Calix arenes carbonyl functionalized

Cation Interaction with Carbonyl Functionalized Calix[4]arenes... 

ISEs and CHEMFETs with calix[4]arene 32, bearing two thioether functionalities, are highly selective for Ag+ in the presence of alkaline earth ions (K" ", Ca ) and transition metal ions (Cu, Cd ), with selectivities log/f gj varying from —4.2 to —4.7 [133,135]. The CHEMFETs with 32 also showed selectivity for Ag in the presence of Hg " " ions (log g g = —2.7), which is quite unique since both ions have the same coordination number and preference for a linear interaction with soft donor atoms [133]. McKervey et al. reported Ag selectivity for calix[4]arene 33 in PVC membrane based ISEs [136]. These ISEs show a moderate Ag" selectivity (—1.1 to -2.1). Due to the presence of the hard donating carbonyl atoms in the molecule, a sub-Nemstian response (50mV decade ) was obtained in the presence of alkaline metal ions [137]. Moreover, the sensor was not selective for Ag in the presence of Hg " ions. 

The cyclic tetramer of p-t rf-butylphenol-formaldehyde condensates which maintains a cone-type conformation called a calix[4]arene from its cuplike shape, similar to that of a Greek crater vase, tends to complex with small organic compounds or metal ions. Further, incorporation of carbonyl groups such as ester, amide and ketone linkages into the phenolic oxygen atoms of the calixarene makes it function as an ionophore [1]. 

Figure 9.11 Temperature probe desorption experiments of calix[4]arene phosphine-lr4 carbonyl clusters as a function of electron richness. Electron richness decreases moving from left to right on thex-axis [15],...

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