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Nanometer‐Sized Molybdenum–Iron Oxide Capsule‐Surface Modifications: External and Internal
Author(s) -
Müller Achim,
Bögge Hartmut,
Sousa Filipa L.,
Schmidtmann Marc,
Kurth Dirk G.,
Volkmer Dirk,
van Slageren Joris,
Dressel Martin,
Kistler Melissa L.,
Liu Tianbo
Publication year - 2007
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.200600567
Subject(s) - molybdenum , materials science , molybdate , nanochemistry , nanomaterials , capsule , metal , nanoparticle , lanthanide , metal ions in aqueous solution , crystallography , nanotechnology , chemical engineering , ion , chemistry , organic chemistry , botany , engineering , metallurgy , biology
The cluster {(Mo)Mo 5 } 12 Fe III 30 1 a present in compound 1 (cluster diameter ≈2.3 nm), which belongs to the family of nanoscale spherical porous {(Mo)Mo 5 } 12 {Linker} 30 capsules that allow a new type of nanochemistry inside their cavities as well as unprecedented aggregation processes under gaseous, solution, and solid‐state conditions, is the starting material for the present investigation. In solution it reacts with LnCl 3 ⋅nH 2 O (Ln=Ce, Pr) thereby replacing six Fe III ions with Ln III ions to form compounds 2 (Ce) and 3 (Pr). During metal‐cation exchange, some of the pentagonal {(Mo)Mo 5 O 21 (H 2 O) 6 } 6− units, which are connected to the Fe III centers in 1 a , decompose, thus leading to a temporary capsule opening and uptake of the formed smaller molybdate units into the capsule cavities. In 2 and 3 , the pentagonal units are connected via 24 Fe III and six Ln III ‐type linkers/spacers representing together the capsule skeletons, which are structurally well‐defined in contrast to the capsule contents. The new capsules self‐associate into single‐layer blackberry‐type structures, thus extending the variety of these types of assemblies; the assembly process, that is, the size of the final species, can be controlled by the pH, which allows the generation of differently sized nanoparticles. Magnetic properties of the two new nanomaterials 2 and 3 are also determined.