fluorescence

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Separation of a highly fluorescent anthranilic acid derivative from the reaction mixture.

The upper organic layer dissolved almost completely my compound from the reaction mixture and could be separated in one step. A good point was that the compound had a really strong fluorescence and if I placed an UV lamp next to the separation funnel it was easily observed that the water phase contained almost none of the title compound. 

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Here’s some fun kitchen chemistry you can try out yourself – fluorescent turmeric!

Finally got the pure Nile Red in solution, just need to evaporate to get the pure dye.

Interesting fact: Nile Red is a solvatochromic dye. What does this mean? Solvatochromism is the ability of a chemical substance to change color due to a change in solvent polarity, so it has different color in different solvents. Also its emission and excitation wavelength both shift depending on solvent polarity, so it fluoresces with with different color depending on the solvent what it’s dissolved in. 

In this case it was dissolved in dichloromethane.

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Scheelite from Xuebaoding Mountain, Pingwu County, Sichuan Province, China, shown under white light, short wave ultraviolet and mid-wave ultraviolet light.  The red fluorescence under mid-wave UV is due to the presence of the rare earth element samarium.  Scheelite is the main ore of tungsten, a strategic metal used in steel manufacturing.  Prospecting is done at night with short wave ultraviolet light due to its intensely bright fluorescence.  

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There are several compounds, that has a near no emission under UV light at room temperature, but when it’s cooled down with liquid nitrogen, the emission increases a lot. This phenomena is called low temperature fluorescence thermochromism.

In this case I prepared an organic compound what is a white crystalline solid at room temperature, but when it is cooled below -100 °C it emits a bright blue light when exposed to UV light.

While being irradiated with UV light, as temperature drops in the flask and the crystals reach a specific temperature, they start to emit light. It’s a quite adorable thing, since you can actually see the temperature.

How does it work? Depending on the temperature the bonds in these molecules change a lot what means they can absorb and emit different wavelength. When irradiated with UV light at room temperature, the compound emits some visible light, but when it is  cooled down with liquid nitrogen the compound emits a different wavelength light with a different intensity.