Calixarenes in Molecular Recognition

Abstract

This chapter summarizes the most important aspects of the chemistry of calixarenes and their applications in supramolecular chemistry. The first section gives a short summary of the synthesis and conformational properties of calixarenes and of their functionalization at the phenolic OH groups ( lower rim ) and at the para‐position of the aromatic nuclei ( upper rim ). The second section covers the properties of native and functionalized calixarenes (including chiral compounds) as receptors for the selective recognition of neutral molecules, cations, anions, and ion‐pairs in the solid state, organic media, and water solution. In the third section, the calixarenes are viewed as scaffolds for the construction of multivalent ligands able to target biomacromolecules eliciting or inhibiting a biological process. Calixarene glycoclusters, operating as efficient and selective multivalent inhibitors of vegetal and mammalian lectins; peptidocalixarenes, capable of disrupting protein–protein interactions; and guanidino‐calixarenes, able to target proteins or to condense DNA, acting, in this case, as efficient nonviral vectors for cell transfection, are discussed. When relevant, the use of calixarene receptors and multivalent ligands as active components of sensor devices for the detection of various analytes is also reported. Perspectives for future developments of calixarenes in supramolecular chemistry and bionanotechnology are indicated.

Calixarene-engineered surfaces and separation science

“…A series of books and reviews have been published which discuss in length the calixarenes and its substituted derivatives being used for the recognition of cation, anion, neutral molecules, and organic compounds [6][7][8][9][10][11]. Reversible interaction of calixarenes with different types of solutes and their adaptability to various applications made this group of supra-molecules very popular in sorption and chromatography as sorbent or stationary phase [12].…”

Amino Acid‐Functionalized Calix[4]Resorcinarene Solubilization by Mono‐ and Dicationic Surfactants

“…Increasing interest and attention to this group of macrocycles have been caused by the many opportunities they open in designing supramolecular assemblies [2,3]. The ability to form ''guest-host'' complexes allows one to create a series of highly selective sensors [4], extracting agents [5], high-efficient catalytic systems [6,7], and may have prospective impact on nanomedicine and healthcare [8]. Some advances in biomedical applications of calixarenes, e.g.…”

“…enhance biocompatibility and the demonstration of the specific biological effects [16,17]. Recently, we have reported syntheses of calix [4]resorcinarenes containing glycine (CR-Gly) [18] and alanine (CR-Ala) or valine (CR-Val) [17] residues at the upper rim. However, their use in aqueous solutions including almost all biological fluids, are limited because of extremely low solubility in water being less than 1 lM.…”

“…However, their use in aqueous solutions including almost all biological fluids, are limited because of extremely low solubility in water being less than 1 lM. Despite the fact that the amino acids are zwitter-ions in water and therefore are polar, it often does not increase the solubility enough to make hydrophobic and bulky functionalized calix [4]resorcinarene macrocycle water-soluble. The problem of low solubility of the CR-Ala and CR-Val in water can be resolved by solubilizing them in surfactant micelles resulting in the surfactant/calix [4]resorcinarene aggregate formation.…”

“…Despite the fact that the amino acids are zwitter-ions in water and therefore are polar, it often does not increase the solubility enough to make hydrophobic and bulky functionalized calix [4]resorcinarene macrocycle water-soluble. The problem of low solubility of the CR-Ala and CR-Val in water can be resolved by solubilizing them in surfactant micelles resulting in the surfactant/calix [4]resorcinarene aggregate formation. This approach has been successfully applied to increase the solubility of non-polar organic compounds in water [19].…”