A question recently asked here whether compounds know to be chiral can have non-measurable optical rotations: Are there chiral compounds that don't rotate plane-polarized light?.

Apparently they exist and the phenomenon is known as cryptochirality.

This prompted me to think of the opposite end of the spectrum of optical rotation. Which known compound shows the largest known optical rotation?

NB when I say "known compound" I mean something that has actually been synthesised in large enough quantities to be well characterised. So no theoretical-only compounds or esoteric systems.

  • $\begingroup$ One aspect which might make this tricky is that many publications are awful at using the correct units for specific rotation, meaning values are often ambiguous. $\endgroup$ Oct 16, 2018 at 23:58
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    $\begingroup$ Various helicenes are said to have rather high specific optical rotations. What about switchable one from “low” rotation to high, is |[α]|=4680° enough? :−) $\endgroup$
    – mykhal
    Oct 17, 2018 at 0:09
  • 1
    $\begingroup$ Maximum observed optical rotation through a polarimeter might come handy, if someone approches the question practically $\endgroup$
    – mykhal
    Oct 17, 2018 at 0:30


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