I have a fused tetracyclic molecule having multiple hydroxyl groups at the peripheri. Can it form the micelle in the solution?
Dear Nadim,
For a molecule to be surface active it should have clearly spacially separated hydrophilic and hydrophobic domains. It sounds like your molecule has its hydroxyls spread over the tetracyclic structure so in that case the hydrophilic part is smeared out over the molecule, so something like C-C-C-C-C-C-X2 may be surface active whereas X-C-C-C-C-C-C-X probably is not.
Next, it depends which solvent you are using. In water micellization is pretty common, but the same molecule would not form micelles in for instance methanol. If you work with water as a solvent the easiest way to check either surface tension or conductance (if your molecule forms ions) as a function of concentration; a distinct change in properties would indicate micellization.
There are many methods to demonstrate micelles and determine critical micelle concentration (the lowest concentration at which micelles are formed), so you can probably find one that is suitable for your specific substance.
Kind regards, Leo
Dear Nadim,
Of course, only diphilic, as a rule, long-chain molecules with a long hydrocarbon radical and a hydrophilic group (like SO3- or N(CH3)3+, or (C2H4O)n at its end can form classical colloidal micelles. This is not your case. But if your tetracyclic molecules have aromatic cycles (like polycyclic aromatic hydrocarbons), they can form so-called staсking aggregates when one molecule is above the other forming a stack of many molecules. Example are bile acids that form micelle-like structures. Such aggregates are thermodynamically unstable, unlike classical micelles.
Dear Sergei. Thanks for your valuable comments. My tetracyclic fused molecule has both aromatic rings at the preipheri and both internal rings are non aromatic.
If your solutions have surface activity, then with the appearance
of their aqueous solutions, at least a small foam should appear.
Then it is possible that small aggregates can form in the
solution.
Dear Nadim,
I guess conductivity is the easiest method to determine whether your compound will form micelles or not.
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