I read an article in a science newsletter about making colloidal gold with cinnamon as a green alternative to using dangerous chemicals. Well, the people on this forum already know how to make colloidal gold without dangerous chemicals, but I thought I would try it out.
The article said that the phytochemicals would bond with the gold nanoparticles and had anti-cancer properties.
I took about 1/4 teaspoon of real cinnamon (not the kind in the grocery store) and boiled it in 60ml of water for 10 minutes to extract whatever agents were in it. I filtered it to take out the insoluble part.
Next, I mixed 1.25ml gold chloride in 250ml of water and heated it to boiling.
Then I added the cinnamon juice drop by drop to the gold chloride solution. It soon started to turn pinkish. After it started to turn color, I just reheated it and left it set until cool.
The resultant was indeed nano gold particles, but instead of ruby red, the color was purple.
The article talked about cinnamon, but the product sold in the US as cinnamon is actually cassia. Real cinnamon comes from Sri Lanka, and has a different flavor than the grocery store cinnamon. Anyway, when someone says cinnamon in the context of chemistry, we don't know which they used.