Reactions of dicobalt octacarbonyl with dinucleating and mononucleating bis(imino)pyridine ligands

2018 ◽  
Vol 47 (43) ◽  
pp. 15353-15363 ◽  
Author(s):  
Ryan L. Hollingsworth ◽  
Jeffrey W. Beattie ◽  
Amanda Grass ◽  
Philip D. Martin ◽  
Stanislav Groysman ◽  
...  
Keyword(s):  
Pyridine Ligands ◽  
Dicobalt Octacarbonyl ◽  
Redox Active

Reactivity of dicobalt octacarbonyl with dinucleating and mononucleating redox-active bis(imino)pyridines is investigated.

Reversible C–C Bond Formation between Redox-Active Pyridine Ligands in Iron Complexes

2012 ◽  
Vol 134 (50) ◽  
pp. 20352-20364 ◽  
Author(s):  
Thomas R. Dugan ◽  
Eckhard Bill ◽  
K. Cory MacLeod ◽  
Gemma J. Christian ◽  
Ryan E. Cowley ◽  
...  
Keyword(s):  
Bond Formation ◽  
Iron Complexes ◽  
Pyridine Ligands ◽  
Redox Active

scholarly journals A DFT Study on the Redox Active Behavior of Carbene and Pyridine Ligands in the Oxidative and Reductive Quenching Cycles of Ruthenium Photoredox Catalysts

Catalysts ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 80
Author(s):  
Edinson Medina ◽  
Balazs Pinter
Keyword(s):  
Density Functional ◽  
Interaction Analysis ◽  
Photon Absorption ◽  
Redox Potentials ◽  
State Reduction ◽  
Covalent Interaction ◽  
Reduction Potentials ◽  
Pyridine Ligands ◽  
Redox Active ◽  
Characteristic Features

In this study, a detailed look at the electronic structure changes induced by photon absorption and of the succeeding redox events of the oxidative and reductive quenching cycles of ruthenium–carbene and ruthenium–pyridine photoredox catalysts is provided through an arsenal of density functional theory-based techniques including electron density difference Δρ(r) maps, spin-density distributions, and the non-covalent interaction analysis. We introduced an efficient computational protocol to obtain accurate equilibrium structures and ground-state reduction potentials for these types of complexes, substantiated via a direct comparison to empirical X-ray structures and cyclic voltammetry measurements, respectively. Moreover, we demonstrated the utility of a hitherto unexplored approach to compute excited-state redox potentials based on the Gibbs free energy of the triplet metal-to-ligand charge transfer state (3MLCT). The analyzed Δρ(r) maps revealed the characteristic features of, for example, metal- and ligand-centered reductions and oxidations in both ground and excited states and MLCT processes, disclosing the active participation of carbene ligands in the redox events of homoleptic systems. Beyond analyzing ligand–ligand non-covalent interactions and redox-active behaviors of carbene and pyridine ligands side by side, the effect of such groups on the kinetics of 3MLCT to 3MC transition was scrutinized.

scholarly journals Synthesis, Characterization and Antimicrobial Properties of [Cu2(μ-O2CC9H19)4(4-CNpy)2]

2021 ◽  
Vol 33 (2) ◽  
pp. 453-458
Author(s):  
Nirupamjit Sarmah ◽  
Sukanya Baruah ◽  
Anup Malakar ◽  
Monideepa Chakrabortty ◽  
Bhabatosh Banik ◽  
...  
Keyword(s):  
Complex I ◽  
Antimicrobial Properties ◽  
Bacterial Strains ◽  
Pyridyl Nitrogen ◽  
Pyridine Ligands ◽  
Pyramidal Geometry ◽  
Redox Active ◽  
Physico Chemical ◽  
Vis Spectroscopy ◽  
Active Nature

Reports on the isolation and crystallographic characterization of metal carboxylates having long alkyl chains are relatively rare. Herein, a dinuclear copper(II) tetracaprate (i.e. tetradecanoate) complex, [Cu2(μ-O2CC9H19)4(4-CNpy)2] (I), where 4-CNpy = 4-cyanopyridine is reported. The complex has been synthesized by a facile method and characterized by various physico-chemical techniques such as IR and UV-vis spectroscopy, magnetic susceptibility measurement and single crystal X-ray diffraction. The structure is dimeric with the familiar paddle-wheel geometry, which was originally observed in the structure of copper(II) acetate monohydrate. In the dimeric structure, both copper(II) centres display distorted square pyramidal geometry. The substituted pyridine ligands occupy the apical positions through the pyridyl nitrogen atoms. Complex I has been tested for antimicrobial behaviour against a few bacterial strains. Owing to the redox-active nature of copper, complex I shows considerable promise as an antimicrobial agent.

scholarly journals An unknown component of a selective and mild oxidant: structure and oxidative ability of a double salt-type complex having κ1O-coordinated permanganate anions and three- and four-fold coordinated silver cations

RSC Advances ◽  
2019 ◽  
Vol 9 (49) ◽  
pp. 28387-28398 ◽  
Author(s):  
Gréta Bettina Kovács ◽  
Nóra V. May ◽  
Petra Alexandra Bombicz ◽  
Szilvia Klébert ◽  
Péter Németh ◽  
...  
Keyword(s):  
Low Temperature ◽  
Redox Reaction ◽  
Solid Phase ◽  
Silver Ions ◽  
Double Salt ◽  
Pyridine Ligands ◽  
Type Complex ◽  
Redox Active ◽  
Unknown Component ◽  
Silver Cations

A compound having redox-active permanganate and complexed silver ions with reducing pyridine ligands is used as a mild organic and as a precursor for nanocatalyst synthesis in a low-temperature solid-phase quasi-intramolecular redox reaction.

Common modifications of selenocysteine in selenoproteins

2019 ◽  
Vol 64 (1) ◽  
pp. 45-53 ◽  
Author(s):  
Elias S.J. Arnér
Keyword(s):  
Amino Acids ◽  
Covalent Binding ◽  
Physicochemical Characteristics ◽  
Redox Active

Abstract Selenocysteine (Sec), the sulfur-to-selenium substituted variant of cysteine (Cys), is the defining entity of selenoproteins. These are naturally expressed in many diverse organisms and constitute a unique class of proteins. As a result of the physicochemical characteristics of selenium when compared with sulfur, Sec is typically more reactive than Cys while participating in similar reactions, and there are also some qualitative differences in the reactivities between the two amino acids. This minireview discusses the types of modifications of Sec in selenoproteins that have thus far been experimentally validated. These modifications include direct covalent binding through the Se atom of Sec to other chalcogen atoms (S, O and Se) as present in redox active molecular motifs, derivatization of Sec via the direct covalent binding to non-chalcogen elements (Ni, Mb, N, Au and C), and the loss of Se from Sec resulting in formation of dehydroalanine. To understand the nature of these Sec modifications is crucial for an understanding of selenoprotein reactivities in biological, physiological and pathophysiological contexts.

On the Crystal Chemistry of Inorganic Nitrides: Crystal-Chemical Parameters and Opportunities in the Exploration of Their Compositional Space

2020 ◽  
Author(s):  
Olivier Charles Gagné
Keyword(s):  
Functional Properties ◽  
A Priori ◽  
Lone Pair ◽  
Length Variation ◽  
Electronic Effects ◽  
Statistical Knowledge ◽  
Redox Active ◽  
Multiply Bonded ◽  
Jahn Teller ◽  
Compositional Space

The scarcity of nitrogen in Earth’s crust, combined with challenging synthesis, have made inorganic nitrides a relatively-unexplored class of compounds compared to their naturally-abundant oxide counterparts. To facilitate exploration of their compositional space via <i>a priori</i> modeling, and to help <i>a posteriori</i> structure verification not limited to inferring the oxidation state of redox-active cations, we derive a suite of bond-valence parameters and Lewis-acid strength values for 76 cations observed bonding to N<sup>3-</sup>, and further outline a baseline statistical knowledge of bond lengths for these compounds. We examine structural and electronic effects responsible for the functional properties and anomalous bonding behavior of inorganic nitrides, and identify promising venues for exploring uncharted compositional spaces beyond the reach of high-throughput computational methods. We find that many mechanisms of bond-length variation ubiquitous to oxide and oxysalt compounds (e.g., lone-pair stereoactivity, the Jahn-Teller and pseudo Jahn-Teller effects) are similarly pervasive in inorganic nitrides, and are occasionally observed to result in greater distortion magnitude than their oxide counterparts. We identify inorganic nitrides with multiply-bonded metal ions as a promising venue in heterogeneous catalysis, e.g. in the development of a post-Haber-Bosch process proceeding at milder reaction conditions, thus representing further opportunity in the thriving exploration of the functional properties of this emerging class of materials.<br>

Energetic Control of Redox-Active Polymers Towards Safe Organic Bioelectronic Materials

2019 ◽  
Author(s):  
Alexander Giovannitti ◽  
Reem B. Rashid ◽  
Quentin Thiburce ◽  
Bryan D. Paulsen ◽  
Camila Cendra ◽  
...  
Keyword(s):  
Molecular Oxygen ◽  
Organic Semiconductors ◽  
Side Reaction ◽  
Semiconducting Polymers ◽  
Side Reactions ◽  
Redox Active ◽  
Donor Acceptor ◽  
Electrochemical Devices ◽  
Biological Environment ◽  
Device Operation

<p>Avoiding faradaic side reactions during the operation of electrochemical devices is important to enhance the device stability, to achieve low power consumption, and to prevent the formation of reactive side‑products. This is particularly important for bioelectronic devices which are designed to operate in biological systems. While redox‑active materials based on conducting and semiconducting polymers represent an exciting class of materials for bioelectronic devices, they are susceptible to electrochemical side‑reactions with molecular oxygen during device operation. We show that this electrochemical side reaction yields hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>), a reactive side‑product, which may be harmful to the local biological environment and may also accelerate device degradation. We report a design strategy for the development of redox-active organic semiconductors based on donor-acceptor copolymers that prevent the formation of H<sub>2</sub>O<sub>2</sub> during device operation. This study elucidates the previously overlooked side-reactions between redox-active conjugated polymers and molecular oxygen in electrochemical devices for bioelectronics, which is critical for the operation of electrolyte‑gated devices in application-relevant environments.</p>

Theoretical Exploration of 2,2’-Bipyridines as Electro-Active Compounds in Flow Batteries

2019 ◽  
Author(s):  
Mariano Sánchez-Castellanos ◽  
Martha M. Flores-Leonar ◽  
Zaahel Mata-Pinzón ◽  
Humberto G. Laguna ◽  
Karl García-Ruiz ◽  
...  
Keyword(s):  
Redox Potential ◽  
Active Material ◽  
Chemical Properties ◽  
Small Subset ◽  
Solubility In Water ◽  
Protonation Reaction ◽  
Redox Active ◽  
Physico Chemical ◽  
Pka Value ◽  
Flow Batteries

Compounds from the 2,2’-bipyridine molecular family were investigated for use as redox-active materials in organic flow batteries. For 156 2,2’-bipyridine derivatives reported in the academic literature, we calculated the redox potential, the pKa for the first protonation reaction, and the solubility in aqueous solutions. Using experimental data on a small subset of derivatives, we were able to calibrate our calculations. We find that functionalization with electron-withdrawing groups leads to an increase of the redox potential and to an increase of the molecular acidity (as expressed in a reduction of the pKa value for the first protonation step). Furthermore, calculations of solubility in water indicate that some of the studied derivatives have adequate solubility for flow battery applications. Based on an analysis of the physico-chemical properties of the 156 studied compounds, we down-select five molecules with carbonyl- and nitro-based functional groups, whose parameters are especially promising for potential application as negative redox-active material inorganic flow batteries.

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