Homocalixarenes

Crystal Structures of Uranyl Ion Complexes of Tetrahydroxy[3.1.3.1]metacyclophane (Homocalix[4]arene)

“…Homocalixarenes are calixarene-like molecules containing a metacyclophane skeleton with at least one bridge larger than methylene [1], which are akin, by their structure if not by their synthesis, to homooxacalixarenes [2]. Up to now, these molecules have been far less investigated than homooxacalixarenes.…”

“…Up to now, these molecules have been far less investigated than homooxacalixarenes. Although the ionophoric properties of some homocalixarene derivatives have been studied in solution [1,3,4], little is known of the structures of their metal ion complexes. Following the work of Harrowfield [5,6], we have been engaged in the past years in a study of the solid-state structure of uranyl complexes of calixarenes, homooxa-and homoazacalixarenes and a wide range of complexes with macrocycles of variable size is now available [7].…”

Calix[3]arene-Analogous Metacyclophanes: Synthesis, Structures and Properties with Infinite Potential

“…The spirodienone route [ 14 ] and Lhtoak’s mercuration [ 15 ] route, however, are notable exceptions for effecting the direct modifications to the basic calix[4]arene skeleton not specifically involving the functionalization of the upper and/or lower rims, or via convergent fragment-based approaches. Since there are many excellent reviews and monographs that have been published on calixarenes, and their more typical analogues, including homocalixarenes [ 16 ], homooxacalixarenes [ 17 , 18 ], azacalixarenes [ 19 ] and hexahomoazacalixarenes [ 20 ], and other types [ 21 , 22 ] the reader is referred to these so will not be further elaborated upon here. Instead, for this review, we have chosen to emphasize the MCP skeleton that has been extensively explored as a versatile and stable platform, or scaffold, for functionalization and study.…”

Homoselenacalix[n]arenes

“…Besides the extensively explored classical carbon-bridged calix[ n ]arenes, several other families of “calixarenoid” macrorings with particular properties have been developed and the chemistry of some of these calixarene-like metacyclophanes has been rejuvenated in recent years. Among those, heteracalixarenes, in which the traditional methylene linkages between the aromatic units are replaced by heteroatoms (e.g., S, NR or O), and homoheteracalixarenes, calixarene analogues in which one or more methylene units are expanded to CH 2 XCH 2 groups (X = O, NR or S), − are particularly attractive since they introduce heteroatoms which might provide additional binding sites.…”

“…The presence of additional methylene units (and possibly heteroatoms) in homocalixarenes results in an enlarged cavity size as well as conformational flexibility, features that might be advantageous for binding guests in an induced-fit fashion. − Within the subgroup of homoheteracalixarenes, the oxygenated analogues have been studied most intensively. , Different combinations and permutations of CH 2 and CH 2 OCH 2 groups have afforded various macrocyclic homooxacalixarene frameworks. Hexahomotrioxacalixarenes, the most available symmetrical homologues within this family, have been applied as efficient synthetic hosts for both metal and organic (quaternary ammonium) ions, and fullerenes, , while an oxovanadium complex has recently been shown to be a superior olefin polymerization catalyst . The synthesis and host−guest properties of homoaza- and homothiacalixarenes have also been explored, although to a lesser extent. , However, to date, there have been no reports of an extension of (homo)heteracalixarene chemistry to the corresponding third or fourth-row “isologues” of the chalcogen series …”