Magician's trick rings and the olympic symbol are both visually similar to pictures of catenanes. These molecules
are interlocked rings (or chains - thus catenane from catena). Two rings joined together are a [2]catenane, which is probably the easiest to make (and draw) :
_______________ _______________
| _____________ | | _____________ |
|| || || ||
|| || || ||
|| OPEN || _|_ || CLOSED ||
|| || | || ||
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_____________ || ||
|_____________| ||_____________||
|_______________|
_____________
| ___________ |
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|| ||
|| ||
|| _____||______
|| | ____||_____ |
|| || || ||
______||_____ ||
|______||_____| || OVERLAPPING
|| ||
|| ||
||___________||
|_____________|
_____________
| ___________ |
|| ||
|| ||
|| ||
|| _____||______
|| | ____||_____ |
|| || || || CATENATED
||_____||____|| ||
|______||_____| ||
|| ||
|| ||
||___________||
|_____________|
The '
bond' between the two rings is
topological - that is, there is not necessarily any direct contact or
electron sharing, but they cannot be separated except by breaking one of the rings (or by magic :). However, many catenane sytheses have relied on pi-pi stacking interactions between aromatic groups. An extreme example of a catenane is
Olympiadane which, as it's name suggests, is a [5]catenane.