The Best Amphiphilic Bistable Rotaxane-based Device to Date

7 The Best Amphiphilic Bistable Rotaxane-based Device to Date 

In the most recent iteration of the feedback loop which relates molecular structure to solid-state device performance, the fast bistable [2]rotaxane 11 has been superseded by the modified and improved version shown in Fig. 1.15, namely, the [2]rotaxane The impetus for this iteration was at least two-fold (1) to produce a molecular switch in which the bistable rotaxane starts off exclusively in one, and only one, of its two possible co-conformations and (2) to incorporate into this all-or-nothing switch enhanced oxidative stability by removing all of the phenolic residues from the hydrophilic stopper. The rotaxane, which was obtained (Fig. 1.15) by the now well-established templation protocol, has been incorporated by the familiar fabrication procedures into an 8 x 8 crossbar device (Fig. 1.16(a)). Fig. 1.16(b) demonstrates one of these 64-bit devices in operation with the exception of one of the wires, i.e., 56 out of the 64 bits can be switched. This device has been used to store (Fig. 1.16(c)) the letters DARPA in ASCII code the lifetime of the switch-closed state of this devices is about 10 minutes. The proposed electromechanical switching mechanism for the bistable [2]rotaxane which is outlined in Fig. 1.17, merits comparison with that already discussed in Fig. 1.16 for the bistable [2]rotaxane In the case of it is proposed that oxidation of the TTF unit to its radical cation (TTF ) occurs when a +2 V bias is applied across the bistable [2]rotaxane and the tetracationic cyclophane moves to encircle the 

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