ISSN:
0947-6539
Keywords:
crown ethers
;
layered materials
;
molecular recognition
;
zirconium phosphate
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The topotactic exchange reactions of γ-zirconium phosphate and γ-zirconium phosphate/methylphosphonate with phosphonic acids derived from azacrown ethers of different sizes was examined. Prior intercalation of hexylamine was necessary in most cases to attain the maximum exchange level predicted by molecular modeling. Materials with imbricated or nonimbricated layers were obtained depending on crown size and exchange level. Exchange of methylphosphonates in γ-zirconium phosphate/methylphosphonate was only observed when hexylamine had previously been intercalated. The exchange with the bisphosphonic acid derived from 1,10-diaza[18]-crown-6 gave a material with an interlayer distance compatible with pillaring of the γ-phase. The materials obtained from the exchange reactions of γ-zirconium phosphate with phosphonic acids derived from [12]crown-4 and [18]crown-6 showed thermodynamic selectivities towards Na+ and K+, respectively, that were much higher than those observed for the simple crowns in solution. This observation suggests that the inorganic molecular framework enhances molecular recognition by minimization of solvation effects.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/chem.19960021217
