Abstract
Regioselective alkylation of 1-(4-pyridyl)-2-[5-(dicyanomethanide)thien-2-yl]ethylene sodium salt (2) by a covalently surface-bound benzylhalide (4) produces a polar-ordered zwitterionic thin film (5). Chemisorption of 2 on the coupling layer 4 was monitored by UV-vis spectroscopy, contact-angle measurements, X-ray photoelectron spectroscopy, and second harmonic generation (SHG). Relative to carbanion 2, the film UV-vis spectrum exhibits a red-shifted (Δλ ∼ 170 nm) charge-transfer band, consistent with quaternization of the pyridyl group of 2 by 4. The nonlinear optical properties of the blue films of 5 were measured by SHG. The average molecular tilt angle of the chromophore was determined to be ∼46°, and χZZZ(2) ∼ 5.0 × 10-8 esu (∼20 pm/V) was estimated at a fundamental wavelength of 1064 nm.
Original language | English |
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Pages (from-to) | 5939-5942 |
Number of pages | 4 |
Journal | Langmuir |
Volume | 17 |
Issue number | 19 |
DOIs | |
Publication status | Published - Sep 18 2001 |
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Colloid and Surface Chemistry