An interesting and well known chemical reaction (tautomerism) in free-base porphyrins (namely H2TPP) has been considered promising for application in organic electronics. Recently, we have proposed an original strategy to obtain a pure 2D layer of H2TPP molecules, where tautomers are aligned along the same direction, inducing anisotropy in the porphyrin optical transitions. This opens the route to an organic optical device if the tautomer signal can be inhibited and restored in a controlled mode. Here, we demonstrate that, conversely to H2TPP film, the di-acid H4TPP sample, easily reachable from free-base porphyrins, shows almost isotropic transitions. The change of the optical spectral intensities between H2TPP and H4TPP samples, as detected by reflectance anisotropy spectroscopy (RAS), is interpreted in terms of two distinct logic states. Furthermore, RAS spectra acquired both on the H2TPP and the H4TPP samples are compared with the optical spectra of ultra-thin films of ZnTPP, the latter being a genuine isotropic porphyrin.
Bussetti, G., Campione, M., Sassella, A., Duò, L. (2015). Optical and morphological properties of ultra-thin H2TPP, H4TPP and ZnTPP films. PHYSICA STATUS SOLIDI B-BASIC RESEARCH, 252(1), 100-104 [10.1002/pssb.201350260].
Optical and morphological properties of ultra-thin H2TPP, H4TPP and ZnTPP films
CAMPIONE, MARCELLO;SASSELLA, ADELE;
2015
Abstract
An interesting and well known chemical reaction (tautomerism) in free-base porphyrins (namely H2TPP) has been considered promising for application in organic electronics. Recently, we have proposed an original strategy to obtain a pure 2D layer of H2TPP molecules, where tautomers are aligned along the same direction, inducing anisotropy in the porphyrin optical transitions. This opens the route to an organic optical device if the tautomer signal can be inhibited and restored in a controlled mode. Here, we demonstrate that, conversely to H2TPP film, the di-acid H4TPP sample, easily reachable from free-base porphyrins, shows almost isotropic transitions. The change of the optical spectral intensities between H2TPP and H4TPP samples, as detected by reflectance anisotropy spectroscopy (RAS), is interpreted in terms of two distinct logic states. Furthermore, RAS spectra acquired both on the H2TPP and the H4TPP samples are compared with the optical spectra of ultra-thin films of ZnTPP, the latter being a genuine isotropic porphyrin.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.