TY - JOUR
T1 - Synthesis, characterization, redox properties, and photodynamics of donor-acceptor nanohybrids composed of size-controlled cup-shaped nanocarbons and porphyrins
AU - Ohtani, Masataka
AU - Saito, Kenji
AU - Fukuzumi, Shunichi
PY - 2009/9/14
Y1 - 2009/9/14
N2 - Cup-shaped nanocarbons (CNC) generated by the electron-transfer reduction of cup-stacked carbon nanotubes have been functionalized with porphyrins (H 2P) as light-capturing chromophores. The resulting donor-acceptor nanohybrid has been characterized by thermogravimetric analysis (TGA), Raman and IR spectroscopy, transmission electron microscopy, elemental analysis, and UV/Vis spectroscopy. The weight of the porphyrins attached to the cup-shaped nanocarbons was determined as 20% by TGA and elemental analysis. The UV/Vis absorption spectrum of CNC-(H2P)n in DMF agrees well with that obtained by the superposition of reference porphyrin (ref-H2P) and cupshaped nanocarbons. The photoexcitation of the CNC-(H2P)n nanohybrid results in formation of the charge-separated (CS) state to attain the longest CS lifetime (0.64 ± 0.01 ms) ever reported for donor-acceptor nanohybrids, which may arise from efficient electron migration following the charge séparation. The formation of a radical ion pair was detected directly by electron spin resonance (ESR) measurements under photoirradiation of CNC(H 2P)n with a high-pressure mercury lamp in frozen DMF at 153 K. The observed ESR signal at g = 2.0044 agrees with that of TCf-H 2P"1" produced by one-electron oxidation with [Ru(bpy) 3]3+ in deaerated CHCl3, indicating the formation of H2P"1". The electron-acceptor ability of the reference CNC compound (ref-CNC) was also examined by the electron-transfer reduction of ref-CNC by a series of semiquinone radical anions.
AB - Cup-shaped nanocarbons (CNC) generated by the electron-transfer reduction of cup-stacked carbon nanotubes have been functionalized with porphyrins (H 2P) as light-capturing chromophores. The resulting donor-acceptor nanohybrid has been characterized by thermogravimetric analysis (TGA), Raman and IR spectroscopy, transmission electron microscopy, elemental analysis, and UV/Vis spectroscopy. The weight of the porphyrins attached to the cup-shaped nanocarbons was determined as 20% by TGA and elemental analysis. The UV/Vis absorption spectrum of CNC-(H2P)n in DMF agrees well with that obtained by the superposition of reference porphyrin (ref-H2P) and cupshaped nanocarbons. The photoexcitation of the CNC-(H2P)n nanohybrid results in formation of the charge-separated (CS) state to attain the longest CS lifetime (0.64 ± 0.01 ms) ever reported for donor-acceptor nanohybrids, which may arise from efficient electron migration following the charge séparation. The formation of a radical ion pair was detected directly by electron spin resonance (ESR) measurements under photoirradiation of CNC(H 2P)n with a high-pressure mercury lamp in frozen DMF at 153 K. The observed ESR signal at g = 2.0044 agrees with that of TCf-H 2P"1" produced by one-electron oxidation with [Ru(bpy) 3]3+ in deaerated CHCl3, indicating the formation of H2P"1". The electron-acceptor ability of the reference CNC compound (ref-CNC) was also examined by the electron-transfer reduction of ref-CNC by a series of semiquinone radical anions.
KW - Donor-acceptor systems
KW - Electron transfer
KW - Nanotubes porphyrinoids
KW - Redox chemistry
UR - http://www.scopus.com/inward/record.url?scp=70349103832&partnerID=8YFLogxK
U2 - 10.1002/chem.200900427
DO - 10.1002/chem.200900427
M3 - Article
AN - SCOPUS:70349103832
SN - 0947-6539
VL - 15
SP - 9160
EP - 9168
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
IS - 36
ER -