Molecular structure cyclophane

The 10-membered ring cyclophanes 183-185 are novel compounds bearing unique molecular structures (Figure 44) <2006JOC6110>. 

Stoddart and co-workers have developed molecular switch tunnel junctions [172] based on a [2]rotaxane, sandwiched between silicon and metallic electrodes. The rotaxane bears a cyclophane that shuttles along the molecular string toward the electrode and back again driven by an electrochemical translation. They used electrochemical measurements at various temperatures [173] to quantify the switching process of molecules not only in solution, but also in self-assembled monolayers and in a polymer electrolyte gel. Independent of the environment (solution, self-assembled monolayer or solid-state polymer gel), but also of the molecular structure - rotaxane or catenane - a single and generic switching mechanism is observed for all bistable molecules [173]. 

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loop which relates molecular structure to solid-state device performance, the fast bistable [2]rotaxane 11" has been superseded " by the modified and improved version shown in Fig. 1.15, namely, the [2]rotaxane The impetus for this iteration was at least two-fold (1) to produce a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... 

Figure 14.21. Molecular structure and atoms numbering of the hexaaza-cyclophane Cu(II) complex. Reprinted by permission of Elsevier B.V.

Triazolophanes Cyclophanes with an array of molecular structures and supramolecular architectures 12IJC92. 

Thiacyclophanes have attracted interest not only as useful intermediates in the synthesis of cyclophanes and annulenes, but also for their stereochemical > and mass spectral behaviour. The synthesis of new thiacyclophanes " utilized established methods, and JiT-ray analysis provided a convenient method of determining their crystal and molecular structure. ... 

Fig. 40 Molecular structure of oligo(thiophene) (60) and cyclophane (61) based organo-gelators...

Figure 6.5. Molecular structure (a) and solid-state structure of helical cyclophane 25 (b).

Figure 6.7. Molecular structure (left) and solid-state structure (right) of helical cyclophane 69.

Cyclophanes or 7r-spherands have played a central role in the development of supramolecular chemistry forming an important class of organic host molecules for the inclusion of metal ions or organic molecules via n-n interactions. Particular examples are provided by their applications in synthesis [80], in the development of molecular sensors [81], and the development of cavities adequate for molecular reactions with possible applications in catalysis [82]. The classical organic synthesis of cyclophanes can be quite complex [83], so that the preparation of structurally related molecules via coordination or organometallic chemistry might be an interesting alternative. 

When Illb is heated with p-phenylenediamine at 200-300°C under conditions similar to the other phenylenediamines, mainly insoluble, probably crosslinked, oligomers (rubber-like solid) are formed. On the other hand, p-phenylenediamine with bis(diethylamino)dimethylsilane at 180°C yielded a toluene-soluble solid whose molecular weight and elemental analysis agree well with the probable cyclophane structure IX for C32H48NsSi4 Mcaic. 657.16, found Mcryoscopic 648, m/e 657.16 calc. % C, 58.49 H, 7.36 N, 17.05 Si, 17.10 found % C, 58.40 H, 7.42 N, 17.10 Si, 17.16. The structure of this compound is being further investigated. 

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