SENSITIVITY AMPLIFICATION IN SELF-ASSEMBLED TUBULAR STRUCTURES OF PORPHYRINS

Nanostructured molecular assembly may provide additional peculiar properties not found in other arrangements of the same basic constituents. Among the three-dimensional structures, nanotubes are particularly appealing for chemical sensor applications at least for the expected surface to volume ratio increase. In this paper, the sensing properties of self-assembled nanotubes of oppositely charged porphyrins are investigated for the first time. The interaction with guest molecules gives rise to changes in the UV-Vis spectrum of nanotubes both in liquid and in solid-state. The optical properties were adequately measured by a simple set-up based on a computer screen as light source and a digital camera as detector. Porphyrins nanotubular structures exhibited an enhanced sensitivity to various compounds with respect to those shown by the single porphyrins. The reason of the increased sensitivity may be found in an additional sensing mechanisms related to the modulation of the strenght of the forces that keep the nanotube together.