Noncovalent porphyrin-functionalized single-walled carbon nanotubes: solubilization and spectral behaviors

Abstract

We describe the solubilization/dispersion of as-produced and purified single-walled carbon nanotubes (raw-SWNTs and p-SWNTs) with protoporphyrin IX derivatives and tetraphenylporphyrin iron(III) chloride, the spectral behavior of the octaalkylporphyrins-solubilized shortened-SWNTs (s-SWNTs), and the electrochemistry of a p-SWNTs/FePP cast film on a glassy carbon electrode. Transmission electron and atomic force microscopies, as well as UV-visible-near IR spectroscopy, revealed that the protoporphyrin IX derivatives individually dissolved the p-SWNTs in polar solvents under mild conditions of sonication using a bath-type sonicator, followed by centrifugation at 1000 g. The raw-SWNTs were more easily dissolved than the p-SWNTs with protoporphyrin IX zinc(II) ( ZnPP ), whereas the amount of the solubilized/dispersed p-SWNTs did not depend on the concentration of the solubilizer and sonication time. The absorption and fluorescence spectral measurements of the octaalkylporphyrins in dimethylformamide containing 1 vol% tetrahydrofuran with various amounts of the s-SWNTs showed that the absorption maxima of the octaalkylporphyrins decreased with an increase in the concentration of the s-SWNTs without wavelength shift and the fluorescence of the porphyrins was quenched by the addition of the s-SWNTs. These spectral behaviors are direct evidence for the interaction between the nanotube sidewall and the porphyrins in the solutions. The cyclic voltammograms of the p-SWNTs/hemin ( FePP ) and free hemin ( FePP ) suggest that the nanotubes act as a conduction passage for electrons between hemin ( FePP ) and the glassy carbon electrode.

The effect of ascorbic acid on the photophysical properties and photodynamic therapy activities of zinc phthalocyanine-single walled carbon nanotube conjugate on MCF-7 cancer cells

“…On adsorption of 2 or 1 onto SWCNTs to form 3 or 4, there was no change in the Q-band maxima of the Pc, however, an enhancement in the B-band intensity due to absorption of SWCNTs was observed. Reports have shown that when Pcs or porphyrins are adsorbed onto carbon nanotubes (CNTs), there is no shift in the absorption bands of the former [46,47]. Similar lack of spectral change has been reported on adsorbing porphyrins onto SWCNTs via p-p interactions [46].…”

Photophysical properties of zinc phthalocyanine–uridine single walled carbon nanotube – conjugates

“…G ⁄ is the non-dispersive phonon mode, G is the tangential vibrational mode (sp 2 ) and D is the breathing mode; disorder band (sp 3 ). CNTs, there is no shift in the absorption bands of the former [33,34], only broadening of the peaks is observed. Broadening of the spectra is observed in this work on adsorption of complex 4…”

Methodology for Homogeneous Dispersion of Single-walled Carbon Nanotubes by Physical Modification

“…We tested a series of porphyrin derivatives and revealed that a wide range of porphyrin derivatives including 21 and 22 (Table III) can also act as effective dispersants for SWNTs. 104 The finding lead the theoretical as well as experimental attempts to understand the interaction between porphyrin and CNTs. [105][106][107] The combination of porphyrin and CNTs has attracted extensive interest due to their unique photophysical, 81,108,109 electrochemical, [110][111][112] electronic, 108,[113][114][115] and optical 116,117 properties.…”