Ferrocene-containing non-interlocked molecular machines

2016 ◽  
Vol 52 (12) ◽  
pp. 2451-2464 ◽  
Author(s):  
Synøve Ø. Scottwell ◽  
James D. Crowley
Keyword(s):  
Ball Bearing ◽  
Molecular Machines ◽  
Redox Properties ◽  
Molecular Machine ◽  
Molecular Systems ◽  
Reversible Redox ◽  
Wide Range ◽  
Machine Systems

Ferrocene is chemically robust and readily functionalized which enables its facile incorporation into more complex molecular systems. This coupled with ferrocene's reversible redox properties and ability to function as a “molecular ball bearing” has led to the use of ferrocene as a component in wide range of non-interlocked synthetic molecular machine systems.

Strongly Coupled Redox-Linked Conformational Switching at the Active Site of the Non-Heme Iron-Dependent Dioxygenase, TauD

2019 ◽  
Author(s):  
Christopher John ◽  
Greg M. Swain ◽  
Robert P. Hausinger ◽  
Denis A. Proshlyakov
Keyword(s):  
Active Site ◽  
Structural Model ◽  
Heme Iron ◽  
Chemical Transformations ◽  
Experimental Conditions ◽  
Strongly Coupled ◽  
Non Heme Iron ◽  
Reversible Redox ◽  
Wide Range ◽  
Complex Structural

2-Oxoglutarate (2OG)-dependent dioxygenases catalyze C-H activation while performing a wide range of chemical transformations. In contrast to their heme analogues, non-heme iron centers afford greater structural flexibility with important implications for their diverse catalytic mechanisms. We characterize an <i>in situ</i> structural model of the putative transient ferric intermediate of 2OG:taurine dioxygenase (TauD) by using a combination of spectroelectrochemical and semi-empirical computational methods, demonstrating that the Fe (III/II) transition involves a substantial, fully reversible, redox-linked conformational change at the active site. This rearrangement alters the apparent redox potential of the active site between -127 mV for reduction of the ferric state and 171 mV for oxidation of the ferrous state of the 2OG-Fe-TauD complex. Structural perturbations exhibit limited sensitivity to mediator concentrations and potential pulse duration. Similar changes were observed in the Fe-TauD and taurine-2OG-Fe-TauD complexes, thus attributing the reorganization to the protein moiety rather than the cosubstrates. Redox difference infrared spectra indicate a reorganization of the protein backbone in addition to the involvement of carboxylate and histidine ligands. Quantitative modeling of the transient redox response using two alternative reaction schemes across a variety of experimental conditions strongly supports the proposal for intrinsic protein reorganization as the origin of the experimental observations.

scholarly journals Analysis of Dynamic Response of a Two Degrees of Freedom (2-DOF) Ball Bearing Nonlinear Model

2021 ◽  
Vol 11 (2) ◽  
pp. 787
Author(s):  
Bartłomiej Ambrożkiewicz ◽  
Grzegorz Litak ◽  
Anthimos Georgiadis ◽  
Nicolas Meier ◽  
Alexander Gassner
Keyword(s):  
Mathematical Model ◽  
Degrees Of Freedom ◽  
Ball Bearing ◽  
Hertzian Contact ◽  
Two Degrees Of Freedom ◽  
Wide Range ◽  
Shape Errors ◽  
Nonlinear Features ◽  
Fourier Transform Phase ◽  
Hertzian Contact Theory

Often the input values used in mathematical models for rolling bearings are in a wide range, i.e., very small values of deformation and damping are confronted with big values of stiffness in the governing equations, which leads to miscalculations. This paper presents a two degrees of freedom (2-DOF) dimensionless mathematical model for ball bearings describing a procedure, which helps to scale the problem and reveal the relationships between dimensionless terms and their influence on the system’s response. The derived mathematical model considers nonlinear features as stiffness, damping, and radial internal clearance referring to the Hertzian contact theory. Further, important features are also taken into account including an external load, the eccentricity of the shaft-bearing system, and shape errors on the raceway investigating variable dynamics of the ball bearing. Analysis of obtained responses with Fast Fourier Transform, phase plots, orbit plots, and recurrences provide a rich source of information about the dynamics of the system and it helped to find the transition between the periodic and chaotic response and how it affects the topology of RPs and recurrence quantificators.

Synthesis and Reversible Redox Properties of an Electron-Rich Polyferrocenylsilane withtert-Butyl Substituents on the Cyclopentadienyl Ligands

2006 ◽  
Vol 39 (11) ◽  
pp. 3720-3730 ◽  
Author(s):  
Georgeta Masson ◽  
Patrick Beyer ◽  
Paul W. Cyr ◽  
Alan J. Lough ◽  
Ian Manners
Keyword(s):  
Redox Properties ◽  
Cyclopentadienyl Ligands ◽  
Reversible Redox

scholarly journals Proton Pumping and Non-Pumping Terminal Respiratory Oxidases: Active Sites Intermediates of These Molecular Machines and Their Derivatives

2021 ◽  
Vol 22 (19) ◽  
pp. 10852
Author(s):  
Sergey A. Siletsky ◽  
Vitaliy B. Borisov
Keyword(s):  
Active Sites ◽  
Three Dimensional ◽  
Molecular Machines ◽  
Proton Pumping ◽  
Stress Reactions ◽  
Low Oxygen ◽  
Functional Studies ◽  
Wide Range ◽  
Regulatory Cascades ◽  
Respiratory Oxidases

Terminal respiratory oxidases are highly efficient molecular machines. These most important bioenergetic membrane enzymes transform the energy of chemical bonds released during the transfer of electrons along the respiratory chains of eukaryotes and prokaryotes from cytochromes or quinols to molecular oxygen into a transmembrane proton gradient. They participate in regulatory cascades and physiological anti-stress reactions in multicellular organisms. They also allow microorganisms to adapt to low-oxygen conditions, survive in chemically aggressive environments and acquire antibiotic resistance. To date, three-dimensional structures with atomic resolution of members of all major groups of terminal respiratory oxidases, heme-copper oxidases, and bd-type cytochromes, have been obtained. These groups of enzymes have different origins and a wide range of functional significance in cells. At the same time, all of them are united by a catalytic reaction of four-electron reduction in oxygen into water which proceeds without the formation and release of potentially dangerous ROS from active sites. The review analyzes recent structural and functional studies of oxygen reduction intermediates in the active sites of terminal respiratory oxidases, the features of catalytic cycles, and the properties of the active sites of these enzymes.

A TTFV–pyrene-based copolymer: synthesis, redox properties, and aggregation behaviour

RSC Advances ◽  
2015 ◽  
Vol 5 (30) ◽  
pp. 23952-23956 ◽  
Author(s):  
Eyad A. Younes ◽  
Kerry-Lynn M. Williams ◽  
Joshua C. Walsh ◽  
Celine M. Schneider ◽  
Graham J. Bodwell ◽  
...  
Keyword(s):  
Ph Value ◽  
Redox Properties ◽  
The Self ◽  
Redox Activity ◽  
Repeat Units ◽  
Aggregation Behaviour ◽  
Reversible Redox ◽  
Conjugated Copolymer ◽  
External Stimuli ◽  
Self Aggregation

A new π-conjugated copolymer containing tetrathiafulvalene vinylogue and pyrene repeat units was synthesized and exhibited reversible redox activity, while the self-aggregation behaviour in the solution phase was responsive to external stimuli such as solvent and pH value.

scholarly journals DNA Origami Nanomachines

Molecules ◽  
2018 ◽  
Vol 23 (7) ◽  
pp. 1766 ◽  
Author(s):  
Masayuki Endo ◽  
Hiroshi Sugiyama
Keyword(s):  
Dna Sequences ◽  
Molecular Motors ◽  
Molecular Machines ◽  
Dna Origami ◽  
Dna Nanostructures ◽  
Molecular Systems ◽  
Nanoscale Structures ◽  
Research Fields ◽  
Dna Strands ◽  
External Stimuli

DNA can assemble various molecules and nanomaterials in a programmed fashion and is a powerful tool in the nanotechnology and biology research fields. DNA also allows the construction of desired nanoscale structures via the design of DNA sequences. Structural nanotechnology, especially DNA origami, is widely used to design and create functionalized nanostructures and devices. In addition, DNA molecular machines have been created and are operated by specific DNA strands and external stimuli to perform linear, rotational, and reciprocating movements. Furthermore, complicated molecular systems have been created on DNA nanostructures by arranging multiple molecules and molecular machines precisely to mimic biological systems. Currently, DNA nanomachines, such as molecular motors, are operated on DNA nanostructures. Dynamic DNA nanostructures that have a mechanically controllable system have also been developed. In this review, we describe recent research on new DNA nanomachines and nanosystems that were built on designed DNA nanostructures.

A Critical Evaluation of the Redox Properties of Uranium, Neptunium and Plutonium Ions in Acidic Aqueous Solutions

1999 ◽  
Vol 71 (9) ◽  
pp. 1771-1807 ◽  
Author(s):  
Sorin Kihara ◽  
Zenko Yoshida ◽  
Hisao Aoyagi ◽  
Kohji Maeda ◽  
Osamu Shirai ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Redox Reactions ◽  
Critical Evaluation ◽  
Redox Properties ◽  
Redox Processes ◽  
Redox Potentials ◽  
Electrode Processes ◽  
Reversible Redox ◽  
Reduction Mechanisms ◽  
Current Potential

Standard redox potentials, E0s, and redox processes of U, Np and Pu ions in acidic aqueous solutions are reviewed and evaluated critically. The E0sof reversible redox processes, MO22+/MO2+ and M4+/M3+ (M: U, Np or Pu) adopted are those proposed mainly by Riglet et al. on the basis of the precise correction of formal potentials, E0's, according to the improved theoretical approach to estimate the activity coefficient. Electrode processes of the U, Np and Pu ions are discussed in terms of current-potential curves, measured so far by polarography, voltammetry or flow coulometry. Special attention is payed to the irreversible MO2+/M4+ reactions. Disproportionation reactions of MO2+ are also discussed. New substances are introduced as intermediates during reductions of MO2+ to M4+ or disproportionations of MO2+.CONTENTSIntroductionStandard redox potentials for uranium, neptunium and plutonium ions in acidic aqueous solutions2.1 Evaluation of E0 from E0' determined by electrochemical measurements2.2 Temperature dependence of E0Redox reactions of uranium, neptunium and plutonium in acidic aqueous solutions investigated by polarography or voltammetry3.1 Uranium3.2 Neptunium3.3 Plutonium3.4 Disproportionation of NpO2+, PuO2+, Np4+ and Pu4+3.5 Reduction of MO2+ and reduction intermediatesRedox reactions of uranium, neptunium and plutonium in acidic aqueous solutions investigated by flow coulometry4.1 Electrode processes of the uranium, neptunium and plutonium ions investigated by flow coulometry at the column electrode at the column electrode4.2 Disproportionation of MO2+ during the electrolysis by flow coulometry4.3 Reduction mechanisms of MO2+ (M = Np or Pu) and reduction intermediates investigated by flow coulometryConclusionsList of abbreviationsAppendixReferences

scholarly journals Driving Smart Molecular Systems by Artificial Molecular Machines

2020 ◽  
Vol 2 (5) ◽  
pp. 1900169 ◽  
Author(s):  
Zhao-Tao Shi ◽  
Qi Zhang ◽  
He Tian ◽  
Da-Hui Qu
Keyword(s):  
Molecular Machines ◽  
Molecular Systems

Recent Developments in Artificial Molecular-Machine–Based Active Nanomaterials and Nanosystems

MRS Bulletin ◽  
2008 ◽  
Vol 33 (3) ◽  
pp. 226-231 ◽  
Author(s):  
Tony Jun Huang
Keyword(s):  
Single Molecule ◽  
Interdisciplinary Research ◽  
Recent Progress ◽  
High Strain ◽  
Molecular Machines ◽  
High Impact ◽  
Molecular Machine ◽  
Mechanical Motion ◽  
Structures And Properties ◽  
Recent Developments

AbstractArtificial molecular machines capable of converting chemical, electrochemical, and photochemical energy into mechanical motion represent a high-impact, fast-growing field of interdisciplinary research. These molecular-scale systems utilize a “bottom-up” technology centered upon the design and manipulation of molecular assemblies and are potentially capable of delivering efficient actuation at length scales dramatically smaller than traditional microscale actuators. As actuation materials, molecular machines have many advantages, such as high strain (40%–60%), high force and energy densities, and the capability to maintain their actuation properties from the level of a single molecule to the macroscale. These advantages have inspired researchers to develop molecular-machine–based active nanomaterials and nanosystems, including electroactive and photoactive polymers. This article will discuss the structures and properties of artificial molecular machines, as well as review recent progress on efforts to move molecular machines from solution to surfaces to devices.

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