Calixarenes applications

Apart from the above-described established areas of calixarene applications, several very interesting new fields have been opened in recent years, which all rely on calixarene-DNA interactions. 

Applicability in biological ion assay is an important factor for biocompatible potentio-metric ion sensors. Attempts were made to determine Na" " concentrations in human blood sera by using silicone-rubber membrane Na+-ISFETs based on (5) [Fig. 17(a)] [29]. The found values for Na concentration in undiluted, 10-fold diluted, and 100-fold diluted serum samples are in good agreement with the Na" " calibration plots. Even in the undiluted serum samples, only a slight potential shift was observed from the calibration. This indicates that the calixarene-based silicone-rubber-membrane Na+-ISFETs are reliable on serum Na assay. For comparison with the silicone-rubber membrane, Na -ISFETs with corresponding plasticized-PVC membrane containing (2) or (5) were also tested for the Na assay. The found values of Na" " concentration... 

The examples summarized in Table 5 and in Sect. 5 of this review illustrate the applicability of RCM to the preparation of various macrocyclic perfume ingredients [30], pheromones [30], antibiotics [31-35], crown ethers [36], cyclic peptides [37],catenanes [38] and capped calixarenes [39]. 

After the separation of the actinides from the high-level waste, it is desirable to remove certain other fission products from the nuclear wastes. Some Cs and Sr are low-charged cations that react well with macro-cyclic ligands (e.g., crown ethers, calixarenes). Research to synthesize and investigate the properties of macrocyclic ligands for application in nuclear waste treatment has been an active effort internationally. Some of the results obtained are discussed in section 12.7. 

With the increasing demand for chiral nonracemic compounds, stereoselective methods for the synthesis of 1,3-oxazine derivatives and applications of enantiopure 1,3-oxazines in asymmetric transformations have gained in importance in the past decade, as reflected by the increasing trend in the number of publications on this topic, and accordingly by the share of this topic in the present compilation. The limited size of this survey and the scope of this chapter do not allow a discussion here of the applications of 1,3-oxazines in polymer chemistry and the synthesis and properties of 1,3-benzoxazine-containing hetero-calixarenes. 

Haverlock, T. J., Bonnesen, F. V., Sachleben, R. A., Moyer, B. A., Applicability of a calixarene-crown compound for the removal of cesium from alkaline tank waste, Radiochim Acta, 76,103-108,1997. 

Although fluorescent calixarenes would be an appropriate section herein, especially as regards nuclear applications, the reader is referred to the recent and exhaustive review Calixarene-derived Fluorescent Probes. 85... 

The explosion of supramolecule architectures makes the elaboration of new receptors an obvious target of future investigation. Buckets are endpoints of a continuum of supramolecules based on rings and other cylindrical structures [413], These related macromolecules demonstrate bucket-type, lock-and-key interactions that are similar to those of CDs and calixarenes. The unique physical and chemical properties of the different supramolecule reporter sites enable the selectivity and sensitivity of analyte recognition to be exquisitely tuned. Depending on the analyte and the application, it is likely that new supramolecule architectures will be the cornerstones of many new chemosensor platforms. 

The parent / -f-butylcalix[n] arenes (n = 4, 6, 8) are almost completely insoluble in water. However, their resemblance to crown ethers and spherands makes them interesting from the point of view of applications as phase transfer catalysts (Section 3.8.2). Table 3.20 shows the selectivity of calixarene 3.118 and its hexameric and octameric homologues for the extraction of various metal hydroxides into an organic receiving phase such as chloroform. Fortunately, in aqueous base the calixarenes are sufficiently soluble to act as phase transfer catalysts as a consequence of deprotonation of one of their phenolic hydroxyl groups. This solubility contrasts to [18] crown-6, which is much more effective in neutral solution. 

Shinkai, S., (1990) Functionalization of crown ethers and calixarenes new applications as ligands, carriers, and host molecules Bioorg. Chem. Front. 1, 161-195. 

Schatz, J. (2004) Recent application of ab initio calculations on calixarenes and calixarene complexes. A review, Coll. Czech. Chem. Comm. 69, 1169-1194. 

Meanwhile, cation - crown complexes were fully optimized by ab initio QM techniques in the gas phase, allowing to investigate the effect of electronic reorganization (mainly charge transfer + polarization effects) on the recognition properties/15,161 QM/MM hybrid methods which combine a QM representation of the ion coordination sphere with a MM representation of the more remote species, have been tested on 18C6/ cation complexes/17, 18] Typical applications of "computational approaches in supramolecular chemistry" up to 1994 can be found in ref. [191 There are also reviews on more specialized fields like calixarenes/20,21]... 

Among more complex macrocycles, Li et al. [47-52] reported the preparation and characterization of stationary phases incorporating calixarenes or calix-crowns bonded to silica. With individual columns, high selectivity was observed in the separation of alkylated aromatics, aromatic carboxylic acids, sulfonamides, nucleosides, and water-soluble vitamins. In other work, Sokoliess et al. [53] have characterized calixarene- and resorcinarene-bonded stationary phases similar to those described in the previous section of this chapter. And Huai et al. [54] used an end-capped p-tert-butyl-calix[4]arene-bonded silica phase for HPLC separation of a number of organic compounds. Resorcinarenes have also found application in GC. [55-57] Recently, exotic macrocycles have been used in capillary electrochromatography, as reported by Gong et al. [58]... 

Alexandratos, S. D. and Natesan, S. (2000) Coordination Chemistry of Phosphorylated Calixarenes and their Application to Separations Science, Ind. Eng. Chem. Res. 39, 3998-4010. 

Abstract Calix[n]arenes represent a well-known family of macrocyclic molecules with a broad range of potential applications in many branches of supramolecular chemistry. Because of their preorganisation, calix[n] arenes are frequently used as building blocks and molecular scaffolds in the construction of more elaborate systems, such as artificial enzyme biomimetics and receptors. This review is focused on the recent development of calixarene-based anion receptors. 

While the selective interactions of functionalised calixarenes with cations have been studied broadly for almost three decades, the application of cal-ixarene-based receptors for anion recognition is a relatively new research topic [2]. This review is focused on recent developments in the design and synthesis of calixarene-based anion receptors. Although the name calixarene was originally designated only for phenol-formaldehyde derivatives 1, recently many structural variations and mutations have been formed. Some of them, such as calixpyrroles [3], are widely used for anion recognition nevertheless, this review is restricted only to classical calixarenes 1 and newly discovered thiacalix-arenes 2 [4]. 

Consequently, the application of calixarene as a molecular scaffold allows the design of receptors utilising the combination of spatially oriented hydrogen bonds (HBs) and synchronous coulombic interactions. Of course, both factors favourably influence the overall complexation process. The role of preorganisation can be illustrated by the comparison [9] of calixarene 3 with acyclic analogue 4. 

A fulleropyrrolidine derivative has been synthesized and covalently linked to HPLC silica gel and the resultant material was used to separate calixarenes, cy-clodextrins, and protected peptides [271]. Another type of organofullerene material containing polysiloxane was recently synthesized. It was found to be suitable for separating high-boiling-point compounds, and can be found applications as the stationary phase in capillary gas chromatography [272]. 

---