Fluorescent materials are very popular in props for parties and celebrations, but they also used more discreetly in various applications, from glasses and windows that change their transparency in the light of variations in light to data storage systems.
And these applications can now be greatly expanded, thanks to the work of Christopher Benson and colleagues from the universities of Indiana, USA, and Copenhagen, Denmark.
Not only did Benson create the world’s brightest fluorescent material, but he first found a way to make solid materials fluorescent, a goal long pursued by chemists around the world.
Although there are currently more than 100,000 different fluorescent dyes available, almost none of them can be mixed and combined in predictable ways to create solid optical materials. Dyes tend to suffer “suppression” of the fluorescence phenomenon when they enter a solid state due to the way they behave when they come together, decreasing the fluorescence intensity and presenting a very smooth shine.
Ionic insulation networks
To overcome this problem, Benson mixed a colored dye with a colorless solution of cyanostar, a star-shaped macrocycle molecule that prevents fluorescent molecules from interacting while the mixture solidifies, which allowed it to keep its optical properties intact.
Fluorescence can vary by color or the color of the light with which the material is energized.
[Image: Amar Flood Lab / Indiana]
As the mixture becomes solid, structures are formed that the researchers called “small molecule ionic isolation networks”. These networks are then transformed into crystals, precipitated in dry powders and, finally, dispersed in a thin film or incorporated directly into polymers.
As cyanostar macrocycles form networks that resemble a chessboard, it becomes possible to simply insert a dye into the network – without any additional adjustments, the structure readily assumes its color, shining with strong intensity.
Fluorescence for all uses
“These materials have potential applications in any technology that requires bright fluorescence or requires optical design properties, including solar energy collection, bioimaging and lasers.
“In addition, there are interesting applications, which include the upward conversion of light to capture a larger part of the solar spectrum in solar cells, switchable light materials used for storing information and photochromic glasses, and circularly polarized luminescence, which can be used in 3D display technology, “predicts Professor Amar Flood, one of the team’s coordinators.
Plug-and-Play Optical Materials from Fluorescent Dyes and Macrocycle