Anion receptors calixarene

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]. 

Another interesting and potentially very useful group of calixarene-based anion receptors is represented by systems with appended transition metal complexes of 2,2-bipyridine units. Technically, these systems utilise classical hydrogen bonding interactions of amidic/urea functions hence, from this point of view, they do not differ from many other receptors. On the other hand, the covalent attachment of bipyridine complexes of ruthenium(II) or rhe-... 

Another class of metal-employing anion receptors is represented by structure 24 [23]. Its function is based on the incorporation of positively charged transition metal complexes directly into the calixarene skeleton. Such calixarenes with enhanced electron deficiency of the aromatic walls provide well-preor-ganised cavities suitable for anion inclusion. The corresponding rhenium [24], ruthenium, rhodium or iridium complexes of this type were prepared and studied for anion recognition [25,26]. 

Several calix[4]arene [54, 55] or calix[6]arene [56, 57] derivatives 42-44 bearing ureido or thioureido functions on the lower rim have also been evaluated as anion receptors. As indicated by NMR spectroscopy, calixarene 42... 

Lhotak, P. (2005) Anion Receptors Based on Calixarenes" in Anion Sensing, (Topics in Current Chemistry) (ed. Stibor, J.), Springer, Heidelberg, 255, 65—95. 

Leiserowitz L, see Weissbuch I (2005) 259 123-165 Lhotak P (2005) Anion Receptors Based on Calixarenes. 255 65-95 Li WP, Meyer LA, Anderson CJ (2005) Radiopharmaceuticals for Positron Emission Tomography Imaging of Somatostatin Receptor Positive Tumors. 252 179-192 Liang Z, see Du Q (2005) 261 45-61 Lingerfelt L, see Guiseppi-Elie A (2005) 260 161-186... 

S. E. Matthews and P. D. Beer, Calixarene-based Anion Receptors, in Reference lb, p. 421. A. Arduini, A. Pochini, A. Secchi and F. Ugozzoli, Recognition of Neutral Molecules,in Reference lb, p. 457. 

Progress of calixarenes used as anion receptor 06CJO419. 

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