Controlled Uptake and Release of Metal Cations by Vanadium Oxide Nanotubes

✍ Scribed by J. Matias Reinoso; Hans-Joachim Muhr; Frank Krumeich; Fabian Bieri; Reinhard Nesper

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: German
• Weight: 377 KB
• Volume: 83
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/1522-2675(20000809)83:8<1724::aid-hlca1724>3.0.co;2-g

✦ Synopsis

Dedicated to Prof. Albert Eschenmoser on the occasion of his 75th birthday

Vanadium oxide nanotubes (C n -VO x -NTs) contain a-monoamines (C n H 2n1 NH 2 with 4 n 22) as templates intercalated between crystalline VO x layers comprising multilayer tube walls. The present study reveals that a large proportion of the amines can easily be exchanged by metal cations. The tubular morphology is not affected by this reaction, but the distance between the VO x layers, i.e., 2.8 nm in C 12 -VO x NTs, decreases in the reaction product to 0.9 ± 1.2 nm, depending on the metal salt actually applied. Alkali (Na , K ), alkalineearth (Mg 2 , Ca 2 , Sr 2 ), and transition-metal salts (Fe 2 , Co 2 , Ni 2 , Cu 2 ) have successfully been intercalated. This reaction is partly reversible since intercalated sodium cations can be resubstituted by dodecylamine. This exchange produces again C 12 -VO x -NTs with the original inter-layer spacing. However, this release is successful only when sodium is complexed by a crown ether. Under these reaction conditions, even a cyclic uptake and release of Na and amine, respectively, accompanied by a corresponding shrinkage and widening of the interlayer distance, is observed while the tubular structure is widely preserved. Furthermore, a distinct selectivity of the metal-cation exchange has been observed.