Potassium Permanganate (Purple...burning purple)

Potassium permanganate, or KMnO4, is one of the most well-known oxidizing agents in chemistry. Unfortunately, it's a bit like taking a gun to a knife fight...

One of the big downsides of permanganate is the fact that it's a very polar ion. Crown ethers to the rescue.

Permanganate is a beautiful purple color in solution (almost black as the solid, partly because it's such a rich purple, partly because of MnO2 contamination), which I maintain is responsible for at least part of its popularity. It is a beast, as I alluded to earlier - it will take toluene down to benzoic acid (or even generic alkylbenzenes). It has some milder oxidations - for instance, if you use it on an olefin on ice, it will supposedly give you the cis-vic-diol. Everybody just uses OsO4 for this if they're sane, as far as I know.

Permanganate will do one lively reaction that young children, sadly, aren't able to see anymore. If you build a wee pile of permanganate and dribble some glycerine in the center, you'll be rewarded with a beautiful purple flame. See here for one of the animations that "Chemistry Comes Alive!" hasn't snatched from the public web.

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Crown ethers are an unusual series of molecules that have the ability to complex small cations, notably alkali metals such as sodium and potassium. These cyclic molecules, upon complexing a cation, can allow a salt to go into organic solvent that otherwise wouldn't.
Sorry for the short updates this week! Chloranil is an oxidizing agent. Part of its usefulness comes from its solubility in organic solvent, which you don't see with things like permanganate or H2O2.
Meat production stinks.  And I’m not referring to worries about bacterial contamination.  I mean it literally stinks.  Here’s the story.  Hold your nose.
Normally, iodine just makes one bond, as you'd expect from a halogen. Some compounds, though, force it into lively higher oxidation states (hopefully without the tendency to explode, as some highly oxidized iodine reagents worryingly exhibit).

Permanganate I've never really seen used in a real research laboratory - although I do remember the bright violet colour of a dilute solution in the school labs. It's too strong for general use and tends to chew everything up. Great oxidiser though. Other choices are the chromates (potassium dichromate), which are a bit more selective.

Your suggestion of crown ether complexation could give a more useable oxidant and one that can be used in organic environments, which would probably decrease it's power a bit too.