Operating Molecular Elevators
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- 作者：Jovica D. Badjic ; Cé ; lia M. Ronconi ; J. Fraser Stoddart ; Vincenzo Balzani ; Serena Silvi ; and Alberto Credi
- 刊名：Journal of the American Chemical Society
- 出版年：2006
- 出版时间：February 8, 2006
- 年：2006
- 卷：128
- 期：5
- 页码：1489 - 1499
- 全文大小：514K
- 年卷期：v.128,no.5(February 8, 2006)
- ISSN：1520-5126
文摘
Inspired by the concept of multivalency in living systems, two mechanically interlocked moleculeshave been conceived that incorporate not once or twice but thrice the features of a pH-switchable [2]rotaxanewith two orthogonal recognition sites for dibenzo[24]crown-8 (DB24C8), and 2,3-dinaphtho[24]crown-8(DN24C8)-one a dialkylammonium ion (CH2NH2+CH2) and the other a bipyridinium dication (BIPY2+).Whereas at low pH, the CH2NH2+CH2 sites bind the DB24C8/DN24C8 macrocycles preferentially, at highpH, deprotonation occurs with loss of hydrogen bonding and the macrocycles will move to the BIPY2+sites, where they can acquire some stabilizing [
-] stacking interactions. Such mechanically interlockedmolecules have been assembled from a trifurcated rig-like component wherein the dumbbell-like componentsof three [2]rotaxanes have one of their ends fused onto alternate positions (1,3,5) around a benzenoidcore. The rig is mechanically interlocked by a platform based on a tritopic receptor, wherein either threebenzo[24]crown-8 or three 2,3-naphtho[24]crown-8 macrocycles are fused onto a hexaoxatriphenylene core.The synthesis of these molecular elevators involves 1:1 complexation, followed by stoppering, i.e., feetare added to the rig. 1H NMR spectroscopy and cyclic voltammetry, aided and abetted by absorptionspectroscopy, have been employed to unravel the details of the mechanism by which the rig and platformcomponents move on the alternate addition of base and acid. For each molecular elevator, the platformoperates by taking three distinct steps associated with each of the three deprotonation/reprotonationprocesses. Thus, molecular elevators are more reminiscent of a legged animal than they are of passengerson freight elevators.
-] stacking interactions. Such mechanically interlockedmolecules have been assembled from a trifurcated rig-like component wherein the dumbbell-like componentsof three [2]rotaxanes have one of their ends fused onto alternate positions (1,3,5) around a benzenoidcore. The rig is mechanically interlocked by a platform based on a tritopic receptor, wherein either threebenzo[24]crown-8 or three 2,3-naphtho[24]crown-8 macrocycles are fused onto a hexaoxatriphenylene core.The synthesis of these molecular elevators involves 1:1 complexation, followed by stoppering, i.e., feetare added to the rig. 1H NMR spectroscopy and cyclic voltammetry, aided and abetted by absorptionspectroscopy, have been employed to unravel the details of the mechanism by which the rig and platformcomponents move on the alternate addition of base and acid. For each molecular elevator, the platformoperates by taking three distinct steps associated with each of the three deprotonation/reprotonationprocesses. Thus, molecular elevators are more reminiscent of a legged animal than they are of passengerson freight elevators.