TY - JOUR
T1 - Russian doll assembled superanion capsule-metal ion complexes
T2 - Combinatorial supramolecular chemistry in aqueous media
AU - Hardie, Michaele J.
AU - Raston, Colin L.
PY - 2000/12/1
Y1 - 2000/12/1
N2 - The focus of this perspective is the self assembly in aqueous solutions (pH < 3.5) of the synthons sodium /7-sulfonatocalix[4]arene and 18-crown-6, or related macrocycles, into globular superanions or ionic capsules, for example {Na+⊂(18-crown-6)(OH2) n}C{(p-sulfonatocalix[4]arene(4-))2}7-, n = 0 or 2. These cany crystallise, often selectively, polynuclear hydrolytic metal(in) cations [M2(OH)2(H2O)8]4+, [M3(OH)4(H1O)10]5+, [M1(OH)6(H2O)12]6+, M = Cr or Rh, or [Al13O4(OH)24(H2O) 12]7+, depending on the pH and other synthetic parameters, which are established using a combinatorial approach. These superanions are ambivalent; two calixarenes shroud a crown ether with a central sodium ion bound also by two /raws-water molecules or two oxygen centres of sulfonate groups from each of the calixarenes. Electrostatic repulsion between the negatively charged calixarenes is compensated by the large polynuclear cations interacting with the negatively charged hydrophilic equatorial region of the capsule, and some protonation of the sulfonate groups. Similarly, protonated cyclam forms a capsule with two calixarenes and crystallises [Cr2(OH)2(H2O)8]4+. Lanthanide(Hi) ions form a range of complexes at specific pH in the presence of the calixarene and crown ether, including complexes containing the capsule [{18-crown-6}C {(M(H2O)73+),.33(p-sulfonatocalix[4]arene(4-))}2], for the smaller lanthanides, or the ferris wheel type structure [{La3+C(18-crown-6)(OH2)j}n{(p-sulfonatocalix[4]arene-(4-) + 2H+)}]+, for the larger lanthanide. Only some of the continuous structures have an up-down bilayer arrangement of calixarenes.
AB - The focus of this perspective is the self assembly in aqueous solutions (pH < 3.5) of the synthons sodium /7-sulfonatocalix[4]arene and 18-crown-6, or related macrocycles, into globular superanions or ionic capsules, for example {Na+⊂(18-crown-6)(OH2) n}C{(p-sulfonatocalix[4]arene(4-))2}7-, n = 0 or 2. These cany crystallise, often selectively, polynuclear hydrolytic metal(in) cations [M2(OH)2(H2O)8]4+, [M3(OH)4(H1O)10]5+, [M1(OH)6(H2O)12]6+, M = Cr or Rh, or [Al13O4(OH)24(H2O) 12]7+, depending on the pH and other synthetic parameters, which are established using a combinatorial approach. These superanions are ambivalent; two calixarenes shroud a crown ether with a central sodium ion bound also by two /raws-water molecules or two oxygen centres of sulfonate groups from each of the calixarenes. Electrostatic repulsion between the negatively charged calixarenes is compensated by the large polynuclear cations interacting with the negatively charged hydrophilic equatorial region of the capsule, and some protonation of the sulfonate groups. Similarly, protonated cyclam forms a capsule with two calixarenes and crystallises [Cr2(OH)2(H2O)8]4+. Lanthanide(Hi) ions form a range of complexes at specific pH in the presence of the calixarene and crown ether, including complexes containing the capsule [{18-crown-6}C {(M(H2O)73+),.33(p-sulfonatocalix[4]arene(4-))}2], for the smaller lanthanides, or the ferris wheel type structure [{La3+C(18-crown-6)(OH2)j}n{(p-sulfonatocalix[4]arene-(4-) + 2H+)}]+, for the larger lanthanide. Only some of the continuous structures have an up-down bilayer arrangement of calixarenes.
UR - http://www.scopus.com/inward/record.url?scp=33746564187&partnerID=8YFLogxK
U2 - 10.1039/b002047h
DO - 10.1039/b002047h
M3 - Article
AN - SCOPUS:33746564187
SN - 1470-479X
SP - 2483
EP - 2492
JO - Journal of the Chemical Society. Dalton Transactions
JF - Journal of the Chemical Society. Dalton Transactions
IS - 15
ER -