Second-coordination sphere effects on the reactivities of Hoveyda–Grubbs-type catalysts: a ligand exchange study using phenolic moiety-functionalized ligands

2020 ◽  
Vol 49 (33) ◽  
pp. 11618-11627 ◽  
Author(s):  
Catur Jatmika ◽  
Kenta Goshima ◽  
Kazumo Wakabayashi ◽  
Naoki Akiyama ◽  
Shun Hirota ◽  
...  
Keyword(s):  
Coordination Sphere ◽  
Ligand Exchange ◽  
Functional Group ◽  
Exchange Study ◽  
Second Coordination Sphere ◽  
Functionalized Ligands

The reactivities of Hoveyda–Grubbs-type complexes are tunable through second-coordination sphere effects caused by a functional group in the ligand.

Tuning Second Coordination Sphere Interactions in Polypyridyl–Iron Complexes to Achieve Selective Electrocatalytic Reduction of Carbon Dioxide to Carbon Monoxide

2019 ◽  
Author(s):  
David Zee ◽  
Michael Nippe ◽  
Amanda King ◽  
Christopher Chang ◽  
Jeffrey R. Long
Keyword(s):  
Carbon Dioxide ◽  
Coordination Sphere ◽  
Functional Group ◽  
Value Added ◽  
Acetonitrile Solution ◽  
Proton Source ◽  
Fe Complexes ◽  
Second Coordination Sphere ◽  
Functionalized Ligands ◽  
High Degree

The development of noble metal-free catalysts capable of electrochemically converting carbon dioxide (CO<sub>2</sub>) selectively into value added compounds remains one of the central challenges in sustainable energy science. Here, we present a systematic study of Fe(II) complexes of the functionalized ligands bpy<sup>R</sup>PY2Me (bpyPY2Me = 6-(1,1-di(pyridin-2-yl)ethyl)-2,2′-bipyridine) in pursuit of water-stable molecular Fe complexes that are selective for the catalytic formation of CO from CO<sub>2</sub>. Taking advantage of the inherently high degree of tunability of this ligand manifold, we followed a bio-inspired approach by installing protic functional groups of varying acidities (–H, –OH, –OMe, –NHEt, and –NEt2) into the ligand framework to systematically modify the second coordination sphere of the Fe center. This family of [(bpy<sup>R</sup>PY2Me)Fe(II)] complexes was characterized using single-crystal X-ray analysis, 1H NMR spectroscopy, and mass spectrometry. Comparative catalytic evaluation of this set of compounds via voltammetry and electrolysis experiments identified [(bpy<sup>NHEt</sup>PY2Me)Fe]<sup>2+</sup> in particular as an efficient, iron-based, non-heme CO<sub>2</sub> electro-reduction catalyst that displays significant selectivity for the conversion of CO<sub>2</sub> to CO in acetonitrile solution with 11 M H<sub>2</sub>O. We propose that the NH group acts as a local proton source for cleaving the C–O bond in CO<sub>2</sub> to form CO. Interestingly, the complex with the most acidic functional group in the second coordination sphere, [(bpy<sup>OH</sup>PY2Me)Fe]<sup>2+</sup>, favors formation of H<sub>2</sub> over CO. Our results correlate the selectivity of water versus carbon dioxide reduction to the acidity of the second coordination sphere functional group and emphasize the continued untapped potential that synthetic molecular chemistry offers in the pursuit of next-generation CO<sub>2</sub> reduction electrocatalysts.<br>

Tuning Second Coordination Sphere Interactions in Polypyridyl–Iron Complexes to Achieve Selective Electrocatalytic Reduction of Carbon Dioxide to Carbon Monoxide

2019 ◽  
Author(s):  
David Zee ◽  
Michael Nippe ◽  
Amanda King ◽  
Christopher Chang ◽  
Jeffrey R. Long
Keyword(s):  
Carbon Dioxide ◽  
Coordination Sphere ◽  
Functional Group ◽  
Value Added ◽  
Acetonitrile Solution ◽  
Proton Source ◽  
Fe Complexes ◽  
Second Coordination Sphere ◽  
Functionalized Ligands ◽  
High Degree

The development of noble metal-free catalysts capable of electrochemically converting carbon dioxide (CO<sub>2</sub>) selectively into value added compounds remains one of the central challenges in sustainable energy science. Here, we present a systematic study of Fe(II) complexes of the functionalized ligands bpy<sup>R</sup>PY2Me (bpyPY2Me = 6-(1,1-di(pyridin-2-yl)ethyl)-2,2′-bipyridine) in pursuit of water-stable molecular Fe complexes that are selective for the catalytic formation of CO from CO<sub>2</sub>. Taking advantage of the inherently high degree of tunability of this ligand manifold, we followed a bio-inspired approach by installing protic functional groups of varying acidities (–H, –OH, –OMe, –NHEt, and –NEt2) into the ligand framework to systematically modify the second coordination sphere of the Fe center. This family of [(bpy<sup>R</sup>PY2Me)Fe(II)] complexes was characterized using single-crystal X-ray analysis, 1H NMR spectroscopy, and mass spectrometry. Comparative catalytic evaluation of this set of compounds via voltammetry and electrolysis experiments identified [(bpy<sup>NHEt</sup>PY2Me)Fe]<sup>2+</sup> in particular as an efficient, iron-based, non-heme CO<sub>2</sub> electro-reduction catalyst that displays significant selectivity for the conversion of CO<sub>2</sub> to CO in acetonitrile solution with 11 M H<sub>2</sub>O. We propose that the NH group acts as a local proton source for cleaving the C–O bond in CO<sub>2</sub> to form CO. Interestingly, the complex with the most acidic functional group in the second coordination sphere, [(bpy<sup>OH</sup>PY2Me)Fe]<sup>2+</sup>, favors formation of H<sub>2</sub> over CO. Our results correlate the selectivity of water versus carbon dioxide reduction to the acidity of the second coordination sphere functional group and emphasize the continued untapped potential that synthetic molecular chemistry offers in the pursuit of next-generation CO<sub>2</sub> reduction electrocatalysts.<br>

A first-principles study of the atomic layer deposition of ZnO on carboxyl functionalized carbon nanotubes: the role of water molecules

2021 ◽  
Vol 23 (5) ◽  
pp. 3467-3478
Author(s):  
J. I. Paez-Ornelas ◽  
H. N. Fernández-Escamilla ◽  
H. A. Borbón-Nuñez ◽  
H. Tiznado ◽  
Noboru Takeuchi ◽  
...  
Keyword(s):  
First Principles ◽  
Ligand Exchange ◽  
Functional Group ◽  
Atomic Layer ◽  
High Reactivity ◽  
Water Molecules ◽  
Exchange Reactions ◽  
Layer Deposition ◽  
The Right

Atomic description of ALD in systems that combine large surface area and high reactivity is key for selecting the right functional group to enhance the ligand-exchange reactions.

scholarly journals Recent advances in metalloporphyrin-based catalyst design towards carbon dioxide reduction: from bio-inspired second coordination sphere modifications to hierarchical architectures

2020 ◽  
Vol 49 (8) ◽  
pp. 2381-2396 ◽  
Author(s):  
Philipp Gotico ◽  
Zakaria Halime ◽  
Ally Aukauloo
Keyword(s):  
Carbon Dioxide ◽  
Coordination Sphere ◽  
Three Dimensional ◽  
Carbon Dioxide Reduction ◽  
Catalyst Design ◽  
Recent Advances ◽  
Hierarchical Architectures ◽  
Second Coordination Sphere

The progress in CO2 reduction catalyst design was examined starting from simple metalloporphyrin structures and progressing to three-dimensional active architectures.

scholarly journals An amide-based second coordination sphere promotes the dimer pathway of Mn-catalyzed CO2-to-CO reduction at low overpotential

2021 ◽  
Vol 12 (13) ◽  
pp. 4779-4788
Author(s):  
Yong Yang ◽  
Mehmed Z. Ertem ◽  
Lele Duan
Keyword(s):  
Coordination Sphere ◽  
Bond Cleavage ◽  
Low Overpotential ◽  
Second Coordination Sphere ◽  
Co Reduction ◽  
Reduction Catalysts

The amide NH group decreases the overpotential of Mn-based CO2 reduction catalysts by promoting the dimer and protonation-first pathways in the presence of H2O and enhances the CO2 electroreduction activity by facilitating C–OH bond cleavage.

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