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Covalent Functionalization of Carbon Nanohorns with Porphyrins: Nanohybrid Formation and Photoinduced Electron and Energy Transfer
Author(s) -
Pagona G.,
Sandanayaka A. S. D.,
Araki Y.,
Fan J.,
Tagmatarchis N.,
Charalambidis G.,
Coutsolelos A. G.,
Boitrel B.,
Yudasaka M.,
Iijima S.,
Ito O.
Publication year - 2007
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200700039
Subject(s) - photochemistry , electron transfer , materials science , ultrafast laser spectroscopy , quenching (fluorescence) , singlet state , photoexcitation , porphyrin , covalent bond , high resolution transmission electron microscopy , excited state , viologen , chemistry , transmission electron microscopy , fluorescence , nanotechnology , spectroscopy , organic chemistry , physics , quantum mechanics , nuclear physics
The covalent attachment of carbon nanohorns (CNHs) to α‐5‐(2‐aminophenyl)‐α‐15‐(2‐nitrophenyl)‐10,20‐bis(2,4,6‐trimethyl‐phenyl)‐porphyrin (H 2 P) via an amide bond is accomplished. The resulting CNH–H 2 P nanohybrids form a stable inklike solution. High‐resolution transmission electron microscopy (HRTEM) images demonstrate that the original dahlia‐flowerlike superstructure of the CNHs is preserved in the CNH–H 2 P nanohybrids. Steady‐state and time‐resolved fluorescence studies show efficient quenching of the excited singlet state of H 2 P, suggesting that both electron and energy transfer occur from the singlet excited state of H 2 P to CNHs, depending on the polarity of the solvent. In the case of electron transfer, photoexcitation of H 2 P results in the reduction of the nanohorns and the simultaneous oxidation of the porphyrin unit. The formation of a charge‐separated state, CNH • – –H 2 P • + , has been corroborated with the help of an electron mediator, hexyl‐viologen dication (HV 2+ ), in polar solvents. Moreover, the charge‐separated CNH • – –H 2 P • + states have been identified by transient absorption spectroscopy.