Langmuir-Blodgett Films of Charge-Transfer Complexes between an Amphiphilic Monopyrrolo-TTF and TCNQ Derivatives

Tomoyuki Akutagawa, Masanori Uchigata, Tatsuo Hasegawa, Takayoshi Nakamura, Kent A. Nielsen, Jan O. Jeppesen, Thomas Brimert, Jan Becher

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15 Citations (Scopus)

Abstract

Electrically active Langmuir-Blodgett (LB) films based on charge-transfer (CT) complexes between an amphiphilic monopyrrolo-tetrathiafulvalene (MP-TTF) electron donor and different derivatives of the electron acceptor 7,7,8,8-tetracyano-p-quinodimethane (TCNQ), namely, 2,5-difluoro-TCNQ, fluoro-TCNQ, TCNQ, decyl-TCNQ, 2,5-dimethyl-TCNQ, and 2-methoxy-5-ethoxy-TCNQ, have been fabricated and investigated systematically. The electronic ground state of the CT complex, (MP-TTF)(TCNQs), in the LB films varied from ionic (δ = 1) to neutral (δ ∼ 0) depending on the electron affinity of the TCNQ derivative used. CT excitation energies of the LB films were correlated against the difference between the redox potentials of the MP-TTF and TCNQ derivatives, exhibiting agreement with a neutral-ionic (N-I) phase diagram proposed for mixed-stack CT complexes. Of the six kinds of LB films, the (MP-TTF+0.3)(decyl-TCNQ -0.3) and (MP-TTF+0.6)(TCNQ-0.6) complexes were located closest to the N-I phase boundary. In all of the LB films, the CT transition moment was found to be parallel to the substrate surface based on information from polarized UV-vis-NIR, IR transmission, and reflection-absorption spectra. After being transferred onto a mica surface by a single withdrawal, the surface morphologies of the films were found to be uniform or exhibited spongelike domain structures of thickness about 1.8 nm.

Original languageEnglish
Pages (from-to)13929-13938
Number of pages10
JournalJournal of Physical Chemistry B
Volume107
Issue number50
DOIs
Publication statusPublished - 2003 Dec 18
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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