In this paper we report on the successful patterning of crystalline aggregates of the neutral spin-transition complex cis-bis(thiocyanato) bis(1,10-phenanthroline)iron(II), with controlled size at the frontier of micrometric-(thus optically accessible) and nanometric-scaled structures. The selected compound, one of the most thoroughly investigated spin transition ones, exhibits a transition from low to high spin at 176 K and it can be considered a representative for this class of switchable metal complexes. Unconventional and soft lithography techniques have been used to fabricate reliably nanopatterns of the compound. Microinject molding in capillaries to fabricate micrometric stripes and lithographically controlled wetting enable to pattern sub-micrometric and nanostructures. Noticeably both methods exploit the self-organisation properties of molecules at the later stages of shrinking. The ST compound could be lithographically processed into crystalline micro- and nanostripes as well as into logic patterns on a technologically relevant surface. The obtained patterns were characterized by atomic force microscopy (AFM), polarized optical microscopy, grazing incidence X-ray diffraction (GIXD), and Raman spectroscopy.The appearance of crystallinity in well-oriented nanostructures is a breakthrough, since molecular ST properties critically depend on the uniformity of the local environment around the ST switching units. In this respect, our work represents an important advance in view of the application of ST compounds in molecular devices. In forthcoming work, the resolution of the nanopatterning process can still be scaled down to smaller length scales. In addition, further technological developments such as encapsulation of ST compounds (to overcome the stability problem), the realization of processable room temperature ST, or the introduction of new triggers (e.g. electrical fields) for device integration is under progress. This ongoing work will lead to the development of new generation storage media based on a variety of molecular responses, for instance spin flip, conformational, optical anisotropy changes and changes of the dielectric constant.
Micro-and Nanopatterning of a Spin Transition Compound into Logical Structures
Cavallini M;Bergenti I;Milita S;Ruani G;
2008
Abstract
In this paper we report on the successful patterning of crystalline aggregates of the neutral spin-transition complex cis-bis(thiocyanato) bis(1,10-phenanthroline)iron(II), with controlled size at the frontier of micrometric-(thus optically accessible) and nanometric-scaled structures. The selected compound, one of the most thoroughly investigated spin transition ones, exhibits a transition from low to high spin at 176 K and it can be considered a representative for this class of switchable metal complexes. Unconventional and soft lithography techniques have been used to fabricate reliably nanopatterns of the compound. Microinject molding in capillaries to fabricate micrometric stripes and lithographically controlled wetting enable to pattern sub-micrometric and nanostructures. Noticeably both methods exploit the self-organisation properties of molecules at the later stages of shrinking. The ST compound could be lithographically processed into crystalline micro- and nanostripes as well as into logic patterns on a technologically relevant surface. The obtained patterns were characterized by atomic force microscopy (AFM), polarized optical microscopy, grazing incidence X-ray diffraction (GIXD), and Raman spectroscopy.The appearance of crystallinity in well-oriented nanostructures is a breakthrough, since molecular ST properties critically depend on the uniformity of the local environment around the ST switching units. In this respect, our work represents an important advance in view of the application of ST compounds in molecular devices. In forthcoming work, the resolution of the nanopatterning process can still be scaled down to smaller length scales. In addition, further technological developments such as encapsulation of ST compounds (to overcome the stability problem), the realization of processable room temperature ST, or the introduction of new triggers (e.g. electrical fields) for device integration is under progress. This ongoing work will lead to the development of new generation storage media based on a variety of molecular responses, for instance spin flip, conformational, optical anisotropy changes and changes of the dielectric constant.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
