Synthesis and Photophysics of Quaterrylene Molecules in Single-Walled Carbon Nanotubes: Excitation Energy Transfer between a Nanoscale Cylinder and Encapsulated Molecules
journal contributionposted on 18.09.2014, 00:00 by Takeshi Koyama, Takuya Tsunekawa, Takeshi Saito, Koji Asaka, Yahachi Saito, Hideo Kishida, Arao Nakamura
We report the synthesis of quaterrylene monomers and dimers from perylene inside single-walled carbon nanotubes (SWNTs). Excitation energy transfer (EET) from the encapsulated molecule to the SWNT is investigated by using femtosecond pump–probe spectroscopy and time-resolved luminescence spectroscopy. Optical spectroscopy and transmission electron microscopy reveal the molecular arrangement of quaterrylene monomers and dimers within the SWNTs. The observed EET time from the dipole-allowed excited state of the quaterrylene monomer to the SWNT depends on the tube diameter and is found to be 1.1 ± 0.2 ps and 0.4 ± 0.1 ps for average diameters of 1.4 and 1.8 nm, respectively. These transfer times are ascribed to EET via a Coulomb interaction between transition dipoles. The transfer time from the dipole-forbidden state of the dimer to the SWNT with an average diameter of 1.8 nm is 3.8 ± 0.2 ps. The EET mechanism presumably corresponds to electron exchange or Coulomb interactions involving higher multipoles.