![]() ![]() ![]() In 1998 Davis pointed out that occurrence of the desired behavior of the molecular ratchet would have constituted a violation of the second law of thermodynamics (Davis, 1998). Kelly and coworkers designed an elegant experiment to determine whether their molecular ratchet was functioning as anticipated, and they were (presumably) disappointed to find that it was not-internal rotation about the A-B bond occurred at equal rates in each direction. ![]() Thus, in some sense, this might be an inverse ratchet where the asymmetry dictating the sense of rotation would reside in the pawl rather than in the “teeth” on the “wheel” (the triptycene unit) as it does in a normal mechanical ratchet. The reason for thinking this might occur was that the benzophenanthrene moiety-the “pawl” of the ratchet-was anticipated to be helical. It was designed to be a “molecular ratchet,” so named because it appeared that it should undergo internal rotation about the A-B bond more readily in one direction than the other. They had synthesized the molecule shown in figure 12.1. In 1997, Ross Kelly and his coworkers at Boston College reported their results from an experiment with an intriguing premise (Kelly et al., 1997 see also Kelly et al., 1998). ![]()
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