They design a new hybrid material fluorescent that changes of colour with the steering of the light
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The hybrid materials, with an organic component and another inorganic, look for to combine the best attributes of both in an alone system. Laboratories of all the world work in the development of new hybrid materials for technological applications, especially, in the nanotechnologies, and use already in light materials for trucks, in sportive equipment, in materials biomiméticos, like prosthesis, etcetera.
The hybrid material that looked for the group of investigation of the Department of Physical Chemicals had to fulfil a series of requirements very specific. They needed that the inorganic material host went a crystalline structure with nanocanales parallel, so that the molecules of the organic material guest, a colorante, could range ; they needed that the size of the pores of the host was inferior to 1nm (the millionth part of 1 millimetre) so that the colorante adjusted closely; they needed, finally, no one, but two colorantes, of size and similar form, but with complementary optical properties that answered of different form when being stimulated by the light.
The main challenge was, therefore, attain that adjust perfect between the nanoestructura inorganic and the molecules of colorante. They achieved it using like host material an aluminofosfato (AIPO-11), that has a size of ideal pore to lodge colorantes with a structure of three rings bencénicos merged, as they are the elected: the pironingingina, of green fluorescence, and the acridina, of blue fluorescence. “The colorantes go in orderly, range along the nanocanales, and his fluorescent properties improve inside them”, explains Virginia Martínez, researcher Ramón and Cajal of the group of Molecular Spectroscopy. The improvement has to no only to that restricts the molecular flexibility of the colorante, but also to that this remains included of form monomérica, that is to say, goes in in the channel in separate units and thanks to this are very luminescent, as the fluorescence loses when they add .
To achieve that adjust perfect, played a fundamental paper the procedure of synthesis. In the hybrid materials fotoactivos, usually, the organic part enters in the inorganic from the phase gas or liquid, by means of diffusion, but with this method does not achieve the level of occlusion that this investigation needed. So they opted for entering the colorante in the gel with which sintetiza the inorganic material, so that to measure that the glass grew went incorporating the cromóforo organic.
At the beginning entered an alone colorante, the pironingingina, and obtained a highly luminescent material. In fact, using microscopy confocal of fluorescence, registered a practically total alignment of the molecules of colorante along the channel (reason dicroica of 40), an alignment that had not reported previously.
To continuation, entered at the same time the pironingingina and the acridina in the process of synthesis, and obtained some rectangular glasses of 30x20 micras that changed llamativamente of colour according to the polarisation of the light with which lit : if it was polarised along the channel saw green; if it was perpendicular, showed blue colour. This behaviour indicated that it produced a transfer of power between the colorantes.
“The sintonización of the colour is, besides, an instantaneous and efficient process, entirely reversible and reproducible, with high resistance to the fatigue”, signals Iñigo López Arbeloa. From here that the possible applications of this type of hybrid materials fotoactivos are multiple: they can be used like antennas in photovoltaic cells, for storage of information, in photonic cables, in systems laser… In fact, the new hybrid material supposes an advance in the development of lasers sintonizables in solid state, of big interest biomédico, since they are easier to use and less contaminantes that the liquids used at present.
