Calixarenes, Cyclodextrins, Molecular Sieves and Boxes

The potential applications of calixarmes range from molecular hosts for sensor techniques and medical diagnostics, use in decontamination of wastewater, construction of artificial enzymes, new materials for nonlinear optics to sieve membranes with molecular pores. 

Early reports on AFM studies on calix[4]resorcinarene and calix[4]arene sulfide molecules [150, 151], suggested, that the calixarenes self-organize in monolayers on Au(lll) surfaces, however, they did not identify a molecular ordering. 

Bai and co-workes reported a series of STM studies on various types of calixarenes on graphite and Au(lll) surfaces. Initially, they included p-tert-butylcalix[8]-arene in between domains of octa-alkoxyl-substituted phthalocyanine (PcOCg) monolayers on graphite [152]. The adsorption of calix[4]arene (lower rim OH) on (111) facets of Au-beads lead to an edge-on geometry of calixarene dimers with the lower rim pointing towards lower rim (Fig. 10.26a) [153]. 

On the other hand, deposition of calix[4]arene (lower rim propyl, upper rim COOH) again on (111) facets of Au-beads - this time under potential control -resulted in presumably face-up (upright) adsorbed monolayers (Fig. 10.26b) [154]. 

Calix[8]arene OBOCMC8 (C104H128O24) and the inclusion complex C60/ OBOCMC8, both adsorbed face-up on the (111) facets of Au-beads (Fig. 10.26c) [155]. 

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