Dual emitting Langmuir-Blodgett films of cationic iridium complexes and montmorillonite clay for oxygen sensing
Dual emitting Langmuir-Blodgett films of cationic iridium complexes and montmorillonite clay for oxygen sensing
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DOI：
10.1039/c2nj40351j
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发表时间：
2012-12-01
影响因子：
3.3
通讯作者：
Sato, Hisako
中科院分区：
文献类型：
--
作者：
Morimoto, Kazuya;Nakae, Takahiro;Sato, Hisako
通过将两亲性阳离子铱（Ⅲ）配合物的漂浮单分子层与亚相中的黏土颗粒杂化制备了朗缪尔 - 布洛杰特（LB）膜。使用了两种铱（Ⅲ）配合物：[Ir(dfppy)₂(dc9bpy)]⁺（用DFPPY表示：dfppyH = 2 -（4',6' - 二氟 - 苯基）吡啶；dc9bpy = 4,4' - 二壬基 - 2,2' - 联吡啶），其最大发射波长（λₘₐₓ）在500 nm，以及[Ir(ppy)₂(dc9bpy)]⁺（用PPY表示：ppyH = 2 - 苯基吡啶），其λₘₐₓ在550 nm。在真空下对以下薄膜记录了稳态发射光谱：{DFPPY或PPY/黏土}ₙ（n = 1 - 3），{DFPPY/黏土/PPY/黏土}和{PPY/黏土/DFPPY/黏土}。{PPY/黏土}ₙ或{DFPPY/黏土}ₙ的发射强度几乎与层数（n）成正比。在{DFPPY/黏土/PPY/黏土}中DFPPY和PPY同时发射，表明能量转移的贡献较低。相反，在{PPY/黏土/DFPPY/黏土}中只有PPY发射，这是由于上层的PPY对下层激发态的DFPPY有效猝灭的结果。引入氧气导致所有薄膜的发射降低。值得注意的是，{DFPPY/黏土/PPY/黏土}在氧气气氛下呈现出双发射特性，即在较低氧气压力（0 < P - O₂ < 4 kPa）下，在530 nm左右观察到宽发射峰，而在较高氧气压力（P - O₂ > 4 kPa）下，发射峰移至550 nm。
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',6'-difluoro-phenyl)pyridine; dc9bpy = 4,4'-dinonyl-2,2'-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 < P-O2 < 4 kPa), while the emission peak shifted to 550 nm at higher oxygen pressure (P-O2 > 4 kPa).