Yes you can use cinnamon. I use it, but it's imperative that stray cinnamon doesn't fall on the roots as it can be extremely desiccating. When applying cinnamon or doing any treatment on the leaves, I like to water the plants first so the roots are saturated, I then place a little paper towel at the base of the plant to cover around the roots.
You can also try making your own alcohol/cinnamon concentrate, I keep it in a spray bottle with a few cinnamon sticks in it. I follow the recipe on Ray's website:
Home Remedies