scholarly journals Robust thermoelastic microactuator based on an organic molecular crystal

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Yulong Duan ◽  
Sergey Semin ◽  
Paul Tinnemans ◽  
Herma Cuppen ◽  
Jialiang Xu ◽  
...  
Keyword(s):  
Structural Phase ◽  
Artificial Muscles ◽  
Molecular Configuration ◽  
Dynamic Simulations ◽  
Thermally Induced ◽  
Molecular Actuators ◽  
Strong Shear ◽  
Phenyl Rings ◽  
External Stimuli ◽  
Nucleation And Growth Mechanism

Abstract Mechanically responsive molecular crystals that reversibly change shape triggered by external stimuli are invaluable for the design of actuators for soft robotics, artificial muscles and microfluidic devices. However, their strong deformations usually lead to their destruction. We report a fluorenone derivative (4-DBpFO) showing a strong shear deformation upon heating due to a structural phase transition which is reproducible after more than hundred heating/cooling cycles. Molecular dynamic simulations show that the transition occurs through a nucleation-and-growth mechanism, triggered by thermally induced rotations of the phenyl rings, leading to a rearrangement of the molecular configuration. The applicability as actuator is demonstrated by displacing a micron-sized glass bead over a large distance, delivering a kinetic energy of more than 65 pJ, corresponding to a work density of 270 J kg−1. This material can serve as a prototype structure to direct the development of new types of robust molecular actuators.

scholarly journals Recent Progress in the Synthesis and Characterization of Diarylethene-based MOFs

2014 ◽  
Vol 70 (a1) ◽  
pp. C1223-C1223
Author(s):  
Jason Benedict ◽  
Ian Walton ◽  
Dan Patel ◽  
Jordan Cox
Keyword(s):  
Chemical Properties ◽  
Building Blocks ◽  
Synthesis And Characterization ◽  
Next Generation ◽  
Design Synthesis ◽  
Thermally Induced ◽  
Potential Applications ◽  
External Stimuli ◽  
Physical And Chemical

Metal-organic Frameworks (MOFs) remain an extremely active area of research given the wide variety of potential applications and the enormous diversity of structures that can be created from their constituent building blocks. While MOFs are typically employed as passive materials, next-generation materials will exhibit structural and/or electronic changes in response to applied external stimuli including light, charge, and pH. Herein we present recent results in which advanced photochromic diarylethenes are combined with MOFs through covalent and non-covalent methods to create photo-responsive permanently porous crystalline materials. This presentation will describe the design, synthesis, and characterization of next-generation photo-switchable diarylethene based ligands which are subsequently used to photo-responsive MOFs. These UBMOF crystals are, by design, isostructural with previously reported non-photoresponsive frameworks which enables a systematic comparison of their physical and chemical properties. While the photoswitching of the isolated ligand in solution is fully reversible, the cycloreversion reaction is suppressed in the UBMOF single crystalline phase. Spectroscopic evidence for thermally induced cycloreversion will be presented, as well as a detailed analysis addressing the limits of X-ray diffraction techniques applied to these systems.

scholarly journals Stimuli-responsive polymers and their applications

2017 ◽  
Vol 8 (1) ◽  
pp. 127-143 ◽  
Author(s):  
Menglian Wei ◽  
Yongfeng Gao ◽  
Xue Li ◽  
Michael J. Serpe
Keyword(s):  
Drug Delivery ◽  
Physical Properties ◽  
Artificial Muscles ◽  
Stimuli Responsive ◽  
Stimuli Responsive Polymers ◽  
Responsive Polymers ◽  
Responsive Polymer ◽  
External Stimuli

Responsive polymer-based materials are capable of altering their chemical and/or physical properties upon exposure to external stimuli. This review highlights their use for sensing and biosensing, drug delivery, and artificial muscles/actuators.

Size-dependent structural phase transition of face-centered-cubic metal nanowires

2007 ◽  
Vol 22 (5) ◽  
pp. 1299-1305 ◽  
Author(s):  
F. Ma ◽  
K.W. Xu
Keyword(s):  
Surface Energy ◽  
Metastable Phase ◽  
Structural Phase ◽  
Intrinsic Stress ◽  
Metal Nanowires ◽  
Face Centered Cubic ◽  
Phase Transform ◽  
Face Centered ◽  
Epitaxial Bain Paths ◽  
External Stimuli

Taking Au as an example, we have investigated the epitaxial bain paths of 〈001〉 oriented face-centered-cubic metal nanowires. It demonstrates that there are one stable and one metastable phase, having the lattice constant ratio c/a of about 0.6 and 1.0, respectively. Even without any external stimuli, the surface-tension-induced intrinsic stress in the interior may drive the nanowires to phase transform spontaneously for surface-energy minimization. However, this structural transition depends on the feature sizes of the nanowires. Specifically, only when the cross-section areas are reduced to 4.147 nm2 or so can the surface energy and the intrinsic stress satisfy the thermodynamic and kinetic conditions simultaneously.

scholarly journals A Boron-Transfer Mechanism Mediating the Thermally Induced Revival of Frustrated Carbene−Borane Pairs from their Shelf-Stable Adducts

2021 ◽  
Author(s):  
Yoichi Hoshimoto ◽  
Mahiro Sakuraba ◽  
Takuya Kinoshita ◽  
Masaki Ohbo ◽  
Manussada Ratanasak ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Carbon Atom ◽  
Oxygen Atom ◽  
Phosphine Oxide ◽  
Theoretical Studies ◽  
Stimuli Responsive ◽  
Thermally Induced ◽  
Shelf Stable ◽  
External Stimuli ◽  
Experimental And Theoretical Studies

Combined experimental and theoretical studies allowed clarifying the reaction mechanism for the revival of frustrated carbene−borane pairs from external-stimuli-responsive classical Lewis adducts comprised of N-phosphine oxide-substituted imidazolylidenes and triarylboranes. A borane-transfer process from the carbene carbon atom to the N-phosphinoyl oxygen atom was identified as the rate-determining event for the regeneration of the FLP species, eventually enabling the heterolytic cleavage of H2.<br>

scholarly journals A Soft On/Off Switch Based on the Electrochemically Reversible H-J Interconversion of a Floating Porphyrin Membrane

2021 ◽  
Author(s):  
Andrés F. Molina-Osorio ◽  
Sho Yamamoto ◽  
Alonso Gamero-Quijano ◽  
Hirohisa Nagatani ◽  
Micheal D. Scanlon
Keyword(s):  
Self Assembly ◽  
Electrical Potential ◽  
Electrolyte Solutions ◽  
Structural Rearrangement ◽  
Organic Electrolyte ◽  
Molecular Configuration ◽  
Additional Control ◽  
The Individual ◽  
External Stimuli

<p>Soft molecular assemblies that respond reversibly to external stimuli are attractive materials as on/off switches, in optoelectronic, memory and sensor technologies. In this article, we present the reversible structural rearrangement of a soft porphyrin membrane under an electrical potential stimulus in the absence of solid-state architectures. The free-floating porphyrin membrane lies at the interface between immiscible aqueous and organic electrolyte solutions and is formed through interfacial self-assembly of zinc(II) meso-tetrakis(4-carboxyphenyl)porphyrins (ZnPor). A potential difference between the two immiscible electrolyte solutions induces the intercalation of bis(triphenylphosphoranylidene)ammonium cations from the organic electrolyte that exchange with protons in the porphyrin membrane. In situ UV/vis absorbance spectroscopy shows that this ionic intercalation and exchange induces a structural interconversion of the individual porphyrin molecules in the membrane from an H- to a J-type molecular configuration. These structural rearrangements are reversible over 30 potential cycles. In situ polarisation-modulation fluorescence spectroscopy further provides clear evidence of structural interconversion of the porphyrin membrane, as intercalation of the organic electrolyte cations significantly affects the latter’s emissive properties. By adjusting the pH of the aqueous phase, additional control of the electrochemically reversible structural interconversion can be achieved, with total suppression at pH 3.<br></p>

scholarly journals Photosalient Effect: Dramatic conversion of light into mechanical motion

2014 ◽  
Vol 70 (a1) ◽  
pp. C1224-C1224
Author(s):  
Subash Sahoo ◽  
Pance Naumov
Keyword(s):  
Single Crystals ◽  
Flexible Electronics ◽  
Mechanical Response ◽  
Mechanical Energy ◽  
Small Scale ◽  
Molecular Rotor ◽  
Mechanical Motion ◽  
Molecular Actuators ◽  
Liquid Crystal Elastomers ◽  
External Stimuli

Materials showing mechanical response in presence of external stimuli are of relevance for the design of nanoscale actuating devices for a variety of small-scale applications including actuators, flexible electronics, artificial muscles, and others. In recent years, molecular actuators[1] (molecular rotor, elevator, etc.) and several macroscopic systems based on liquid-crystal elastomers, gels, and other polymers[2] have been developed. The most recent efforts are aimed at achieving rapid, reversible, maximum and fatigueless response with single crystals which display optimum coupling between light and the mechanical energy. When exposed to light, certain single crystals can jump up to thousands times their own size. The term "photosalient" was introduced recently to describe this phenomenon.[3] The photosalient effect in the motile crystals represents a direct and visually impressive demonstration of the conversion of light into mechanical motion through a photochemical reaction on a macroscopic scale, which sets the platform for the design of fast biomimetic and technomimetic actuating materials that can mimic animal motions, dynamics of macromolecules, or dynamic technical elements, in the future. In this presentation, we will describe the mechanical response from photosalient single crystals that undergo photoinduced linkage isomerization. To understand the mechanistic details, the mechanism of the process was studied by X-ray photodiffraction, kinematic analysis, IR spectroscopy and mechanical characterization. In contrast to many other solid-state transformations that involve nucleation and propagation of the reaction interface, in this system the reaction proceeds homogeneously whereupon solid solutions form without apparent phase separation.

scholarly journals Reversible Switching of Organic Diradical Character via Iron-Based Spin-crossover

2020 ◽  
Author(s):  
Airi Kawamura ◽  
Jiaze Xie ◽  
Jan-Niklas Boyn ◽  
Kate Jesse ◽  
Andrew McNeece ◽  
...  
Keyword(s):  
Spin Crossover ◽  
Variable Temperature ◽  
Singlet Ground State ◽  
Diverse Range ◽  
Thermally Induced ◽  
Near Ir ◽  
Diradical Character ◽  
Unusual Phenomenon ◽  
Potential Applicability ◽  
External Stimuli

Organic diradicals are uncommon species that have been intensely studied for their unique properties and potential applicability in a diverse range of innovative fields. While there is a growing class of stable and well characterized organic diradicals, there has been recent focus on how diradical character can be controlled or modulated with external stimuli. Here we demonstrate that a diiron complex bridged by the doubly oxidized ligand tetrathiafulvalene-2,3,6,7-tetrathiolate (TTFtt<sup>2−</sup>) undergoes a thermally induced Fe-centered spin-crossover which yields significant diradical character on TTFtt<sup>2−</sup>. UV-vis-Near-IR, Mössbauer, NMR, and EPR spectroscopies with magnetometry, crystallography, and advanced theoretical treatments suggest that this diradical character arises from a shrinking TTFtt<sup>2−</sup> π-manifold from the Fe(II)-centered spin-crossover. The TTFtt<sup>2</sup><sup>− </sup>centered diradical is predicted to have a singlet ground state by theory and variable temperature EPR. This unusual phenomenon demonstrates that inorganic spin transitions can be used to modulate organic diradical character.

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