Trapezoidal macrocyclics

This figure was generated using data provided by Sessler and Vogel, et al. The core nitrogen atoms define a regular trapezoid. The molecule is nearly planar (the maximum deviation from the mean macrocyclic plane is 0.14 A) and the cobalt atom sits directly within the mean macrocyclic plane. 

Figure 6.6 Trapezoidal macrocycles prepared by Claisen-Schmidt condensation of one flexible female-female connector with a flexible male-male connector. (Macrocycle 27 crystallizes as a hydrate with a hydrogen-bonded bridging water molecule between the phenolic moieties.)...

Isoaromatization of dienone macrocycles afforded Horning-crown macro-cycles - flexible macrocycles bearing structural elements reminiscent of those found in both calixarenes and crown ethers. In some cases the Horning-crown macrocycles exhibited solvent-dependent and switchable conformations. For macrocycles with the same short linker, self-complementarity was observed, and dimers tended to crystallize as solvates or inclusion compounds. This tendency was suppressed with longer linkers and in some Horning-crowns derived from trapezoidal macrocycles. These properties suggest potential applications in analysis, separation and detection (Figure 6.8). ... 

Figure 6.8 (a) Trapezoidal Horning-crown macrocycles with flexible tethers such as 28... 

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