Gifu University in Japan announced on August 3, 2016 that it had developed a fluorescent substance. Although it is a single fluorescent molecule, the fluorescent color can be changed by adding acid. By adjusting the specific acid mixing ratio, white fluorescence can also be achieved. In the future, it is expected to be used in organic EL lighting, organic EL displays, chemical sensor chips for detecting heavy metals, etc.
The change after adding acid to the fluorescent luminescent compound, the blue gradually becomes lighter, turning into white and orange.
The chromaticity coordinates of color change. After adding acid, the color changes linearly.
The research team had previously developed a new fluorescent compound with nitrogen atoms introduced at specific positions of a five-membered ring during the study of a group of low-molecular organic compounds (Aminothiazole) containing sulfur atoms and multiple nitrogen atoms. The research team found that this compound has a very characteristic molecular structure. The five-membered ring part and the part where nitrogen atoms are introduced are greatly distorted. By introducing different substituents or elements at this position, the fluorescent color can be controlled, from blue to red.
This time, by introducing a basic functional group into a specific part of this new fluorescent compound, a substance that can fine-tune the luminous color by adding acid has been realized. Specifically, after adding hydrochloric acid to a blue fluorescent compound, the blue fluorescence gradually disappears and yellow fluorescence is displayed. Moreover, depending on the acid selected, the fluorescent color will be different.
Model of fluorescent luminescent compounds
Molecular structure model of fluorescent luminescent compounds
In addition, by fine-tuning the mixing ratio with specific acids, some blue luminescent compounds can be turned into orange luminescent compounds, thereby achieving white luminescence. The fluorescence of this compound is generated by the neutralization reaction between acid and base. Therefore, after adding acid to form a luminescent color, if a base is added again, the original blue luminescence color can be reproduced.
This compound can emit multiple colors of light through a single molecule, thus helping to simplify the production process of applied products and is expected to be popularized at a lower cost. If it can be successfully dissolved in water or fixed into an organic film in the future, it will be expected to be used in a very wide range of applications.
This research was jointly implemented by Gifu University and Kyoto University as part of the Advanced Matter Conversion Field (ACT-C) strategic creative research promotion business of the Japan Science and Technology Agency (JST) and the "New Academic Field Research" research funding business of the Japan Society for the Promotion of Science (JSPS). The research results were published in the online version of the thesis journal "ChemistryOpen" on August 2, 2016.
ANNA