Researchers from the University of North Carolina at Charlotte recently discovered a new class of molecules with exceptional fluorescent properties. Applications for the new compounds, called thiazolothiazole (TTz) viologens, are infinitely adaptable, including properties that make them potentially useful in OLED televisions and as biomolecular sensors for human cells.
The new study is published in the May edition of the Journal of the American Chemical Society by Alexis N. Woodward, Justin M. Kolesar, Sara R. Hall, Nemah-Allah Saleh, Daniel S. Jones, and Michael G. Walter.
The discovery of the new compounds was an outgrowth of previous work by Walter in photochemistry for solar energy applications. He saw fluorescent and electrochromic properties of compounds that appeared to be eerily similar to methyl viologens, electrochemical compounds with a history of use as herbicides. The TTz molecules are highly fluorescent, and electrochromism allows them to reversibly change color.
“We wanted to try and use these compounds for solar energy conversion applications. We had no idea we would ultimately discover this great fluorescent molecule,” Walter explained. Walter and his team quickly realized that the compounds they were working with were significantly different from methyl viologens, which have electrochromic activity but do not fluoresce. The new compounds could do both.
The new TTz fluorophores are extraordinary for many reasons. First, they have a high quantum yield, a measurement of how efficiently a substance fluoresces. “Their quantum yield is as close to 100 percent as you can get,” Walter said.
The compounds also have stable electrochromic qualities. This means that the fluorescing compounds can be reversibly turned “on” and “off” like a light switch, a remarkable quality that makes TTz fluorophores optimal for applications such as self-tinting windows in cars, buildings, and even airplanes.
Because these stable compounds use little energy, can be used in flexible devices, and fluoresce brightly, there is also a huge potential for their use as organic light-emitting diodes (OLED), which are now being used as a display technology for televisions, phones, laptops, and more. “The applications are certainly far-reaching,” Walter said.
And the potential technology applications don’t end here. Walter’s TTz fluorophore discovery could also serve as a way to create unique new sensors for measuring cellular changes in response to an external stimulus, like a pharmaceutical drug.
“If applied as a molecular sensor, TTz fluorophores could help aid researchers in targeting new drugs,” Walter explained. “We think this fluorescent dye can be a guide, a helper molecule for molecular biologists to help understand more about cell physiology, and how cells interact with each other.”
For now, Walter and his team of researchers are zeroing in on five derivatives of the TTz fluorophores, but there are hundreds more to make from the same starting point – thiazolothiazole – all with unique fluorescent and electrochromic properties. Walter notes that it took a long time to get the conditions just right, and each derivative was a result of starting from scratch, using individual molecular pieces that the researchers had “knit” together. But now, Walter sees himself and his team at the “tip of the iceberg,” where the possibilities of different TTZ fluorophore derivatives are endless.
“What color do you want? We can dial it in,” Walter said. “The possibilities for applying our TTz fluorophores are virtually endless.” Whether creating vibrant color for OLED televisions, visualizing cell activity in response to external stimuli, or tinting plane windows at the push of a button, the newly discovered TTz fluorophores still have stories left to tell.
Source: Michael Walter, Michael.Walter@uncc.edu. Media contact: Jim Hathaway, 704-687-5743, Jbhathaw@uncc.edu.