Dataset Information

High-Power Actuation from Molecular Photoswitches in Enantiomerically Paired Soft Springs.

ABSTRACT: Motion in plants often relies on dynamic helical systems as seen in coiling tendrils, spasmoneme springs, and the opening of chiral seedpods. Developing nanotechnology that would allow molecular-level phenomena to drive such movements in artificial systems remains a scientific challenge. Herein, we describe a soft device that uses nanoscale information to mimic seedpod opening. The system exploits a fundamental mechanism of stimuli-responsive deformation in plants, namely that inflexible elements with specific orientations are integrated into a stimuli-responsive matrix. The device is operated by isomerization of a light-responsive molecular switch that drives the twisting of strips of liquid-crystal elastomers. The strips twist in opposite directions and work against each other until the pod pops open from stress. This mechanism allows the photoisomerization of molecular switches to stimulate rapid shape changes at the macroscale and thus to maximize actuation power.

SUBMITTER: Aßhoff SJ

PROVIDER: S-EPMC5363340 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature

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High-Power Actuation from Molecular Photoswitches in Enantiomerically Paired Soft Springs.

Aßhoff Sarah J SJ Lancia Federico F Iamsaard Supitchaya S Matt Benjamin B Kudernac Tibor T Fletcher Stephen P SP Katsonis Nathalie N

Angewandte Chemie (International ed. in English) 20170209 12

Motion in plants often relies on dynamic helical systems as seen in coiling tendrils, spasmoneme springs, and the opening of chiral seedpods. Developing nanotechnology that would allow molecular-level phenomena to drive such movements in artificial systems remains a scientific challenge. Herein, we describe a soft device that uses nanoscale information to mimic seedpod opening. The system exploits a fundamental mechanism of stimuli-responsive deformation in plants, namely that inflexible element ...[more]

PMID: 28181400

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Project description:Structurally engineered molecules which can behave as stimuli-controlled mechanical nanomachines such as molecular shuttles, rotors, ratchets, and springs are important in several research areas, including molecular robotics, actuation, sensing, cargo transportation, etc. Helicenes, by virtue of their unique screw-type structures, were proposed as functional models for molecular springs; however, experimental realization has remained an elusive and unmet task until now, because of the lack of appropriate helicene molecules consisting of backbone-decorated dynamic architectures. Aiming to explore this unearthed direction, we present herein a novel class of modular flexible heterohelicenes with a stimuli (acid/base and light)-responsive core and peripheral modules. By applying pH (at core-embedded free imidazole sites) and light (at backbone-tethered dithienylethene units) stimuli, we demonstrate that these flexible heterohelicenes exhibit spring-like movement, with the reversible contraction/extension of the helical pitch. The uniquely functionalized structure of these molecules played a critical role in bestowing such capability, as revealed by crystallographic, spectroscopic and computational data. Careful assessment disclosed that the protonation/deprotonation-induced reversible generation and delocalization of positive charge throughout the π-conjugated helical rim switch the operative interactions between the π clouds of the terminal overlapping arene rings of the helicenes between repulsive and attractive, leading to extension/contraction of the helical pitch. On the other hand, in the case of the light stimulus, it was analyzed that the light-induced ring-closure of the photoactive dithienylethene units created a geometric distortion causing the helicenic wings to bend outward from the helicene rim, which resulted in extension of the helical pitch. The photo-assisted (or thermal) reverse ring-opening reaction converted the system to its original conformation, thus enabling the helicene molecule to display spring-like reversible extension/contraction motion. The new insights on the reversible dynamic features of this class of heterohelicenes under the influence of external stress would guide crucial design principles of helicene-based molecular springs for potential applications.

Dataset Information

High-Power Actuation from Molecular Photoswitches in Enantiomerically Paired Soft Springs.

Publications

High-Power Actuation from Molecular Photoswitches in Enantiomerically Paired Soft Springs.

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