A potassium-selective sulfide-linked redox-active ferrocene ionophore that exhibits extraordinary electrochemical recognition behaviour

1993 ◽  
pp. 1735 ◽  
Author(s):  
Paul D. Beer ◽  
Jonathan P. Danks ◽  
Dusan Hesek ◽  
Jerome F. McAleer
Keyword(s):  
Redox Active ◽  
Electrochemical Recognition

Electrochemical recognition of group 1 and 2 metal cations by redox-active ionophores

1994 ◽  
Vol 225 (1-2) ◽  
pp. 137-144 ◽  
Author(s):  
Paul D. Beer ◽  
Zheng Chen ◽  
Michael G.B. Drew ◽  
Alexandra J. Pilgrim
Keyword(s):  
Metal Cations ◽  
Redox Active ◽  
Electrochemical Recognition ◽  
Group 1

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>

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