Molecular Machine
A model of the Pauling principle - catalysis by maximum binding to the transition state – was devised in 1978. A physical processes, the racemization of the bipyridyl shown below was chosen. The transition structure features coplanar aryl rings and a binding force — the chelation of a metal by bipyridyl —shows maximum metal/ligand attraction at the coplanar geometry. The biaryl bond acts like a fulcrum and binding induces a mechanical stress elsewhere in a molecule. This was one of the first molecular machines, a rotor.
Read more about this topic: Julius Rebek
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