There are some chemical compounds that can glow in the dark. This kind of compound could be easily seen in children toys, sometimes scientists use these compounds for their research. As the demand of these compound growing day by day, scientists found an another process for producing photoluminescent (PL) compounds.
A group of scientists named, the Coordination Chemistry and Catalysis Unit from the Okinawa Institute of Science and Technology Graduate University (OIST) started working on the new of producing PL. Basically, there are two methods: the conventional metal-ligand system, and aggregation based system. The first method is quite rigid and it is impossible to modify. It requires a complex ligand that strongly binds to a metal ion which allows them to emit light. But, the second is driven by weak interactions between different molecules or their parts and it is typically difficult to control.
Researchers of OIST combined the best parts of both methods to produce PL molecules. Their findings were first published in the Journal of Materials Chemistry C. Postdoctoral researcher Dr. Georgy Filonenko from the Coordination Chemistry and Catalysis Unit at OIST explained,“We wanted to create better photoluminescent compounds by combining the two previous concepts. The flexibility of the weak aggregation driven complexes and the controllability of the conventional metal-ligand system”.
According to Science Daily, Prof. Julia Khusnutdinova who was the lead researcher of the experiment designed compounds whose intermolecular interactions are responsible for photoluminescence. Without intermolecular aggregation, they have found the tunability of the aggregation-based system confined to a single molecule as a result.
Those molecules which Dr. Filonenko synthesized, consisting a ligand and a copper ion whose interactions produce photoluminescence. This is quite similar to the conventional metal-ligand system but, the OIST-synthesized ligand is not rigid and it has two cyclic-bonded atom structure. Those cyclic-bonded atomic structures are referred as rings and surprisingly, by changing the distance between those rings researchers were able to change the color emission from those molecules.
When those rings come closer then those molecules emit yellow or orange colors but, while those rings move apart then the emission turns red. Dr. Filonenko explained that those compounds could be used as sensors due to their very high sensitivity to the surrounding environment.