Fused Porphyrin–Single-Walled Carbon Nanotube Hybrids: Efficient Formation and Photophysical Characterization

Abstract

A systematic study of the interaction between π-extended porphyrins and single-walled carbon nanotubes (SWNTs) is reported here. Zinc porphyrins with 1-pyrenyl groups in the 5,15-meso positions, 1, as well as compounds where one or both of the pyrene groups have been fused at the meso and β positions of the porphyrin core, 2 and 3, respectively, have been examined. The strongest binding to SWNTs is observed for porphyrin 3, leading to debundling of the nanotubes and formation of stable suspensions of 3-SWNT hybrids in a range of common organic solvents. Absorption spectra of 3-SWNT suspensions are broad and continuous (λ=400-1400 nm), and the Q-band of 3 displays a significant bathochromic shift of 33 nm. The surface coverage of the SWNTs in the nanohybrids was estimated by spectroscopic and analytical methods and found to reach 64% for (7,6) nanotubes. The size and shape of π-conjugated porphyrins were found to be important factors in determining the strength of the π-π interactions, as the linear anti-3 isomer displays more than 90% binding selectivity compared to the bent syn-3 isomer. Steady-state photoluminescence measurements show quenching of porphyrin emission from the nanohybrids. Femtosecond transient absorption spectroscopy reveals that this quenching results from ultrafast electron transfer from the photoexcited porphyrin to the SWNT (1/kCT=260 fs) followed by rapid charge recombination on a picosecond time scale. Overall, our data demonstrate that direct π-π interaction between fused porphyrins and SWNTs leads to electronically coupled stable nanohybrids.

Coordination chemistry on carbon surfaces

“…Some reports also mention the use of pyrene moieties to immobilize on SWCNTs or graphene surfaces metallomacrocycles like porphyrines or phthalocyanines (see Table 11) [163,[189][190][191][192][193][194][195][196], mainly for the preparation of donor-acceptor hybrid systems for photoinduced electron transfer. Generally, 1D or 2D sp 2 carbon nanomaterials are employed as electron acceptors in association with excited state electron donors.…”

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.…”

A facile strategy to generate polymeric nanoparticles for synergistic chemo-photodynamic therapy

“…The π-π stacking interaction was helpful for drug loading, 6 which was 30 used to absorb massive anticancer drugs on carbon nanotube and graphene. 6,7 π-π stacking interaction was reported in low molecular weight hydrogels (LMWH) with exciting drug loading content 8 and anticancer efficacy. Polymeric nanoparticles are important carriers, different from carbon nanomaterials and 35 LMWH, 8,9 the encapsulation pattern in drug loading 10 led to poor loading content, although crosslinking and conjugation were attempted to improve drug loading content in polymeric nanoparticles, 11 rare optimistic results were received.…”