Calixarenes modified

Voltammetric behavior in trace determination of cadmium at a calixarene modified screen-printed carbon paste electrode was investigated [405]. 

Calixarenes modified with a reporter site are equally competent chemosen-sors for the detection of a variety of analytes according to Scheme 6, especially when the analyte is cationic. The tt-cavity of a tetraanionic resorcin[4]arene readily binds cationic guests, a feature that Inouye et al. have exploited in the development of an acetylcholine chemosensor [358], The fluorescence from a pyrene-modified N-alkylpyridinium is strongly quenched upon its association with the tetraphenolate form of resorcin[4]arene (24). This quenching is consis-... 

In nonpolar media, complexes with calixarenes modified with phosphine and phosphite groups have been used in hydroformylation [219,220]. Bagatin et al. [221] and Fang et al. [222] described the successful use of the diphenylphos-phinated calixarenes 80-81 in hydroformylation of styrene and 1-octene. 

S.J., and McKervey, M.A. (1992) Stripping voltammetry with a polymeric calixarene modified carbon paste electrode. Anal Proc., 29, 27-29. 

Li reported the first synthesis of calixarene-modified chitosan. The adsorption properties of calixarene-modified chitosan were greatly varied compared with that of chitosan, especially with the adsorption capacity towards Ag and Hg, becanse of the presence of calixarene moiety (Li et al., 2003). Pyravic acid modified chitosan had higher adsorption capacities for Cu + Co than chitosan and salicylalde-hyde modified chitosaa Chitosan benzoyl thiourea derivative has been synthesized and used successfully for the removal of the hazardous Co and Eu radio nuclides from aqueous solutions (Metwally et al., 2009). 

Fig. 2.1 Peptidocalixarenes calixarenes modified at upper rims with peptides connected through (a) the W-terminus (b) the C-terminus...

Fig. 2.10 Examples of calixarenes modified with chiral amines and their metal complexes...

Combining the supramolecular host-guest properties of calixarenes, the optical properties of calixarene-modified CdSe/ZnS semiconductor QDs were controlled for the optical detection of neurotransmitter (acetylcholine), Ceo and mercury ions [65-70]. SC[4,6]A was selected to prepare highly fluorescent, stable and water-soluble CdSe QDs by simple, rapid ligand exchange route [71]. Then, this kind of QDs were used to construct Au electrode with enhanced photocurrents systems. [72] CdTe QDs in silica spheres coated with calix[4]arene were also synthesized as luminescent probes for pesticides and PAHs [64]. 

SAMs of calixarene derivatives have been demonstrated to possess recognition properties towards ions [69-77] and small organic molecules [78-83]. For example, in 2012 Li reported on calix[4]azacrown-based SAMs that exhibit ion-pair recognition properties towards l-butyl-3-methylimidazolium chloride [84], The calixarene-based SAM was produced by a click reaction between the azido-modified silicon substrate and the calix[4]azacrown. The authors demtmstrated by contact angle (CA) measurements that the calixarene-modified surface is superhydrophobic (CA= 154.6 3°). Upon immersion of the calixarene-based SAM in a l-butyl-3-methylimidazolium chloride solution, the CA drops to 10.1 3° (Fig. 37.14). On the other hand, no changes in the CA of the surface are observed in the presence of 1-butyl-3-methylimidazolium bromide and l-butyl-3-methylimidazolium hexafluorophosphate. The calix[4]azacrown modified SAM was therefore demonstrated to possess selective wettability response towards the l-butyl-3-methylimidazolium chloride ion-pair. 

The use of arachidic acid and different amphiphilic calixarenes for modifying of field effect transistor sensors and determination of some volatile organic contaminants will be considered. 

The smaller p -tert-butyl-calix [4] arenes have a rich coordination chemistry as well (65). Of these, however, only the upper-rim modified calixarenes seem to support metal complexes with confined binding sites (66), except in those cases where the lower-rim substituents form an appended cavity. Thus, Matt and coworkers have reported (67) a pocket-shaped calix[4]arene ligand L2 bearing two lower-rim [([Pg.410]

Based on the theory, the separation of enantiomers requires a chiral additive to the CE separation buffer, while diastereomers can also be separated without the chiral selector. The majority of chiral CE separations are based on simple or chemically modified cyclodextrins. However, also other additives such as chiral crown ethers, linear oligo- and polysaccharides, macrocyclic antibiotics, chiral calixarenes, chiral ion-pairing agents, and chiral surfactants can be used. Eew non-chiral separation examples for the separation of diastereomers can be found. 

Water-soluble calixarenes are more and more investigated in order to make use of their ability to host other molecules, and the first examples of the use of phosphine-modified calixarenes in organometallic catalysis appeared just recently. Rhodium complexes prepared with 197 (Figure 19)... 

G.A. Evtyugin, I.I. Stoikov, C.K. Budnikov and E.E. Stoikova, A cholinesterase sensor based on a graphite electrode modified with 1,3-disub-stituted calixarenes, J. Anal. Chem., 58 (2003) 1151-1156. 

The structure of the tetranitro derivative was confirmed by X-ray diffraction in the solid state, this compound does not possess any symmetry element. The conformation of the calixarene structure is less symmetrical than for calix[4]arene(bis crown-6). The nitro groups appear to strongly modify the usual conformation of this calixarene, and a decrease in the preorganization toward cesium complexation can be expected. 

Choice of a Phase Modifier for Calixarene Crown-6 Diluted in Aliphatic Hydrocarbon Diluents... 

In the previous studies, calixarenes were not directly usable in a liquid-liquid extraction process, because used in a diluent (nitro phenyl hexyl ether), the hydrodynamic properties were incompatible with such a process. The system has been modified in order to satisfy the following criteria density, viscosity, kinetics, and absence of a third phase.102... 

Two systems based on crown-calixarenes, able to be used in liquid-liquid extraction process were chosen. Both systems use a modifier in the organic phase to avoid the occurrence of a third phase in the TPH (diluent used at the reprocessing plant of la Hague for the PUREX process) and ensure a sufficient cesium extraction. 

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