Phosphonate derivatives, calixarenes

Phosphonito (5.390a), phosphinito (5.390b) and phosphonate (5.390c) calixarene-[4] derivatives and other P-containing cavitands have been prepared [190-195]. Some of these compounds are useful as catalysts and others are possible metal extractants [196]. 

In the phosphorus(V) acids area, there has been continued interest in the preparation of phosphates from elemental phosphorus, and also of compounds derived from the calixarenes. Apart from these, there has been little of real significance in the phosphate field. A much greater interest has been shown in enantio- or diastereo-selectivity in synthesis and reactivity of phosphonates and... 

Several reports in the literature show that calixarene derivatives play a crucial role in controlling the size and stability of MNPs [106-108]. For example, Raston reported on the synthesis of p-phosphonic acid calix[8]arene-modified Ru, Pt and Pd nanoparticles in aqueous solution (Fig. 37.16) [109]. The macrocycle was demonstrated to exert a control over the shape and size of the produced nanoparticles by acting as stabilizing agent. Molecular modeling revealed that 12 molecules of the macrocycle surround 2-nm Ru particles, where a H-bonding network among calix[8]arenes contribute to the interfacial self-assembly. 

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