Synthesis and ion selectivity of conformers of tetraalkyl esters derived from 9,16,25,32-tetrahydroxy[3.1.3.1]metacyclophane

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

“…The two complexes ½HNEt 3 2 ½UO 2 ðL 1 Þ·CHCl 3 · CH 3 CN 1 and ½HNEt 3 2 ½UO 2 ðL 2 Þ·2:67H 2 O 2 present common features in what concerns the complex core itself, and these features are close to those observed in the uranyl complexes of tetrahomodioxacalix [4]arene, denoted L 3 H 4 in the following, whatever its parasubstituents [10,11]. The repeat unit comprises one complex molecule in compound 1 (Fig.…”

“…The overall packing is thus constituted of two sub-networks with molecules at approximate right angles, the interactions between these two subunits being seemingly of the van der Waals type. It is interesting to note that a columnar arrangement with an alternate stacking of anionic complexes and groups of two triethylammonium counter-ions has previously been found in the uranyl ion complex of p-phenyltetrahomodioxacalix [4]arene [11]. The shortest distances between the counter-ions and the aromatic rings in the columns of 2, which involve two a-carbons of the former, are 3.71 and 3.73 Å , the corresponding distances with the centroids being 3.66 and 3.53 Å .…”

“…We have given several examples of such architectures built from uranyl ion complexes of p-R-hexahomotrioxacalix [3]arenes [20] and p-Rtetrahomodioxacalix [4]arenes [11]. The comparison of complexes 1 and 2 is interesting in this respect.…”

“…We report herein the results obtained with 9,16,25,32-tetrahydroxy[3.1.3.1]metacyclophane, bearing either tert-butyl (L 1 H 4 ) or H (L 2 H 4 ) in the para position (Scheme 1). This ligand, which is a homocalix [4]arene with alternating methylene and 1,3-propylene bridges, is closely related to tetrahomodioxacalix [4]arene (or [3.1.3.1] homooxacalixarene), with alternating methylene and 2-oxa-1,3-propylene bridges [2]. The latter, with methyl, tert-butyl or phenyl para-substituents, has been structurally characterized either free or as a solvate [9,10], or in its uranyl-complexed form [10,11].…”

“…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].…”