I have reduced the HAuCl4 solution in ethanol and found green solution using a reducing agent, it exhibits two SPR bands one at 456nm and other at 628nm. but according to literature gold nanomaterials posses SPR band at 500nm or beyond it. Is this any complexation taking place or there is formation of a nano sized gold? plz help. I have not characterized the samples through imaging techniques.
thanks a lot but can you suggest what type of reaction is there , is there any kind of nano sized gold or is it a complexation reaction?
What kind of reducing reagent did you use? Could be the absorption band place at 456 nm due to the excess of this reagent or by-products of the reaction?, I agree with Khosro Zangeneh that this band is not probably due to Au nanoparticles/nanorods/nanowires.
Cheers,
I used a drug as reducing agent that contains S atom and N in a six membered ring, when I record UV-Vis spectra of the drug only then the absorption band was at 250. the color of the green colored solution turned to dark pink after 24 hrs and only one absorption band is found after 24 hrs which lies at 520nm.
Maybe, you are forming a coloured intermediate of Au+ with your drug which is further reduced to AuNPs. In this case in a first stage of seeding, some anisotropic particles (green colour), how hnows, are forming which slowly evolves to isotropic ones (semispherical, regular decahedra, octaedra, etc with red/pink colour) by an etching process (maybe favored by the pH).
It would be interesting to know what's happening at different reaction times by TEM to depicts a possible scheme.
Cheers
The peak around 456 nm not due to SPR of Gold nano particles. When using weak reducing agent like ascorbic acid, it reduces Au3+ to Au1+.For nanopartcile formation
Au 3+ must be reduced to Au(0). The green colour may be due incomplete reduction
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