Generation and Coupling of[Mn(dmpe)2(CCR)(CC)]. Radicals Producing Redox-Active C4-Bridged Rigid-Rod Complexes

2003 ◽  
Vol 9 (24) ◽  
pp. 6192-6206 ◽  
Author(s):  
Francisco J. Fernández ◽  
Koushik Venkatesan ◽  
Olivier Blacque ◽  
Montserrat Alfonso ◽  
Helmut W. Schmalle ◽  
...  
Keyword(s):  
Redox Active ◽  
Rigid Rod

Synthesis and Characterization of Redox-Active C4-Bridged Rigid-Rod Complexes with Acetylide-Substituted Manganese End Groups

2005 ◽  
Vol 24 (12) ◽  
pp. 2834-2847 ◽  
Author(s):  
Koushik Venkatesan ◽  
Thomas Fox ◽  
Helmut W. Schmalle ◽  
Heinz Berke
Keyword(s):  
Synthesis And Characterization ◽  
Redox Active ◽  
End Groups ◽  
Rigid Rod

A facile and new type of route to the redox-active rigid-rod complex [{Mn(dmpe)2(CCH)}2(μ-C4)][PF6] via Mn–C2˙ radical coupling

2001 ◽  
pp. 1266-1267 ◽  
Author(s):  
Francisco J. Fernández ◽  
Olivier Blacque ◽  
Montserrat Alfonso ◽  
Heinz Berke
Keyword(s):  
Radical Coupling ◽  
Redox Active ◽  
New Type ◽  
Rigid Rod

scholarly journals Ferrocenylethynyl - a versatile platform for new molecules to novel materials

2014 ◽  
Vol 19 (1) ◽  
pp. 15
Author(s):  
Hakikulla H. Shah ◽  
Rayya A. Al-Belushi ◽  
Muhammad S. Khan
Keyword(s):  
Material Properties ◽  
Optical Materials ◽  
Chelating Agents ◽  
Functional Materials ◽  
Synthetic Methods ◽  
Electron Delocalization ◽  
Redox Active ◽  
Wide Range ◽  
Rigid Rod ◽  
Open Issues

Ferrocenylethynyl is a key starting material for the synthesis of fascinating new molecules and novel functional materials. It combines the robust and redox-active ferrocene moiety with the rigid-rod ethynyl unit. The ferrocene center provides chemically and electrochemically switchable material properties whereas the ethynyl backbone facilitates electron delocalization along the molecule, yielding materials with the potential for a wide range of applications from sensors to bio-organometallics and pharmaceuticals, from catalysts to nonlinear optical materials, and from fuel additives to chelating agents. However, lifetime performances and costs still need to be optimized to make ferrocenylethynyl-based materials commercially competitive. Efficient synthetic methods are already in place which could play a key role in the progress of these materials. This review discusses the main approaches adopted in the synthesis of ferrocenylethynyl-based molecules and materials. Representative examples of each method are reported, highlighting its significant achievements together with the open issues and challenges to be faced by future researchers in this area. 

Morphology of High-Performance Rigid-Rod Polymer Fibers and Molecular Composites

1989 ◽  
Vol 47 ◽  
pp. 338-339
Author(s):  
W.W. Adams ◽  
S. J. Krause
Keyword(s):  
Tensile Strength ◽  
High Performance ◽  
Liquid Crystalline ◽  
Molecular Level ◽  
Synergistic Effects ◽  
Tensile Modulus ◽  
Commercial Development ◽  
The Matrix ◽  
Molecular Composites ◽  
Rigid Rod

Rigid-rod polymers such as PBO, poly(paraphenylene benzobisoxazole), Figure 1a, are now in commercial development for use as high-performance fibers and for reinforcement at the molecular level in molecular composites. Spinning of liquid crystalline polyphosphoric acid solutions of PBO, followed by washing, drying, and tension heat treatment produces fibers which have the following properties: density of 1.59 g/cm3; tensile strength of 820 kpsi; tensile modulus of 52 Mpsi; compressive strength of 50 kpsi; they are electrically insulating; they do not absorb moisture; and they are insensitive to radiation, including ultraviolet. Since the chain modulus of PBO is estimated to be 730 GPa, the high stiffness also affords the opportunity to reinforce a flexible coil polymer at the molecular level, in analogy to a chopped fiber reinforced composite. The objectives of the molecular composite concept are to eliminate the thermal expansion coefficient mismatch between the fiber and the matrix, as occurs in conventional composites, to eliminate the interface between the fiber and the matrix, and, hopefully, to obtain synergistic effects from the exceptional stiffness of the rigid-rod molecule. These expectations have been confirmed in the case of blending rigid-rod PBZT, poly(paraphenylene benzobisthiazole), Figure 1b, with stiff-chain ABPBI, poly 2,5(6) benzimidazole, Fig. 1c A film with 30% PBZT/70% ABPBI had tensile strength 190 kpsi and tensile modulus of 13 Mpsi when solution spun from a 3% methane sulfonic acid solution into a film. The modulus, as predicted by rule of mixtures, for a film with this composition and with planar isotropic orientation, should be 16 Mpsi. The experimental value is 80% of the theoretical value indicating that the concept of a molecular composite is valid.

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.

Alignment of Rigid-Rod Polypeptide Chains by Solvent Quenching

2003 ◽  
Vol 771 ◽  
Author(s):  
Yuli Wang ◽  
Ying Chih Chang
Keyword(s):  
Tilt Angle ◽  
Rigid Rod ◽  
Polypeptide Chains ◽  
Poor Solvent

AbstractWe introduce a simple “solvent quenching” approach to align the rigid-rod à-helical poly(α-benzyl-L-glutamate) (PBLG) chains in the surface-grafted monolayer. By sequentially treating with a good solvent and a poor solvent, a unidirectionally aligned PBLG monolayer with an average tilt angle as small as 3° is obtained.

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>

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