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Synthesis, Spectroscopic and Nonlinear Optical Properties of Multiple [60]Fullerene–Oligo( p ‐phenylene ethynylene) Hybrids
Author(s) -
Zhao Yuming,
Shirai Yasuhiro,
Slepkov Aaron D.,
Cheng Long,
Alemany Lawrence B.,
Sasaki Takashi,
Hegmann Frank A.,
Tour James M.
Publication year - 2005
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.200401198
Subject(s) - fullerene , phenylene , ground state , conjugated system , excited state , absorption (acoustics) , chemistry , materials science , photochemistry , crystallography , organic chemistry , atomic physics , physics , polymer , composite material
A series of multiple [60]fullerene terminated oligo( p ‐phenylene ethynylene) (OPE) hybrid compounds has been synthesized through a newly developed in situ ethynylation method. Structural and magnetic shielding properties of the highly unsaturated carbon‐rich C 60 and OPE scaffolds were characterized by 1D and 2D NMR spectroscopic analyses. Electronic interactions between the [60]fullerenes and the OPE backbones were investigated by UV/Vis spectroscopic and cyclic voltammetry (CV) experiments. Our studies clearly show that although the multiple [60]fullerene groups are connected via π‐conjugated OPE frameworks, they present diminutive electronic interactions in the ground state, and the electronic behavior of the [60]fullerene cages are only affected by the OPE backbones through modest inductive effects. Interestingly, sizable third‐order nonlinear optical (NLO) responses ( γ ) and enhanced two‐photon absorption (TPA) cross‐sections ( σ (2) ) were determined for the multifullerene–OPE hybrid 31 relative to its OPE precursor from differential optical Kerr effect (DOKE) experiments. Such enhanced NLO performance is presumably due to the occurrence of periconjugation and/or charge transfer effects in the excited state. In addition, comparatively strong excited‐state absorption was observed and characterized for OPE pentamer 12 . Thus, the use of such fullerene‐derivatized conjugated oligomers aids the quest for molecules with large third‐order NLO and TPA properties.