Premium
Crown‐Shaped Tungstogermanates as Solvent‐Controlled Dual Systems in the Formation of Vesicle‐Like Assemblies
Author(s) -
Artetxe Beñat,
Reinoso Santiago,
San Felices Leire,
GutiérrezZorrilla Juan M.,
García José A.,
Haso Fadi,
Liu Tianbo,
Vicent Cristian
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201500373
Subject(s) - crystallography , chemistry , supramolecular chemistry , monomer , vesicle , acetone , solvent , lanthanide , ion , stereochemistry , crystal structure , organic chemistry , biochemistry , membrane , polymer
Reaction of early lanthanides, GeO 2 , and Na 2 WO 4 in a NaOAc buffer results in large crown‐shaped polyoxometalates based on [Ln 2 GeW 10 O 38 ] 6− subunits. By using Ni 2+ as a crystallizing agent, [Na⊂Ln 12 Ge 6 W 60 O 228 (H 2 O) 24 ] 35− ( Na⊂Ln 12 ) hexamers formed by alternating β(1,5)/β(1,8) subunits were obtained for Ln=Pr, Nd. The addition of K + led to a similar anion for Ln=Sm, namely, [K⊂Sm 12 Ge 6 W 60 O 228 (H 2 O) 22 ] 35− ( K⊂Sm 12 ) and [K⊂K 7 Ln 24 Ge 12 W 120 O 444 (OH) 12 (H 2 O) 64 ] 52− ( K⊂Ln 24 ) dodecamers that consist of a central core identical to K⊂Sm 12 decorated with six external γ(3,4) subunits for Ln=Pr, Nd. These anions dissociate in water into hexameric cores and monomeric entities, as shown by ESI mass spectrometry. The former self‐assemble into spherical, hollow, and single‐layered blackberry‐type structures with radii of approximately 75 nm, as monitored by laser light scattering (LLS) and TEM techniques. Analogous studies performed for K⊂Nd 24 in water/acetone mixtures show that the dodecamers remain stable and form in turn their own type of blackberries with sizes that increase from approximately 20 to 50 nm with increasing acetone content. This control over both the composition and size of the vesicle‐like assemblies is achieved for the first time by modifying the architecture of the species that undergoes supramolecular association through the solvent polarity.