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Issue 12, 2012
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Dual emitting Langmuir–Blodgett films of cationic iridium complexes and montmorillonite clay for oxygen sensing

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Abstract

Langmuir–Blodgett (LB) films were prepared by hybridizing a floating monolayer of an amphiphilic cationic iridium(III) 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′,6′-difluoro-phenyl)pyridine; dc9bpy = 4,4′-dinonyl-2,2′-bipyridine) with the maximum emission wavelength (λmax) at 500 nm and [Ir(ppy)2(dc9bpy)]+ (denoted by PPY: ppyH = 2-phenylpyridine) with λmax 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 < PO2 < 4 kPa), while the emission peak shifted to 550 nm at higher oxygen pressure (PO2 > 4 kPa).

Graphical abstract: Dual emitting Langmuir–Blodgett films of cationic iridium complexes and montmorillonite clay for oxygen sensing

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Publication details

The article was received on 04 May 2012, accepted on 03 Sep 2012 and first published on 25 Sep 2012


Article type: Paper
DOI: 10.1039/C2NJ40351J
Citation: New J. Chem., 2012,36, 2467-2471
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    Dual emitting Langmuir–Blodgett films of cationic iridium complexes and montmorillonite clay for oxygen sensing

    K. Morimoto, T. Nakae, K. Ohara, K. Tamura, S. Nagaoka and H. Sato, New J. Chem., 2012, 36, 2467
    DOI: 10.1039/C2NJ40351J

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