Catalytic Hydrogenation of CO2 by Unsymmetric N−Heterocyclic Carbene−Nitrogen−Phosphine Ruthenium Complexes

2021 ◽  
Author(s):  
Li Ji ◽  
TIanhua Cui ◽  
Xufeng Nie ◽  
Yanling Zheng ◽  
Xueli Zheng ◽  
...  
Keyword(s):  
High Activity ◽  
Catalytic Hydrogenation ◽  
Ruthenium Complexes ◽  
Hydrogenation Of Co2 ◽  
First Time ◽  
Excellent Stability

Unsymmetric Ru-CNP and Ru-CN(H)P complexes are synthesized and applied in hydrogenation of CO2 to formate for the first time. Ru-CNP complex shows excellent stability and high activity. The TON is...

Catalytic hydrogenation of carbonyl and nitro compounds using an [N,O]-chelate half-sandwich ruthenium catalyst

2019 ◽  
Vol 48 (21) ◽  
pp. 7158-7166 ◽  
Author(s):  
Zi-Jian Yao ◽  
Jing-Wei Zhu ◽  
Nan Lin ◽  
Xin-Chao Qiao ◽  
Wei Deng
Keyword(s):  
Aqueous Solution ◽  
High Activity ◽  
Catalytic Hydrogenation ◽  
Ruthenium Complexes ◽  
Nitro Compounds ◽  
Ruthenium Catalyst ◽  
Half Sandwich

A series of N,O-chelate half-sandwich ruthenium complexes have been synthesized, which exhibited high activity for the catalytic hydrogenation of carbonyl and nitro compounds in aqueous solution.

Iridium-Catalyzed Silylation of C-H bonds in Unactivated Arenes: A Sterically-Encumbered Phenanthroline Ligand Accelerates Catalysis Enabling New Reactivity

2019 ◽  
Author(s):  
Caleb Karmel ◽  
Zhewei Chen ◽  
John Hartwig
Keyword(s):  
High Activity ◽  
Functional Group ◽  
Activity Analysis ◽  
High Reactivity ◽  
High Yield ◽  
Phen Ligand ◽  
Mechanistic Studies ◽  
Phenanthroline Ligand ◽  
First Time ◽  
New System

We report a new system for the silylation of aryl C-H bonds. The combination of [Ir(cod)(OMe)]<sub>2</sub> and 2,9-Me<sub>2</sub>-phenanthroline (2,9-Me<sub>2</sub>phen) catalyzes the silylation of arenes at lower temperatures and with faster rates than those reported previously, when the hydrogen byproduct is removed, and with high functional group tolerance and regioselectivity. Inhibition of reactions by the H<sub>2</sub> byproduct is shown to limit the silylation of aryl C-H bonds in the presence of the most active catalysts, thereby masking their high activity. Analysis of initial rates uncovered the high reactivity of the catalyst containing the sterically hindered 2,9-Me<sub>2</sub>phen ligand but accompanying rapid inhibition by hydrogen. With this catalyst, under a flow of nitrogen to remove hydrogen, electron-rich arenes, including those containing sensitive functional groups, undergo silylation in high yield for the first time, and arenes that underwent silylation with prior catalysts react over much shorter times with lower catalyst loadings. The synthetic value of this methodology is demonstrated by the preparation of key intermediates in the synthesis of medicinally important compounds in concise sequences comprising silylation and functionalization. Mechanistic studies demonstrate that the cleavage of the aryl C-H bond is reversible and that the higher rates observed with the 2,9-Me<sub>2</sub>phen ligand is due to a more thermodynamically favorable oxidative addition of aryl C-H bonds.

scholarly journals Ruthenium Sensitizers and Their Applications in Dye-Sensitized Solar Cells

2012 ◽  
Vol 2012 ◽  
pp. 1-21 ◽  
Author(s):  
Yuancheng Qin ◽  
Qiang Peng
Keyword(s):  
Solar Cells ◽  
High Efficiency ◽  
Low Cost ◽  
Dye Sensitized Solar Cells ◽  
Ruthenium Complexes ◽  
Practical Applications ◽  
Photovoltaic Energy ◽  
Dye Sensitized ◽  
Sensitized Solar Cells ◽  
Excellent Stability

Dye-sensitized solar cells (DSSCs) have attracted considerable attention in recent years due to the possibility of low-cost conversion of photovoltaic energy. The DSSCs-based ruthenium complexes as sensitizers show high efficiency and excellent stability, implying potential practical applications. This review focuses on recent advances in design and preparation of efficient ruthenium sensitizers and their applications in DSSCs, including thiocyanate ruthenium sensitizers and thiocyanate-free ruthenium sensitizers.

scholarly journals Fractionation of Birch Wood by Integrating Alkaline-Acid Treatments and Hydrogenation in Ethanol over a Bifunctional Ruthenium Catalyst

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1362
Author(s):  
Boris N. Kuznetsov ◽  
Sergey V. Baryshnikov ◽  
Angelina V. Miroshnikova ◽  
Aleksandr S. Kazachenko ◽  
Yuriy N. Malyar ◽  
...  
Keyword(s):  
Microcrystalline Cellulose ◽  
Catalytic Hydrogenation ◽  
Liquid Product ◽  
Gel Permeation Chromatography ◽  
Ruthenium Catalyst ◽  
Birch Wood ◽  
Gaseous Products ◽  
Liquid Products ◽  
First Time

For the first time, the fractionation of birch wood into microcrystalline cellulose, xylose and methoxyphenols is suggested based on the integration of alkali-acid pretreatments and hydrogenation in ethanol over a bifunctional Ru/C catalyst. It is established that removal of hemicelluloses during pretreatments of birch wood influences the yields of the liquid, gaseous and solid products of the non-catalytic and catalytic hydrogenation of pretreated samples in ethanol at 225 °C. The bifunctional Ru/carbon catalyst affects in different ways the conversion and yields of products of hydrogenation of the initial and acid- and alkali-pretreated birch wood. The most noticeable influence is characteristic of the hydrogenation of the acid-pretreated wood, where in contrast to the non-catalytic hydrogenation, the wood conversion and the yields of liquid products increase but the yields of the solid and gaseous products decrease. GC-MS, gel permeation chromatography and elemental analysis were used for characterization of the liquid product composition. The molecular mass distribution of the liquid products of hydrogenation of the initial and pretreated wood shifts towards the low-molecular range in the presence of the catalyst. From the GC-MS data, the contents of monomer compounds, predominantly 4-propylsyringol and 4-propanolsyringol, increase in the presence of the ruthenium catalyst. The solid products of catalytic hydrogenation of the pretreated wood contain up to 95 wt% of cellulose with the structure, similar to that of microcrystalline cellulose.

scholarly journals Cyclam-Based Chelators Bearing Phosphonated Pyridine Pendants for 64Cu-PET Imaging : Synthesis, Physico-Chemical Studies, Radiolabeling and Bioimaging.

2020 ◽  
Author(s):  
Richard Knighton ◽  
Thibault Troadec ◽  
Valerie Mazan ◽  
Patricia La Saëc ◽  
Séverine Marionneau-Lambot ◽  
...  
Keyword(s):  
Pet Imaging ◽  
Copper Complexes ◽  
The Body ◽  
Renal Elimination ◽  
X Ray Diffraction ◽  
Physico Chemical ◽  
Chemical Studies ◽  
First Time ◽  
Excellent Stability

Herein we present the preparation of two novel cyclam-based macrocycles (te1pyp and cb-te1pyp), bearing phosphonate-appended pyridine side-arms for the coordination of copper(II) ions in the context of 64Cu PET imaging. The two ligands have been prepared through conventional protection-alkylation sequences on cyclam, and their coordination properties have been thoroughly investigated. The corresponding copper complexes have been fully characterized in the solid-state (X-Ray diffraction analysis) and in solution (EPR and UV-Vis spectroscopies). Potentiometric studies, combined with spectrometry, have also allowed us to determine their thermodynamic stability constants, confirming their high affinity for copper(II) cations. The kinetic inertness of the complexes has also been verified by acid-assisted dissociation experiments, enabling their use in 64Cu-PET imaging in mice for the first time. Indeed, the two ligands could be quantitatively radiolabeled under mild conditions, and the resulting 64Cu complexes have demonstrated excellent stability in serum. PET imaging demon-strated a set of features emerging from the combination of picolinates and phosphonate units: high stability in vivo, fast clear-ance from the body via renal elimination, and most interestingly, very low fixation in the liver. The latter is in contrast with what was observed for monopicolinate cyclam (te1pa), that had a non-negligible accumulation in the liver, owing probably to its different charge and lipophillicity. These results thus pave the way for the use of such phosphonated pyridine chelators for in vivo 64Cu-PET imaging.

scholarly journals Cyclam-Based Chelators Bearing Phosphonated Pyridine Pendants for 64Cu-PET Imaging : Synthesis, Physico-Chemical Studies, Radiolabeling and Bioimaging.

2020 ◽  
Author(s):  
Richard Knighton ◽  
Thibault Troadec ◽  
Valerie Mazan ◽  
Patricia La Saëc ◽  
Séverine Marionneau-Lambot ◽  
...  
Keyword(s):  
Pet Imaging ◽  
Copper Complexes ◽  
The Body ◽  
Renal Elimination ◽  
X Ray Diffraction ◽  
Physico Chemical ◽  
Chemical Studies ◽  
First Time ◽  
Excellent Stability

Herein we present the preparation of two novel cyclam-based macrocycles (te1pyp and cb-te1pyp), bearing phosphonate-appended pyridine side-arms for the coordination of copper(II) ions in the context of 64Cu PET imaging. The two ligands have been prepared through conventional protection-alkylation sequences on cyclam, and their coordination properties have been thoroughly investigated. The corresponding copper complexes have been fully characterized in the solid-state (X-Ray diffraction analysis) and in solution (EPR and UV-Vis spectroscopies). Potentiometric studies, combined with spectrometry, have also allowed us to determine their thermodynamic stability constants, confirming their high affinity for copper(II) cations. The kinetic inertness of the complexes has also been verified by acid-assisted dissociation experiments, enabling their use in 64Cu-PET imaging in mice for the first time. Indeed, the two ligands could be quantitatively radiolabeled under mild conditions, and the resulting 64Cu complexes have demonstrated excellent stability in serum. PET imaging demon-strated a set of features emerging from the combination of picolinates and phosphonate units: high stability in vivo, fast clear-ance from the body via renal elimination, and most interestingly, very low fixation in the liver. The latter is in contrast with what was observed for monopicolinate cyclam (te1pa), that had a non-negligible accumulation in the liver, owing probably to its different charge and lipophillicity. These results thus pave the way for the use of such phosphonated pyridine chelators for in vivo 64Cu-PET imaging.

scholarly journals A brief review on the reaction mechanisms of CO2 hydrogenation into methanol

2020 ◽  
Vol 3 (2) ◽  
pp. 33-40
Author(s):  
Jawed Qaderi
Keyword(s):  
Catalytic Hydrogenation ◽  
Density Functional ◽  
Heterogeneous Catalysts ◽  
Catalytic Reduction ◽  
Kinetic Monte Carlo ◽  
Low Cost ◽  
Hydrogenation Of Co2 ◽  
Fuel Prices ◽  
Metal Metal ◽  
Reduction Of Co2

The catalytic reduction of CO2 to methanol is an appealing option to reduce greenhouse gas concentration as well as renewable energy production. In addition, the exhaustion of fossil fuel, increase in earth temperature and sharp increases in fuel prices are the main driving factor for exploring the synthesis of methanol by hydrogenating CO2. Many studies on the catalytic hydrogenation of CO2 to methanol were published in the literature over the last few decades. Many of the studies have presented different catalysts having high stability, higher performance, low cost, and are immediately required to promote conversion. Understanding the mechanisms involved in the conversion of CO2 is essential as the first step towards creating these catalysts. This review briefly summarizes recent theoretical developments in mechanistic studies focused on using density functional theory, kinetic Monte Carlo simulations, and microkinetics modeling. Based on these simulation techniques on different transition metals, metal/metal oxide, and other heterogeneous catalysts surfaces, mainly, three important mechanisms that have been recommended are the formate (HCOO), reverse water–gas shift (RWGS), and trans-COOH mechanisms. Recent experimental and theoretical efforts appear to demonstrate that the formate route in which the main intermediate species is H2CO* in the reaction route, is more favorable in catalytic hydrogenation of CO2 to chemical fuels in various temperature and pressure conditions.

Single Pd atomic catalyst on Mo2CO2 monolayer (MXene): unusual activity for CO oxidation by trimolecular Eley–Rideal mechanism

2018 ◽  
Vol 20 (5) ◽  
pp. 3504-3513 ◽  
Author(s):  
Cheng Cheng ◽  
Xilin Zhang ◽  
Mingyang Wang ◽  
Shiyan Wang ◽  
Zongxian Yang
Keyword(s):  
Co Oxidation ◽  
High Activity ◽  
Excellent Stability

A Pd atom Mo2CO2 exhibits excellent stability and high activity to CO oxidation.

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