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Functionalization of Diameter‐Sorted Semiconductive SWCNTs with Photosensitizing Porphyrins: Syntheses and Photoinduced Electron Transfer
Author(s) -
Das Sushanta K.,
Sandanayaka Atula S. D.,
Subbaiyan Navaneetha K.,
Zandler Melvin E.,
Ito Osamu,
D'Souza Francis
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201200970
Subject(s) - thermogravimetric analysis , photoinduced charge separation , photochemistry , surface modification , porphyrin , ultrafast laser spectroscopy , photoinduced electron transfer , raman spectroscopy , absorption (acoustics) , quenching (fluorescence) , chemistry , fluorescence , excited state , radical ion , singlet state , electron transfer , covalent bond , nanosecond , materials science , ion , photocatalysis , spectroscopy , organic chemistry , artificial photosynthesis , catalysis , atomic physics , laser , optics , composite material , quantum mechanics , physics
Covalent functionalization of diameter sorted SWCNTs with porphyrins (MP), and photochemistry to establish nanotube diameter‐dependent charge separation efficiencies are reported. The MP–SWCNT( n , m ) [M=2 H or Zn, and ( n , m )=(7,6) or (6,5)] nanohybrids are characterized by a variety of spectroscopic, thermogravimetric, TEM imaging techniques, and also by DFT MO calculations. The thermogravimetric, Raman and fluorescence studies reveal the presence of a moderate number of porphyrins on the SWCNT surface. The MO results suggest charge separation (CS) via the excited state of MP. Time‐resolved fluorescence studies reveal quenching of the singlet excited state of the MP with SWCNT( n , m ), giving the rate constants of charge separation ( k CS ) in the range of (4–5)×10 9 s −1 . Nanosecond transient absorption measurements confirm the charge‐separated radical cation and the radical anion as [MP .+ –SWCNT .− ] with their characteristic absorption bands in the visible and near‐IR regions. The charge separated states persist for about 70–100 ns thus giving an opportunity to utilize them to build photoelectrochemical cells, which allowed us to derive the structure–reactivity relationship between the nature of porphyrin and diameter of the employed nanotubes.