了Pd催化糠醛加氢反应中溶剂效应对反应活性和选择性的重要作用.结果表明,在糠醛加氢反应过程中,溶剂一方面能够形成氢键网络促进质子穿梭,另一方面能够稳定反应物、中间体以及生成物,有效降低C=O加氢的能垒.自由能计算结果表明,在液态水、甲醇和环己烷中,随着溶剂极性的降低(水>甲醇>环己烷),第一步C=O氢化的能垒逐渐降低(0.70 eV>0.68 eV>0.44 eV).在水和甲醇介导的糠醛加氢反应过程中,第一步C=O加氢的反应势垒进一步降低为0.47和0.41 eV.差分电荷密度以及Bader电荷分析表明,反应过程中存在糠醛和Pd催化剂之间的电荷转移.分波态密度(PDOS)分析表明,溶剂的加入使d带中心向靠近费米能级的方向移动,表明Pd催化剂的催化活性得到提高. 相似文献