As a potential material for use in optical fiber fluorescence sensors for rapid detection of saxitoxin, 9-(monoaza-18-crown-6-methyl)-10-hexadecylanthracene (CAC16) was synthesized, and the interfacial and spectroscopic properties of the Langmuir monolayers and Langmuir-Schaefer films of CAC16 were studied. The surface pressure-area and surface potential-area isotherms of CAC16 on different subphases were obtained. An increased limiting molecular area was observed on a pH 2 subphase. In situ fluorescence emission spectra (λex = 366 nm) of the CAC16 monolayer showed a broad fluorescence band on a pH 2 subphase but none on a pure water subphase. Mixed monolayers of CAC16/C20 (arachidic acid) on a pure water subphase showed an increased fluorescence emission intensity of anthracene with an increase in the proportion of C20. This suggests that the low fluorescence activity of the pure CAC16 monolayer could be caused by self-quenching due to the high concentration of CAC16 at the interface. In a mixed monolayer, C20 acts as a two-dimensional solvent to dilute CAC16 and diminish the self-quenching, thus recovering the fluorescence activity of CAC16. When CAC16 was mixed with C18OH (stearyl alcohol), the monolayers showed no fluorescence signal, regardless of the C18OH content. Analysis of the surface pressure-area isotherms showed that CAC16 is not miscible with C18OH. Langmuir-Schaefer films of CAC16/C20 showed better anthracene emission spectra than the monolayers at the air-water interface.
|Original language||English (US)|
|Number of pages||6|
|State||Published - Jan 1 2000|
ASJC Scopus subject areas
- Materials Science(all)
- Condensed Matter Physics
- Surfaces and Interfaces