As mentioned, 2-methyltetrahydrofuran is quite good at forming glasses, I use it quite often for MCD (which is very sensitive to glass quality). The only problem that I've found is that solid 2-MeTHF has an annoying tendency of cracking quite spectacularly if not cooled slowly down to sub-LN2 temperatures (e.g. LHe).  For more polar compounds, nitriles have worked well for me (e.g. butyronitrile, propionitrile). Finally, for those compounds which are soluble in them, n-alkanes make absolutely fantastic glasses, esp. if you use an alkane of approx. the same size as your compound.

Here is a paper which has a nice discussion of useful solvents and solvent mixtures: http://dx.doi.org/10.1021/j100809a510

Edit: forgot to mention, 2-MeTHF can be cleaned up nicely by passage down a basic alumina column...but don't keep it too long!

Thanks a million, Peter. It does help a lot! My not considering the alcoholes is dictated by the presence of carboxylic groups that would form hydrogen bonds with the hydroxyl groups of the alcohol, which would affect the spectra. But I will try the alcohol mixture anyway now.

But you suggested 2-methyl-THF. And what about THF or dioxan - they are not so much different - does the methyl group really make such a difference?

My very best regards! Marcin

Thank you again for detailed explanation. I will keep experimenting (being a theoretician I find it quite refreshing ;) and will let you know what I have found.

Marcin

A mixture of Ethanol-Methanol( 4:1) or Ethanol- glycerol mixtures forms transparent glass at 77K for  absorbance and fluorescence measurements. Ofcourse there are many mixtures of solvents that can be used based on the nature of the sample and solubility.

Thanks, Narayanan! Would you have any suggestion off hand that would not contain protic solvent (no alcoholes in particular). The imid groups may behave in many different ways in the presence of alcoholes... 

Marcin

As mentioned, 2-methyltetrahydrofuran is quite good at forming glasses, I use it quite often for MCD (which is very sensitive to glass quality). The only problem that I've found is that solid 2-MeTHF has an annoying tendency of cracking quite spectacularly if not cooled slowly down to sub-LN2 temperatures (e.g. LHe).  For more polar compounds, nitriles have worked well for me (e.g. butyronitrile, propionitrile). Finally, for those compounds which are soluble in them, n-alkanes make absolutely fantastic glasses, esp. if you use an alkane of approx. the same size as your compound.

Here is a paper which has a nice discussion of useful solvents and solvent mixtures: http://dx.doi.org/10.1021/j100809a510

Edit: forgot to mention, 2-MeTHF can be cleaned up nicely by passage down a basic alumina column...but don't keep it too long!

Thank you, Benjamin for sharing your experience!I will definitely have a wide area for experimenting... For a theoretician like myself it is the whole new world ;)

Have you tried methy cyclo hexane and methyl cyclo pentane 1: 1 mixture. I am not sure how polarity gonna work here but they are good solvents for Low temp Absorbance measurements.  If not yeah 10 % meoh in Ethanol might work too.....Good luck