Smearing usually happens due to ionic interactions as opposed to just hydrophobic interactions.

If you add acid to your mobile phase (1% TFA) this could solve the smearing issue. Another thing to try would be to add base (1% NEt3) to your mobile phase.

these tricks work when you are purifying amine compounds that smear but I think they will work when you have amino silica stationary phase as well.

yeah i tried adding a few drops of acetic acid that did not work however. Maybe a base will work but I will have to see if we have a good base for that on the lab. if there are any more suggestions I would love to hear them!

Are you purifying the compound depicted in this link?

https://pubchem.ncbi.nlm.nih.gov/compound/Fluorescein-diacetate#section=2D-Structure

If so, I don't see any ionizable groups on that molecule that would be affected by adding a solvent modifier. As I read that the TLC plate is an amine bonded to silica, it is already basic, so triethylamine won't help much. Adding acetic acid won't help as the amine bonded phase gets converted to a weak ion exchange plate, with an acetate counter-ion.

Another cause for TLC plate streaking is decomposition of the compound running on the plate. Please consider base-catalyzed ester hydrolysis, where the products are more polar phenols and alcohols which move more slowly on the plate. The amine (basic) bonded phase may be contributing to decomposition.

Try a cyano or diol bonded phase for normal phase TLC, or a reverse phase TLC plate.

To stop tailing in HPTLC, the selection of proper solvent system is essential.

Oh! also maybe the plate is overloaded? Maybe thats why there is tailing as well

Hello, you may try to dilute the product concentration or change the mobile phase or add acid or alkali.

Also sometimes when compounds react on the plate they smear. in the case you would have to change the plate chemistry (i.e. reverse phase instead of normal phase silica)