Dual emitting Langmuir-Blodgett films of cationic iridium complexes and montmorillonite clay for oxygen sensing

作者：Morimoto Kazuya; Nakae Takahiro; Ohara Keishi; Tamura Kenji; Nagaoka Shin ichi; Sato Hisako^*

来源：New Journal of Chemistry, 2012, 36(12): 2467-2471.

DOI：10.1039/c2nj40351j

Langmuir-Blodgett (LB) films were prepared by hybridizing a floating monolayer of an amphiphilic cationic iridium(m) complex with clay particles in a subphase. Two kinds of iridium(III) complexes were used: [Ir(dfppy)(2)(dc9bpy)](+) (denoted by DFPPY: dfppyH = 2-(4%26apos;,6%26apos;-difluoro-phenyl)pyridine; dc9bpy = 4,4%26apos;-dinonyl-2,2%26apos;-bipyridine) with the maximum emission wavelength (lambda(max)) at 500 nm and [Ir(ppy)(2)(dc9bpy)](+) (denoted by PPY: ppyH = 2-phenylpyridine) with lambda(max) at 550 nm. Stationary emission spectra were recorded on the following films under vacuum: {DFPPY or PPY/clay}(n) (n = 1-3), {DFPPY/clay/PPY/clay} and {PPY/clay/DFPPY/clay}. The intensity of emission from {PPY/clay}(n) or {DFPPY/clay}(n) increased nearly in proportion to the layer number (n). Both DFPPY and PPY emitted simultaneously from {DFPPY/clay/PPY/clay}, indicating the low contribution of energy transfer. Contrarily PPY emitted exclusively from {PPY/clay/DFPPY/clay} as a result of the efficient quenching of excited DFPPY in the lower layer by PPY in the upper layer. The introduction of oxygen gas resulted in the decrease of emission for all films. Notably {DFPPY/clay/PPY/clay} exhibited a dual emitting character under an oxygen atmosphere, that is, the broad emission maximum was observed around 530 nm at lower oxygen pressure (0 %26lt; P-O2 %26lt; 4 kPa), while the emission peak shifted to 550 nm at higher oxygen pressure (P-O2 %26gt; 4 kPa).

• 出版日期2012-12