Nav: Home

Tiny glow sticks

June 08, 2017

Optical data transmission allows information to be transmitted as light by way of optical waveguides in fiber optic networks. Chinese researchers have now developed microscale optical waveguides. As reported in the journal Angewandte Chemie, they have made microrods of lanthanide metal-organic frameworks. Their particular crystal structure ensures low-loss light conduction and the emission of polarized light.

Lanthanides are a group of metals whose special electronic structure makes them attractive for use in optoelectronic applications. Metal-organic frameworks (MOFs) based on lanthanides (Ln-MOFs) offer a wide range of possibilities for targeted variations in structure. MOFs are lattice-like structures made of metallic "nodes" bridged by organic connectors.

Well-defined, microscale Ln-MOFs have remained a rarity, however. Now, things have changed with the new micro-rod Ln-MOFs, which have potential as microscale waveguides. Led by Dongpeng Yan and Yong Shen Zhao at Beijing Normal University and the Chinese Academy of Sciences (Beijing, China), the researchers chose to use benzenetricarboxylic acid (BTC) as their organic building block. This compound strongly absorbs UV light and has electronic energy levels well matched with lanthanides. In a self-organization process under certain synthetic conditions, the BTC molecules and lanthanide ions assemble into crystalline microrods.

Within the crystal, the BTC molecules function as tiny "light antennas": they capture light and very efficiently pass it on to the lanthanide ions in a radiationless energy-transfer process. The lanthanide ions then emit the energy as luminescence whose color varies depending on the lanthanide used. Terbium MOFs emit green light; europium MOFs glow red. Doping terbium MOFs with 5% europium results in orange luminescence.

Viewed under a microscope, rods evenly irradiated with UV light have very bright points at both ends while only weakly glowing otherwise. The spectrum of the emitted light is constant along the length of the rods. The microrods are thus acting as low-loss optical waveguides. It is also interesting that the light emitted at the ends is circularly polarized and evenly distributed over the cross-section of the rods.

This behavior results from the special crystal structure of the microrods, in which the lanthanide ions wind in a helical chain along an axis of the crystal. The chains are bound together by phenyl groups of the BTC, which form impenetrable walls for the light. The overall result is a three-dimensional lattice penetrated by square channels.

With their low light loss and high photoluminescence quantum yield, these novel one-dimensional microstructures could serve as an effective platform for the development of new systems of color tunable optical waveguides with polarized emissions.

(2926 characters)

About the Author

Dr. Dongpeng Yan is a full professor in the College of Chemistry, Beijing Normal University (PR China). His research interests are inorganic-organic hybrids, molecular co-crystals, and host-guest chemistry. In particular, he has been working in the field of photofunctional materials for over 10 years, and has published more than 100 research papers.

mailto:yandp@bnu.edu.cn
-end-


Wiley

Related Lanthanides Articles:

Radiation damage spreads among close neighbors
A single x-ray can unravel an enormous molecule, physicists report in the March 17 issue of Physical Review Letters.
New technology for pathogen detection driven by lasers
Purdue innovators have developed a lanthanide-based assay coupled with a laser that can be used to detect toxins and pathogenic E. coli in food samples, water and a variety of industrial materials.
Science snapshots
This edition of Science Snapshots highlights an investigational cancer drug that targets tumors caused by mutations in the KRAS gene, a new library of artificial proteins that could accelerate the design of new materials, and the natural toughening mechanism behind adult tooth enamel.
Six degrees of nuclear separation
For the first time, Argonne scientists have printed 3D parts that pave the way to recycling up to 97 percent of the waste produced by nuclear reactors.
New sensor detects rare metals used in smartphones
A more efficient and cost-effective way to detect lanthanides, the rare earth metals used in smartphones and other technologies, could be possible with a new protein-based sensor that changes its fluorescence when it binds to these metals.
Bacterial protein could help find materials for your next smartphone
A newly discovered protein could help detect, target, and collect lanthanides, rare-earth metals used in smartphones, from the environment.
A versatile method for the protection of carbonyl compounds by camphorsulfonic acid
In this paper, camphor sulfonic acid-catalysed protection of various carbonyl compounds is developed.
Light-emitting nanoparticles could provide a safer way to image living cells
A research team has demonstrated how light-emitting nanoparticles, developed at Berkeley Lab, can be used to see deep in living tissue.
Research finds new molecular structures in boron-based nanoclusters
Researchers have shown that clusters of boron and lanthanide atoms form interesting 'inverse sandwich' structures that could be useful as molecular magnets.
Scientists create continuously emitting microlasers with nanoparticle-coated beads
Researchers have found a way to convert nanoparticle-coated microscopic beads into lasers smaller than red blood cells.
More Lanthanides News and Lanthanides Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at Radiolab.org/donate.