71-71 interaction stacking

SCHEME 17.5 Methodology developed by Sanders et al. for high yield chemical knotting of electron poor dialkynes (light grey) in cavity of electron-rich bisnaphthalene (dark gray) forming a [2]catenane. H atoms are omitted for clarity. (Adapted from CCDC 182443.), 33 

This example clearly demonstrates that multiple weak n-stacking interactions can be combined synergistically to obtain strongly pre-organized precursors allowing for the knotting steps to be performed with high chemical yields. 

---

The pentafluorophenyl group imparts greater crystallinity to the complexes and as a result many complexes have been studied by X-ray crystallography. Although vith other metal centers C Fs-CaFs or CfiFs-CfiHs n-n stacking interactions are observed [21, 22], there are not many examples in gold chemistry and they have been sho vn very recently [23]. 

This catalyst induces preferential re facial attack on simple aldehydes, as indicated in Ligure 2.2. The enantioselectivity appears to involve the shielding of the si face by the indole ring through a ir-stacking interaction. 

Fig. 1 The w-stack of double helical DNA. In this idealized model of B-DNA the stack of heterocyclic aromatic base pairs is distinctly visible within the sugar-phosphate backbone (schematized by ribbons) a view perpendicular to the helical axis b view down the helical axis. It is the stacking of aromatic DNA bases, approximately 3.4 A apart, that imparts the DNA with its unique ability to mediate charge transport. Base stacking interactions, and DNA charge transport, are exquisitely sensitive to the sequence-depen-dent structure and flexibility of DNA...

---