Scientists from United Arab Emirates and Russia have now systematically examined crystals that move when irradiated by light. In the journal Angewandte Chemie they present the first quantitative kinematic analysis of this phenomenon, which they have termed the photosalient effect.
When irradiated with UV light, micrometer- to millimeter-sized crystals of the cobalt coordination complex [Co(NH3)5(NO2)]Cl(NO3) cover distances over thousands of times larger than themselves. Why do they do this?The nitrite ligand (NO2) is normally bound to the central cobalt ion through its nitrogen atom. This bond is broken by the irradiation and the ligand rotates a little to use one of its oxygen atoms to bind to the cobalt instead. This isomerization produces strain in the crystal. The strain is dissipated through movement and fracturing. The crystals jump and may even explode.
The distance covered depends on the duration and intensity of the irradiation. The crystals only jump after a certain period of latency during which stress builds up. When it reaches a threshold, the stress is released all at once. Smaller crystals start flipping sooner than larger ones. Interestingly, the intensity of the irradiation also determines the type of effect. Intermediate intensities primarily cause rolling and jumping, higher intensities cause more splitting off of debris. The highest intensities primarily cause the crystals to split into two equal pieces.
The scientists are convinced that the effects result from a cooperative mechanism. The rotation of individual ligands causes small intramolecular perturbations that are spread and amplified over the network of hydrogen bonds connecting the ions within the crystal lattice. This network acts like a spring that is wound by the irradiation and relaxes through the movement or splitting of the crystal.The rigidity of the springs was confirmed in precise single-crystal diffraction experiments where the sample was exposed to high pressure.
The conversion of light energy to mechanical movement could be useful for the design of materials that imitate the movement of animals, or dynamic technical components in devices like nanomachines.About the Author
Author: Panèe Naumov, New York University Abu Dhabi (United Arab Emirates), https://nyuad.nyu.edu/research/centers-institutes/naumov-group.htmlTitle: Dynamic Single Crystals: Kinematic Analysis of Photoinduced Crystal Jumping
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201303757The original article is available from our online pressroom at http://pressroom.angewandte.org.
Contact: Editorial office: email@example.com
Panèe Naumov | Angewandte Chemie
The birth of a new protein
20.10.2017 | University of Arizona
Building New Moss Factories
20.10.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
20.10.2017 | Information Technology
20.10.2017 | Materials Sciences
20.10.2017 | Interdisciplinary Research