Single-wall carbon nanotube porphyrin nanoconjugates

We describe the synthesis, microscopic and spectroscopic characterization of a novel donor-acceptor prototype, namely, a single wall carbon nanotube (SWNT) nanoconjugate bearing a covalently linked free base porphyrin (H2P). In the characterized SWNT-H2P nanoconjugate the electronic features of SWNT are largely retained, when compared to pristine SWNT. In fact, carefully controlled reaction conditions lead to a low degree of SWNT functionalization, as evidenced by the preservation of the SWNT van Hove singularities. As a consequence, the overall SWNT loading with H2P is so low that in the ground state, the H2P features are barely seen, which is different from the excited state, where features of H2P are clearly discernable. For example, fluorescence and transient absorption characteristics corroborate, unequivocally, the formation of the H2P singlet excited state, which is, however, impacted by the presence of SWNT. Copyright (C) 2007 Society of Porphyrins & Phthalocyanines.