scholarly journals Probing the Electronic Structure of Spectator Oxo Ligands by 17O NMR Spectroscopy

2020 ◽  
Vol 74 (4) ◽  
pp. 225-231
Author(s):  
Christopher P. Gordon ◽  
Christophe Copéret
Keyword(s):  
Electronic Structure ◽  
Olefin Metathesis ◽  
Reaction Pathway ◽  
Binding Mode ◽  
Olefin Epoxidation ◽  
Nmr Parameters ◽  
The One ◽  
Oxo Ligand ◽  
17O Nmr Spectroscopy ◽  
Oxo Ligands

Spectator oxo ligands are ubiquitous in catalysis, in particular in olefin epoxidation and olefin metathesis. Here we use computationally derived 17O NMR parameters to probe the electronic structure of spectator oxo ligands in these two reactions. We show that 17O NMR parameters allow to distinguish between doubly-bonded and triply-bonded oxo ligands, giving detailed insights into the frontier molecular orbitals involved in the metaloxo bonds along the reaction pathway. On the one hand, our study shows that in olefin epoxidation catalysed by methyltrioxorhenium (MTO), the oxo ligand significantly changes its bonding mode upon formation of the oxygen-transferring Re-oxo-bisperoxo-species, changing its nature from a doubly bonded to a triply bonded oxo ligand. On the other hand, only minor changes in the binding mode are found along the olefin metathesis reaction pathway with Mo- and W-based oxo-alkylidene species, in which the oxo ligand behaves as a triply bonded ligand throughout the reaction. This finding contrasts earlier studies that proposed that the change of binding mode of the oxo ligand was key to metallacyclobutane formation.

Influence of nitrosyl coordination on the binding mode of quinaldate in selective ruthenium frameworks. Electronic structure and reactivity aspects

RSC Advances ◽  
2012 ◽  
Vol 2 (8) ◽  
pp. 3437 ◽  
Author(s):  
Abhishek Dutta Chowdhury ◽  
Prinaka De ◽  
Shaikh M. Mobin ◽  
Goutam Kumar Lahiri
Keyword(s):  
Electronic Structure ◽  
Binding Mode

scholarly journals Synthesis and electronic structure determination of uranium(vi) ligand radical complexes

2016 ◽  
Vol 45 (31) ◽  
pp. 12576-12586 ◽  
Author(s):  
Khrystyna Herasymchuk ◽  
Linus Chiang ◽  
Cassandra E. Hayes ◽  
Matthew L. Brown ◽  
Jeffrey S. Ovens ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Structure Determination ◽  
Salen Ligands ◽  
The One

Pentagonal bipyramidal uranyl (UO22+) complexes of salen ligands were prepared and the electronic structure of the one-electron oxidized species[1a–c]+were investigated in solution.

Switching the Oxygen Reduction Reaction Pathway via Tailoring the Electronic Structure of FeN4/C Catalysts

ACS Catalysis ◽  
2021 ◽  
pp. 13020-13027
Author(s):  
Yanping Zhu ◽  
Jiejie Li ◽  
Yubin Chen ◽  
Jian Zou ◽  
Qingqing Cheng ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Reaction Pathway ◽  
Reduction Reaction

Protein environment affects the water–tryptophan binding mode. MD, QM/MM, and NMR studies of engrailed homeodomain mutants

2018 ◽  
Vol 20 (18) ◽  
pp. 12664-12677 ◽  
Author(s):  
Nad'a Špačková ◽  
Zuzana Trošanová ◽  
Filip Šebesta ◽  
Séverine Jansen ◽  
Jaroslav V. Burda ◽  
...  
Keyword(s):  
Amino Acids ◽  
Lone Pair ◽  
Binding Mode ◽  
The Other ◽  
Water Molecules ◽  
Interaction Type ◽  
Nmr Studies ◽  
Engrailed Homeodomain ◽  
The One ◽  
Protein Environment

Water molecules can interact with the π-face of tryptophan either forming an O–H⋯π hydrogen bond or by a lone-pair⋯π interaction. Surrounding amino acids can favor the one or the other interaction type.

Properties of the one-electron oxidized copper(II) salen-type complexes: relationship between electronic structures and reactivities

2014 ◽  
Vol 86 (2) ◽  
pp. 163-172 ◽  
Author(s):  
Yuichi Shimazaki
Keyword(s):  
Electronic Structure ◽  
Electronic Structures ◽  
Functional Model ◽  
Phenoxyl Radical ◽  
Catalytic Cycle ◽  
Model Systems ◽  
Galactose Oxidase ◽  
Primary Alcohols ◽  
Radical Species ◽  
The One

Abstract The Cu(II)-phenoxyl radical formed during the catalytic cycle of galactose oxidase (GO) attracted much attention, and the structures and properties of a number of metal-phenoxyl radical complexes have been studied. Some of the functional model systems of GO reported previously have shown that the Cu complexes oxidize primary alcohols to aldehydes and that the Cu(II)-phenoxyl radical species is formed in the catalytic cycle. Many Cu(II)-phenoxyl radical species have been produced by one-electron oxidation of the Cu(II)-phenolate complexes. On the other hand, one-electron oxidation of a Cu(II)-phenolate complex has the possibility to give different electronic structures, one of which is the Cu(III)-phenolate. From these points of view, this micro review is focused on the one-electron oxidized square-planar Cu(II) complexes of the salen-type ligands. Introduction of substituents into the phenolate moieties and conversion from a 5- to a 6-membered chelate backbone alter the electronic structure of the one-electron oxidized Cu(II) complexes and give rise to a different reactivity of benzyl alcohol oxidation. The relationship between the electronic structure and the reactivity is herein discussed.

scholarly journals Discovery of a hidden transient state in all bromodomain families

2021 ◽  
Vol 118 (4) ◽  
pp. e2017427118
Author(s):  
Lluís Raich ◽  
Katharina Meier ◽  
Judith Günther ◽  
Clara D. Christ ◽  
Frank Noé ◽  
...  
Keyword(s):  
Posttranslational Modifications ◽  
Rational Design ◽  
General Structure ◽  
Transient State ◽  
Structural Data ◽  
Binding Mode ◽  
Dynamical Features ◽  
The One ◽  
Markov State Modeling ◽  
Dynamics Simulations

Bromodomains (BDs) are small protein modules that interact with acetylated marks in histones. These posttranslational modifications are pivotal to regulate gene expression, making BDs promising targets to treat several diseases. While the general structure of BDs is well known, their dynamical features and their interplay with other macromolecules are poorly understood, hampering the rational design of potent and selective inhibitors. Here, we combine extensive molecular dynamics simulations, Markov state modeling, and available structural data to reveal a transiently formed state that is conserved across all BD families. It involves the breaking of two backbone hydrogen bonds that anchor the ZA-loop with the αA helix, opening a cryptic pocket that partially occludes the one associated to histone binding. By analyzing more than 1,900 experimental structures, we unveil just two adopting the hidden state, explaining why it has been previously unnoticed and providing direct structural evidence for its existence. Our results suggest that this state is an allosteric regulatory switch for BDs, potentially related to a recently unveiled BD-DNA–binding mode.

scholarly journals catena-Poly[barium(II)-μ2-(dimethyl sulfoxide)-κ2 O:O-bis(μ2-2,4,6-trinitrophenolato-κ4 O 2,O 1:O 1,O 6)]

IUCrData ◽  
2020 ◽  
Vol 5 (11) ◽  
Author(s):  
Bikshandarkoil R. Srinivasan ◽  
Neha U. Parsekar ◽  
Kedar U. Narvekar
Keyword(s):  
Coordination Polymer ◽  
Oxygen Atom ◽  
Dimethyl Sulfoxide ◽  
Point Group ◽  
Binding Mode ◽  
Group Symmetry ◽  
Site Symmetry ◽  
Cation Site ◽  
A Chain ◽  
The One

The asymmetric unit of the title barium coordination polymer, [Ba(C6H2N3O7)2(C2H6OS)] n , consists of a barium cation (site symmetry m) and a dimethyl sulfoxide (DMSO) ligand (point group symmetry m) and a 2,4,6-trinitrophenolate anion located in general positions. The S atom and the methyl group of DMSO are disordered over two sets of sites. The DMSO ligand bridges a pair of BaII atoms resulting in a chain extending parallel to the a axis. The unique 2,4,6-trinitrophenolate anion also bridges a pair of BaII ions via the phenolic oxygen atom, with each BaII being additionally bonded to an oxygen atom of an adjacent nitro group. The μ 2-monoatomic bridging binding mode of both types of ligands results in the formation of an infinite chain of face-sharing {BaO10} polyhedra flanked by the remaining parts of the 2,4,6-trinitrophenolato and DMSO ligands. In the one-dimensional coordination polymer, parallel chains are interlinked with the aid of C—H...O hydrogen bonds.

scholarly journals Discovery of a hidden transient state in all bromodomain families

2020 ◽  
Author(s):  
Lluís Raich ◽  
Katharina Meier ◽  
Judith Günther ◽  
Clara D. Christ ◽  
Frank Noé ◽  
...  
Keyword(s):  
Rational Design ◽  
General Structure ◽  
Transient State ◽  
Structural Data ◽  
Binding Mode ◽  
Post Translational Modifications ◽  
Dynamical Features ◽  
The One ◽  
Markov State Modeling ◽  
Dynamics Simulations

ABSTRACTBromodomains (BDs) are small protein modules that interact with acetylated marks in histones. These post-translational modifications are pivotal to regulate gene expression, making BDs promising targets to treat several diseases. While the general structure of BDs is well known, their dynamical features and their interplay with other macromolecules are poorly understood, hampering the rational design of potent and selective inhibitors. Here we combine extensive molecular dynamics simulations, Markov state modeling and structural data to reveal a novel and transiently formed state that is conserved across all BD families. It involves the breaking of two backbone hydrogen bonds that anchor the ZA-loop with the αA helix, opening a cryptic pocket that partially occludes the one associated with histone binding. Our results suggest that this novel state is an allosteric regulatory switch for BDs, potentially related to a recently unveiled BD-DNA binding mode.

scholarly journals Dinitrosylmolybdenum Complexes with Anion Ligands Coordinating by Oxygen Atoms. Synthesis, Electronic Structure and Olefin Metathesis Activity of Carboxylato-Dinitrosyl-Molybdenum Complexes

1992 ◽  
Vol 47 (10) ◽  
pp. 1469-1476 ◽  
Author(s):  
Antoni Keller ◽  
Ludmiła Szterenberg
Keyword(s):  
Electronic Structure ◽  
Catalytic Activity ◽  
Excited States ◽  
Olefin Metathesis ◽  
Spectroscopic Properties ◽  
Metathesis Reaction ◽  
Molybdenum Complexes ◽  
H Nmr ◽  
Spectroscopic Investigations ◽  
Oxygen Atoms

The new carboxylato-dinitrosyl-molybdenum complexes of the formula: [Mo(NO)2(O2CMe)2] • MeOH, Na2[Mo(NO)2(O2CMe)4] and Mo(NO)2(O2CPh)2 have been synthesized. Their structure was resolved on the basis of spectroscopic investigations (1H NMR, IR, UV-VIS). Catalytic activity of these complexes in olefin metathesis reaction was also examined.The electronic structure of dinitrosyl-molybdenum complexes with ligands coordinating by oxygen atoms was calculated for the example of the di- and tetra-acetato-dinitrosyl-molybdenum complexes using the Fenske-Hall and INDO methods. To interpret the spectroscopic properties (UV-VIS) within the method of interaction configuration, the electronic structure of the excited states was calculated.

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