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Specialty Chemistry Forums => Materials and Nanochemistry forum => Topic started by: Bublik on September 07, 2016, 10:15:12 AM

Title: Stubborn citrate-capped nanoparticles don't want to change phases
Post by: Bublik on September 07, 2016, 10:15:12 AM

Hey guys,

I'm trying to switch the caps of my gold nanoparticles to from an aqueous citrate-capped solution to an organic thiol-capped solution. I've tried various ways to do this, all of which being variations of mixing the Ct-capped nanoparticles with the desired thiol in an organic solvent, with the idea that the thiol has a higher affinity for the gold and will displace the citrate, resulting in the desired thiol-capped hydrophobic nanoparticles in the organic layer. The Ct-capped nanoparticles range in diameters from ~6 to 24nm.

This procedure is described in countless papers and it just doesn't work that easily. Does anybody have any experience/advice/suggestions for this? I've tried using some phase transfer catalysts, different variations of equivalencies and solvents, and still to no avail.

Title: Re: Stubborn citrate-capped nanoparticles don't want to change phases
Post by: ididnotgettheidiwant on March 06, 2018, 10:57:42 AM

Hi,

Did you solve this problem? I'm having a similar issue and would love to hear how you solved it.

Thanks!

Title: Re: Stubborn citrate-capped nanoparticles don't want to change phases
Post by: wildfyr on March 06, 2018, 12:49:40 PM

Try heating it up a bit or adding a little weak base.

Title: Re: Stubborn citrate-capped nanoparticles don't want to change phases
Post by: wildfyr on March 06, 2018, 01:49:27 PM

Ididnot, would you care to share the identity of the thiol?

Title: Re: Stubborn citrate-capped nanoparticles don't want to change phases
Post by: ididnotgettheidiwant on March 06, 2018, 03:29:50 PM

Mercaptoacetic acid. Thanks for your suggestions!

Title: Re: Stubborn citrate-capped nanoparticles don't want to change phases
Post by: wildfyr on March 06, 2018, 04:57:28 PM

This paper seems highly relevant https://pubs.acs.org/doi/pdf/10.1021/la504000v. It doesn't just stir in mercaptoacetic acid to the citrate capped NPs.