Interaction of Porphyrins with Carbon Nanotube

Porphyrins are the light-absorbing chromophores that play a central role in photosynthesis. They show absorption in the 400–450 nm region of Soret band and in the 500–700 nm region of Q-bands and are particularly interesting for their long-lived intermediate electronic state that is accessed upon their irradiation by visible light. A variety of spectroscopic studies performed in solution indicate1,2 that a photoinduced electron transfer (PET) occurs from the porphyrin to the carbon-based species. Cu(II) and Zn(II) complexes of Coproporphyrin-I (2,7,12,17-tetrapropionic acid of 3,8,13,18- tetramethyl-21H,23H porphyrin or CPI), has been synthesized in our laboratory and tested as sensitizers in DSSC 3. In this study the reactions of CPI, CPIZn and CPICu with CNT have been monitored, with Uv-Vis Spectroscopy, and kinetics and thermodynamic data of CNT-(CPI-dyes) it has been obtained. The obtained “compounds” has been characterized after absorption on conventional nanostructured semiconducting TiO2 layer with scanning electron microscopy (SEM). The CNT-(CPI-dyes) concentrations and adsorption times affected the adsorption on TiO2 surfaces and the equilibrium and kinetic data obtained have permit to establish the best experimental conditions for the adsorption of these CNT-(CPI-dyes) and have demonstrated that these, according to the Langmuir model and with pseudo first-order kinetics, are adsorbed effectively in the support of TiO2 monolayer. The obtained CNT-(CPI-dyes) will be used as sensitizers in order to explore their potentiality in the DSSC applications.