Bridged calixarenes intermolecular

Two calix[4](diseleno)crown ethers were synthesized by the treatment of the disodium salt of 1,3-propanediselanol with preorganized 1,3-dibromoethoxycalixarenes the 1,3-Se-bridged calixarene forms an infinite sheet aggregate by means of self-inclusion and intermolecular Se—Se interactions in the solid state <02TL131>. 

As polyhydroxy compounds, calix[w]arenes can be reacted with multifunctional electrophilic reagents not only inter- but also intramolecularily. Some di- and multicalixarenes as examples of intermolecular reactions are reported in Section VUI. Intramolecular (i.e. bridging) reactions have been used to rigidify the calixarene skeleton, to protect hydroxy groups and to create ligands for metal cations, which in many cases show an unprecedented selectivity. 

Compound 200e provides one example in which a pair of calixarenes are intermolecularly joined by a pair of upper rim to lower rim bridges. Other examples of upper rim to upper rim bridging are illustrated by (a) 215a, obtained in 48% yield by treating p-A,C-bis(hydroxymethyl)calix[4]arene with p-A,C-bis(chloromethyl)calix[4]arene in the presence of (b) 215b and... 

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