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Two‐Dimensionally Extended Porphyrin Tapes: Synthesis and Shape‐Dependent Two‐Photon Absorption Properties
Author(s) -
Nakamura Yasuyuki,
Jang So Young,
Tanaka Takayuki,
Aratani Naoki,
Lim Jong Min,
Kim Kil Suk,
Kim Dongho,
Osuka Atsuhiro
Publication year - 2008
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.200800776
Subject(s) - trimer , porphyrin , tetramer , absorption (acoustics) , materials science , two photon absorption , absorption cross section , crystallography , wavelength , photochemistry , chemistry , cross section (physics) , optics , dimer , physics , organic chemistry , composite material , optoelectronics , laser , quantum mechanics , enzyme
We report the synthesis and characterization of L‐ and T‐shaped porphyrin tapes as extensible structural motifs of two‐dimensionally extended porphyrin tapes. The two‐photon absorption (TPA) cross‐section values ( σ (2) ) for L‐ and T‐shaped porphyrin tapes as well as those for linear trimeric and tetrameric porphyrin tapes were measured by an open‐aperture Z‐scan method at 2300 nm, a wavelength at which the one‐photon absorption contribution is either zero or almost negligible. Under these conditions, the σ (2) values for the linear porphyrin tape trimer and tetramer were determined to be 18 500 and 41 200 GM, respectively. The σ (2) value for the L‐shaped trimer was determined to be 8700 GM, which is only half that of the linear trimer, whereas the σ (2) value for the T‐shaped tetramer was measured to be 35 700 GM. These results clearly indicate the dependence of the TPA cross‐section on the molecular shape, which underscores the importance of directionality in the π‐conjugation pathway for the enhancement of TPA cross‐ section.