Efficient photosensitized energy transfer and near-IR fluorescence from porphyrin–SWNT complexes

Abstract

Energy transfer from photoexcited porphyrin molecules to single-walled carbon nanotubes (SWNTs) has been experimentally detected for samples in aqueous Triton X-100 micellar suspensions. Addition of SWNTs to micelle-suspended porphyrin results in strong quenching of porphyrin fluorescence. Measurements of concentration-dependent quenching and spectra suggest that this process arises from formation of ground state non-covalent complexes between porphyrins and SWNTs. Optical excitation of the porphyrin generates characteristic near-IR emission from the SWNTs, indicating efficient energy transfer within the complexes. This energy transfer is deduced to occur through a Dexter-type electron exchange mechanism. Complexation of SWNTs with organic photosensitizers provides a novel way of uniformly exciting a wide range of nanotube structural species in polydisperse samples using only a single excitation wavelength.

Quantum efficiency of energy transfer in noncovalent carbon nanotube/porphyrin compounds

“…The spot at (x=1.240 eV, y=2.805 eV) corresponds to absorption on the Soret-band and emission by nanotubes. This brings evidence for excitation energy transfer from the porphyrin to the nanotube: when photons are absorbed by the porphyrin molecules, the luminescence of the nanotube is enhanced [6][7][8]. We assign the PLE feature at an excitation energy of 2.357 eV to EET upon absorption on the porphyrin higher Q band, red shifted of about 50 meV in comparison with free porphyrins.…”

“…Therefore usual covalent chemistry, which leads to deep defects formation due to local destruction of the π-electronic system, should be avoided. In contrast, the use of non-covalent chemistry (such as π-stacking interaction) has proven to be compatible with high quality transport and optical properties of the nanotubes [6][7][8]. On the other hand it usually leads to poorly stable compounds [6][7][8].…”

“…In contrast, the use of non-covalent chemistry (such as π-stacking interaction) has proven to be compatible with high quality transport and optical properties of the nanotubes [6][7][8]. On the other hand it usually leads to poorly stable compounds [6][7][8]. Recently, an original method based on micelle encapsulation of the nanotube/molecule compound has been demonstrated that allows both stability and minimal perturbation to the nanotube properties [8].…”

“…In this Letter, we study SWNT/porphyrin compounds which are known for showing EET [6][7][8] and we perform a quantitative investigation of the strength of this coupling in the case of (6,5) nanotubes by measuring the quantum yield and the dynamics of the energy transfer. Purified CoMoCAT nanotubes (SouthWest Nanotechnologies, SG65) containing mainly the (6,5) chirality were functionalized with base-free tetraphenyl porphyrin (TPP) by means of the micelle swelling method (see [8] for details).…”

Single- and double-wall carbon nanotubes fully covered with tetraphenylporphyrins: Stability and optoelectronic properties from ab initio calculations

“…This supramolecular assembly has been explored recently as light-harvesting donor/acceptor complexes [1][2][3][4][5][6][7][8][9][10] , as well as for the electrocatalysis of the oxygen reduction reaction [11][12][13][14] . Some schemes proposed for the such a functionalization include the CNT encapsulation in micelles of surfactant 15 or in polymers.…”