title: Synthesis, spectroscopic and nonlinear optical properties of multiple [60]fullerene-oligo(p-phenylene ethynylene) hybrids.
abstract: 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 pi-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 (gamma) and enhanced two-photon absorption (TPA) cross-sections (sigma((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.
authors.affiliation: Department of Chemistry, Center for Nanoscale Science and Technology, Rice University, Houston, TX 77005, USA.
authors.forename: Yuming
authors.initials: Y
authors.lastname: Zhao
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Shirai
authors.forename: Aaron D
authors.initials: AD
authors.lastname: Slepkov
authors.forename: Long
authors.initials: L
authors.lastname: Cheng
authors.forename: Lawrence B
authors.initials: LB
authors.lastname: Alemany
authors.forename: Takashi
authors.initials: T
authors.lastname: Sasaki
authors.forename: Frank A
authors.initials: FA
authors.lastname: Hegmann
authors.forename: James M
authors.initials: JM
authors.lastname: Tour
mesh_terms: D037741:Fullerenes / Q000737:chemistry*; D015394:Molecular Structure; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry
chemical_list: D037741:Fullerenes; D011108:Polymers; C473966:poly(phenylene ethynylene); C069837:fullerene C60