I did the synthesis of SPION by the following method:
Briefly, 0.71 g of iron acetylacetonate was mixed with 20 mL of phenyl ether,
2 mL of oleic acid, and 2 mL of oleylamine under inert atmosphere with vigorous stirring. To this solution 2.58 g of 1,2-hexadecanediol was added. The reaction mixture was heated to around 210 °C with reflux for 2 h, maintaining oxygen-free conditions. The reaction mixture was cooled to room temper-ature, and then, ethanol (degassed) was added to precipitate the black-colored product. The precipitate was separated out by centrifugation. The precipitated product was then washed with a series of solvents starting with hexane, followed by a mixture of hexane and ethanol, and then finally with ethanol. The product was dispersed in ethanol and separated magnetically and dried to obtain a black-colored powder, which could be well-dispersed in toluene.
The problem is during purification when I added hexane to black ppt it converts in to black colored liquid which have no ppt at all.
I am really confused as to what to do? Where are my SPIONs?
if they are SPIONs , by any which way they should be separated by any type of external magnet . Try keeping the solution for a longer time on the magnet, it will help you out.
It will not separate if your washing solvent contains hexane or chloroform. For that matter even THF. Basically toluene, THF, hexane and chloroform are the four solvents in which it disperses completely to form colloidal solutions. If this happens even the reguler NdFeB magnets will not separate it from the sparkling brown/black colloidal dispersion.
When i do oleic acid based synthesis, I wash it repeatedly with ethanol ONLY. During the last washing i place it in bath sonicator for 5 minutes. It works fine for me.
Sachin, it will be useful if you include the reference. I guess you are following a very good paper from Shouheng Sun's group. Precipitating NPs require a very little amount of good solvent. If you added too much hexane, it will be hard to precipitate them in ethanol. You have to add only a little bit of hexane (this depends on the scale, but it can be less than 0.5 mL). If you don't do this and just add ethanol, you will never get rid of excess ligands properly. Putting NPs in sonicator will detach ligands from the surface (consider mass equilibrium as you get rid more and more of the excess ligands) and worsen your NP's dispersity.
Friends,
When I am doing the contrifugation of black ppt this, it get stuck to the wall of test tube.
I dont know whats going wrong. please help.
I am also working on the synthesis of Iron Oxide nanorods, and I stored my nanorods in HEXANE, but I found the nanorods settles down , is it normal ? OR my nanorods are not synthesized correctly as they are not able to disperse completely in Hexane. Please tell me reasons for it.
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