Influence of spin state and electron configuration on the active site and mechanism for catalytic hydrogenation on metal cation catalysts supported on NU-1000: insights from experiments and microkinetic modeling

2020 ◽  
Vol 10 (11) ◽  
pp. 3594-3602 ◽  
Author(s):  
Hafeera Shabbir ◽  
Steven Pellizzeri ◽  
Magali Ferrandon ◽  
In Soo Kim ◽  
Nicolaas A. Vermeulen ◽  
...  
Keyword(s):  
Spin State ◽  
Catalytic Hydrogenation ◽  
Metal Cation ◽  
Active Site ◽  
Electron Configuration ◽  
Microkinetic Modeling

Spin state is found to determine the mechanism and active site of catalytic hydrogenation on metal cation catalysts.

Atomically dispersed Ni as the active site towards selective hydrogenation of nitroarenes

2019 ◽  
Vol 21 (3) ◽  
pp. 704-711 ◽  
Author(s):  
Fan Yang ◽  
Minjian Wang ◽  
Wei Liu ◽  
Bin Yang ◽  
Ying Wang ◽  
...  
Keyword(s):  
Noble Metal ◽  
Catalytic Hydrogenation ◽  
Selective Hydrogenation ◽  
Porous Carbon ◽  
Active Site ◽  
Active Sites ◽  
Rational Design ◽  
Metal Free

Noble-metal-free catalytic hydrogenation of nitroarenes is achieved through the rational design of atomically dispersed Ni sites on N-doped porous carbon. The outstanding activity of the catalyst originates from the atomic dispersion of Ni active sites with a high Ni–N3 content.

μ-Hydroxo-μ-phenolato Dinuclear Nickel(II) Complexes in a Mixed-Spin State and Their Urea Adduct as Relevance to the Urease Active Site

2005 ◽  
Vol 78 (10) ◽  
pp. 1814-1820 ◽  
Author(s):  
Rie Amase ◽  
Hitomi Shiraishi ◽  
Yuji Miyasato ◽  
Masaaki Ohba ◽  
Hisashi Okawa
Keyword(s):  
Spin State ◽  
Active Site ◽  
Urea Adduct ◽  
Mixed Spin

scholarly journals Contribution of the active-site metal cation to the catalytic activity and to the conformational stability of phosphotriesterase: temperature- and pH-dependence

2004 ◽  
Vol 380 (3) ◽  
pp. 627-633 ◽  
Author(s):  
Daniel ROCHU ◽  
Nathalie VIGUIÉ ◽  
Frédérique RENAULT ◽  
David CROUZIER ◽  
Marie-Thérèse FROMENT ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Metal Cation ◽  
Active Site ◽  
Ph Dependence ◽  
Conformational Stability ◽  
Maximum Activity ◽  
Active Centre ◽  
Optimum Activity ◽  
Maximum Stability ◽  
Activation Phase

Phosphotriesterase (PTE) detoxifies nerve agents and organophosphate pesticides. The two zinc cations of the PTE active centre can be substituted by other transition metal cations without loss of activity. Furthermore, metal-substituted PTEs display differences in catalytic properties. A prerequisite for engineering highly efficient mutants of PTE is to improve their thermostability. Isoelectric focusing, capillary electrophoresis and steady-state kinetics analysis were used to determine the contribution of the active-site cations Zn2+, Co2+ or Cd2+ to both the catalytic activity and the conformational stability of the corresponding PTE isoforms. The three isoforms have different pI values (7.2, 7.5 and 7.1) and showed non-superimposable electrophoretic titration curves. The overall structural alterations, causing changes in functional properties, were found to be related to the nature of the bound cation: ionic radius and ion electronegativity correlate with Km and kcat respectively. In addition, the pH-dependent activity profiles of isoforms were different. The temperature-dependent profiles of activity showed maximum activity at T≤35 °C, followed by an activation phase near 45–48 °C and then inactivation which was completed at 60 °C. Analysis of thermal denaturation of the PTEs provided evidence that the activation phase resulted from a transient intermediate. Finally, at the optimum activity between pH 8 and 9.4, the thermostability of the different PTEs increased as the pH decreased, and the metal cation modulated stability (Zn2+-, Co2+- and Cd2+-PTE showed different Tm values of 60.5–67 °C, 58–64 °C and 53–64 °C respectively). Requirements for optimum activity of PTE (displayed by Co2+-PTE) and maximum stability (displayed by Zn2+-PTE) were demonstrated.

scholarly journals Aryl bis-sulfonamides bind to the active site of a homotrimeric isoprenoid biosynthesis enzyme IspF and extract the essential divalent metal cation cofactor

2018 ◽  
Vol 9 (27) ◽  
pp. 5976-5986 ◽  
Author(s):  
Katharina Root ◽  
Konstantin Barylyuk ◽  
Anatol Schwab ◽  
Jonas Thelemann ◽  
Boris Illarionov ◽  
...  
Keyword(s):  
Protein Binding ◽  
Metal Cation ◽  
Active Site ◽  
Divalent Metal ◽  
Isoprenoid Biosynthesis ◽  
Divalent Metal Cation ◽  
Esi Ms ◽  
Binding Mechanisms ◽  
Insight Into

Native ESI-MS delivers unprecedented insight into unknown homomeric protein binding mechanisms involving complex, multistage binding equilibria with cofactors and ligands.

Electronic structure of five- and six-coordinate iron(III) tetraazaporphyrin complexes: pyrrole-Cαchemical shift as a useful probe

2008 ◽  
Vol 12 (09) ◽  
pp. 1041-1049 ◽  
Author(s):  
Takahisa Ikeue ◽  
Satoshi Kurahashi ◽  
Makoto Handa ◽  
Tamotu Sugimori ◽  
Mikio Nakamura
Keyword(s):  
Electronic Structure ◽  
Spin State ◽  
Electron Configuration ◽  
Hydrogen Atoms ◽  
Nmr Studies ◽  
Chloride Complexes ◽  
H Nmr ◽  
Intermediate Spin ◽  
Intermediate Spin State ◽  
C Nmr

Electronic structure of a series of five-coordinate Fe ( OArTAzP ) X ( OAr = octaaryltetraazaporphyrin , X = Cl-, Br-, I-; Ar = 4-tert-butylphenyl) have been examined on the basis of1H NMR,13C NMR, and EPR spectroscopy as well as SQUID magnetometry. These complexes adopt the intermediate-spin state as in the case of analogous complexes reported by Fitzgerald et al. (Inorg. Chem. 1992; 31: 2006-2013) and Stuzhin et al. (Inorg. Chim. Acta 1995; 236: 131-139). The13C NMR studies using13C -enriched complexes at the pyrrole α positions have revealed that the pyrrole- Cαsignals appear at extraordinary upfield positions, i.e. -130 to -250 ppm at 273 K, due to the dz2-a2 uand dπ-3 eginteractions. The Curie plots of the pyrrole- Cαsignals have further revealed that the iodide complex adopts a much purer intermediate-spin state than the bromide and chloride complexes. In contrast to the case of Fe ( OArTAzP ) X , six-coordinate [ Fe ( OArTAzP )( CN )2]-showed the pyrrole- Cαsignal at 47 ppm at 273 K, which indicates that the complex adopts the low-spin state with the ( dxy)2( dxz, dyz)3electron configuration. Thus, the13C NMR chemical shift of the pyrrole- Cαsignal turns out to be quite a good probe to elucidate the spin state and electron configuration of iron(III) tetraazaporphyrins, where the1H NMR spectroscopy is less useful because of the absence of the hydrogen atoms as well as the alkyl or aryl groups directly attached to the meso positions.

Ab initio coverage-dependent microkinetic modeling of benzene hydrogenation on Pd(111)

2017 ◽  
Vol 7 (22) ◽  
pp. 5267-5283 ◽  
Author(s):  
Maarten K. Sabbe ◽  
Gonzalo Canduela-Rodriguez ◽  
Jean-François Joly ◽  
Marie-Françoise Reyniers ◽  
Guy B. Marin
Keyword(s):  
Ab Initio ◽  
Catalytic Hydrogenation ◽  
Benzene Hydrogenation ◽  
Microkinetic Modeling ◽  
Mechanistic Understanding

Coverage-dependent calculations are required for an accurate DFT-based prediction of the activity and a correct mechanistic understanding of catalytic hydrogenation.

scholarly journals Cation-exchanged zeolites for the selective oxidation of methane to methanol

2018 ◽  
Vol 8 (1) ◽  
pp. 114-123 ◽  
Author(s):  
Ambarish R. Kulkarni ◽  
Zhi-Jian Zhao ◽  
Samira Siahrostami ◽  
Jens K. Nørskov ◽  
Felix Studt
Keyword(s):  
Transition Metal ◽  
Selective Oxidation ◽  
Metal Cation ◽  
Active Site ◽  
Methane Activation ◽  
Transition Metal Cation ◽  
Trade Off ◽  
Oxidation Of Methane ◽  
Active Site Motif

Development of an ideal methane activation catalyst presents a trade-off between stability and reactivity of the active site that can be achieved by tuning the transition metal cation, active site motif and the zeolite topology.

Suppressing the active site-blocking impact of ligands of Ni6(SR)12 clusters with the assistance of NH3 on catalytic hydrogenation of nitriles

Nanoscale ◽  
2018 ◽  
Vol 10 (41) ◽  
pp. 19375-19382 ◽  
Author(s):  
Xiaoqi Chai ◽  
Tao Li ◽  
Mingyang Chen ◽  
Rongchao Jin ◽  
Weiping Ding ◽  
...  
Keyword(s):  
Catalytic Hydrogenation ◽  
Active Site ◽  
Shielding Effect ◽  
Site Blocking ◽  
Hydrogenation Of Nitriles

The activity of Ni6(SR)12 for nitriles hydrogenation is enhanced with the assistance of NH3 that suppresses the ligand shielding effect.

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