Rational Design of Cesium‐Selective Ionophores: Dihydrocalix[4]arene Crown‐6 Ethers

Abstract

Molecular mechanics calculations performed on calix[4]arene crown‐6 ethers predict that the 1,3‐dihydro derivatives will exhibit greater complementarity for potassium and cesium ions than the parent 1,3‐bis(alkyloxy) calixcrowns. The X‐ray crystal structures of 1,3‐alt‐bis(octyloxy)calix[4]arene benzocrown‐6 ether, dihydrocalix[4]arene benzocrown‐6 ether, and the cesium nitrate complex of dihydrocalix[4]arene benzocrown‐6 ether were determined. The structure of the cesium complex corresponds closely to the structure predicted by molecular mechanics. The dihydrocalix[4]arene crown‐6 ethers exhibit enhanced cesium selectivity in the extraction of alkali‐metal salts. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

First Synthesis of 1,3-Alternate 25,27-Dialkyloxy-5,17-diarylcalix[4]arenes-crown-6 as New Cesium Selective Extractants by Suzuki Cross-coupling Reaction

“…The remaining Cs -O crown bond lengths in the coordination sphere are spread over a wide range [3.152(9) -3.885(7) Å for molecule A and 3.089(8) -3.506(7) Å for molecule B]. Data appear consistent with the O phenyl -O phenyl distances for previously reported Cs·calix [4]arene-crown-6 structures, which range from 4.7 to 4.9 Å , and with typical Cs -O phenyl distances observed between 3.2 and 3.3 Å [7,8,32,34,35]. In both A and B molecules, the crown-6 moiety is bent to allow the participation of the picrate ion in the coordination sphere of the cation via its phenoxy oxygen [d(Cs -O1Pic) ¼ 2.958(14) and 3.111(8) Å , respectively].…”

“…4.790(8) and 4.491(8) Å , respectively, and the distances between the two phenyl rings bearing the alkyloxy moieties (C16 -C42) were 6.619(9) and 7.425(9) Å , respectively. Similar O phenyl -O phenyl distances in the previously described 1,3-alternate dioctyloxycalix [4]arene benzocrown-6 [32] were found at 4.543 and 4.61 Å , while the homologous C -C distances range from 7.05 to 7.07 Å .…”

“…The bonding interactions between a cation and an arene can be characterized by two geometric parameters: the distance d, between the cation and the centroid of the arene ring, and the tilt angle C defined as the angle between the cation -centroid vector and the normal to the arene plane. The stability of the complexes is related to the minimal values [32]. The calculated distances d are of 3.66 and 3.91 Å for molecule A, and 3.79 and 4.01 Å for molecule B, respectively (Table IV).…”

“…3 and 4). The structure of 1a can be compared to that of 1,3-alternate dioctyloxycalix [4]arene benzocrown-6 [32], the only previously published structure of an uncomplexed 1,3-alternate dialkyloxycalix [4]arene crown-6 ether (Table II). Two molecules (designed as A and B) were found in the asymmetric unit, each with a distinct crown conformation.…”

Thermodynamical Criteria of the Higher Selectivity of Zirconium Oxycations over Hafnium Oxycations towards Organophosphorus Ligands: Density Functional Theoretical Investigation

“…[7,8] Design concepts based on quantum mechanics (QM) were applied to a bidentate ligand to obtain a remarkable enhancement in Eu 3+ ion binding affinity [9] and calix-crown-based Csselective ionophores. [10] Here, our system of interest is very important and useful for nuclear materials such as Hf and Zr ions. Hf has a filled 4f orbital, whereas Zr has no 4f electrons.…”