Hi Charles,

After checking in Reaxys I found a few publications that report extinction coefficients for Nile red in CHCl3:

Photochem. Photobiol. Sci., 2020,19, 1382-1391 (Table A1 in ESI)

Tetrahedron Letters, 2009, 50, 1131–1135 (Table 1)

J. Am. Chem. Soc. 2010, 132, 32, 11119–11124 (Figure SI 5 in ESI) (note that here extinction coefficient in M-1 cm-1 will be obtained by multiplying the presented value by molar mass of the dye)

Though, I noticed that the values are different in these sources, in the range 32600 - 61000, so almost two-fold. :O Probably would be best to do own measurement and see how it compares to those sources.

For curcumin I found only one reference:

Chem. Eur. J. 2016, 22, 5219, (Table S2 in ESI, compound 8-H)

I hope this helps, though like I mentioned it may be a good idea to get your own measurement and rely on that.

Best regards,

Evgeny

Hi Charles Garzon , I can tell you a different way If you would like to approach to calculate the molar absorption coefficient. Simply you can prepare a known concentration standard solution of those dyes you want to calculate (i.e., 10 uM). Now using a UV visible spectrometer you can record the absorption spectra in the desired solvent (I would recommend you to keep your absorbance readings in the 0.1 to 0.8 range approximately). Once you obtain the absorbance readings and desired absorption maxima, you can simply use Beer-Lambert law.

A = eCl

Where A is you r absorbance of the sample, C is the concentration of the sample and l is your path length (usually it is 1 cm for the standard corvette)

e is your molar absorption coefficient can be calculated from this equation.

Hope this help.