How large is the effect of impurities in commercial pyrene on the fluorescence? I am to recrystallize Pyrene, in small scale, to be used as extrinsic fluorescence probe.
I'd appreciate some practical tips on ratios to use, temperature and N2(g) flow for evaporation and if there is a preference for either acetone or ethanol.
Dear Andreas Martin Hugerth ,
These publications might good methods of recrystallization:
Article Effect of cationic surfactants on the conformation transitio...
Article Determination of Electrochemical Heterogeneous Electron Tran...
I know that sublimation could be an excellent method for obtaining ultrapure pyrene.
I suggest you to have a look on the book: "Purification of Laboratory Chemicals" by Perrin which might be not so difficult to find online.
Hope this could help you !
You will need to first wash the commercial product to remove any comparatively polar material in a sequence of (high to) decreasing polarity and in the non-dissolving solvent, or partitional washing between polar and non-polar, non-miscible solvents. Once you reach the maximum purification in the process (2-3 sets), the pyrene which is pale yellow in color can be crystallized with a non-polar solvent. If appropriate solvents for the purpose can be generated by mixing a small to bigger ratio among the two (binary system) or many solvents. The impurities are also graphene, GO, PEt, etc. and each step of purification needs to be carefully taken up. For high bulk use dissolution warming (enough heat to dissolve) and cooling, seeding method. Probably you need a small amount of pure material. Hope that works!
Dear Andreas Martin Hugerth many thanks for asking this very interesting technical question. Pure pyrene should be colorless. For some basic informations about the physical and chemical properties of pyrene please have a look at the following useful link:
https://pubchem.ncbi.nlm.nih.gov/compound/Pyrene
In the following article it is mentioned that pure pyrene was obtained by repeated (three times) recrystallization from methanol:
Solubility in Binary Solvent Mixtures: Pyrene Dissolved in Alcohol
+ Acetonitrile Mixtures at 299.2 K
(see attached pdf file)
Occasionally, pyrene samples are slightly yellow. This is due to contamination with small amounts of tetracene. According to the article "Hydrocarbons" (see page 179 in the attached pdf) this impurity can be removed by addition of some maleic anhydride.
I hope this helps. Good luck with your work and best wishes, Frank Edelmann
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