RESUMO
Metal-organic frameworks (MOFs) capable of mobility and manipulation are attractive materials for potential applications in targeted drug delivery, catalysis, and small-scale machines. One way of rendering MOFs navigable is incorporating magnetically responsive nanostructures, which usually involve at least two preparation steps: the growth of the magnetic nanomaterial and its incorporation during the synthesis of the MOF crystals. Now, by using optimal combinations of salts and ligands, zeolitic imidazolate framework composite structures with ferrimagnetic behavior can be readily obtained via a one-step synthetic procedure, that is, without the incorporation of extrinsic magnetic components. The ferrimagnetism of the composite originates from binary oxides of iron and transition metals such as cobalt. This approach exhibits similarities to the natural mineralization of iron oxide species, as is observed in ores and in biomineralization.
RESUMO
We present the site-selective, parallel and reproducible formation of conductive gold and tetrathiafulvalene-gold (TTF-Au) hybrid micro- and nanowires from their respective ion salt and cation-radical solutions. While the formation of micro- and nanowires by means of dielectrophoresis with directly coupled electrodes has been thoroughly investigated in recent studies, we present here the first relevant example of metal and hybrid wire assembly obtained by floating potential dielectrophoresis. In this configuration, the assembly of micro- and nanowires is achieved by capacitively coupling a large electrode (bias electrode) to a conductive substrate (p-doped Si) separated by an insulating oxide layer. In contrast to former studies, this allows parallel production of micro- and nanowires with only one pair of electrodes connected to a sine wave generator. We further demonstrate that these structures are suitable probes for localized surface enhanced Raman spectroscopy (SERS).