On August 6, researchers reported in the journal Chem ("Chemistry") under Cell Press that they synthesized a positively charged fluorescent dye into a new type of material called small molecule ion isolation lattice (SMILES). In, the brilliant light of the compound can be seamlessly transformed into a solid crystalline state. This progress overcomes the long-standing obstacles to the development of fluorescent solids and contributes to the development of the brightest materials currently known.

"These materials have potential in any technology that requires bright fluorescence or designed optical properties, including solar energy harvesting, bioimaging, and lasers," said Amar Flood, a chemist at Indiana University. He and Bo Laursen of the University of Copenhagen in Denmark are both senior authors of the paper.

"In addition, there are some interesting applications, including up-conversion of light in solar cells to capture more solar spectrum, light-switching materials for information storage and photochromic glass, and 3D display technology. Circularly polarized fluorescence." Flood said.

Although there are currently more than 100,000 different fluorescent dyes available, almost none of them can be mixed and matched in a predictable manner to make solid optical materials. When dyes enter the solid state, they tend to undergo "quenching" due to their behavior when closely packed, which reduces the fluorescence intensity and produces a softer glow.

"When the dyes stand side by side in a solid, the problem of quenching and coupling between the dyes arises." Flood said, "They can't help'touching' each other. Like a child sitting there listening to a story, they interfere with each other. No longer behave like an individual."

To solve this problem, Flood and his colleagues mixed a colored dye with a colorless solution containing cyanostar. Cyanuric acid is a star-shaped macrocyclic molecule, which can prevent fluorescent molecules from interacting during the solidification of the mixture and maintain its complete optical properties. When the mixture becomes a solid, SMILES is formed, and then the researchers turn it into crystals, precipitate it into a dry powder, and finally make it into a thin film or directly combine with the polymer. Since the large ring of cyanostar has become a building block similar to a checkerboard, the researchers only need to insert a dye into the grid without further adjustments, and the structure will take on its color and appearance.

Although previous research has developed a method of using macrocyclic molecules to separate dyes, it relies on colored macrocyclic rings to complete this work. Flood and his colleagues discovered that the large, colorless ring is the key.

"Some people think that colorless macrocycles are unattractive, but they allow the isolated lattice to fully express the bright fluorescence of the dye and are not hindered by the color of the macrocycle." Flood said.

Next, the researchers plan to explore the properties of the fluorescent material formed using this new technology, in order to realize the full potential of the material in a variety of different applications when working with dye manufacturers in the future.

Flood said: "These materials are brand new, so we don’t know which of their inherent properties can provide better functions. We don’t know the limits of the materials. Therefore, we need to fundamentally understand how it works, Creating new properties provides a robust set of design rules. This is essential for putting these materials in the hands of others-we want to seek crowdsourcing and collaborate with others in this regard."