Koilands noncentrosymmetric

Figure 12 Structures of discrete tetranuclear inclusion self-inclusion complexes formed by noncentrosymmetric koilands 17 with EtOH (a) and 21 with THF (b). For the sake of clarity, hydrogen atoms are not represented.

In solution, as expected, 29Si NMR studies revealed the presence of two signals for all noncentrosymmetric heterodimers, whereas for the centrosymmetric koilands a unique signal was observed. 

For the geometrically differentiated noncentrosymmetric koiland 22 based on the double fusion of the p-tert-butyl calix 5 and p-allyl calix unit 6 by two Si atoms, the formation of directional koilates was studied using p-xylene 31 as a centrosymmetric (Figure 4g and h) and phenylpropyne 34 as a noncentrosymmetric (Figure 4f) connectors [81]. 

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