Hybrid nanostructures with switchable and reversible "blue-red-green" emission were efficiently synthesized. These nanostructures comprise polyhedral oligomeric silsesquioxanes (POSS) that behave as a nanocage that can be functionalized with terpyridine-based organic ligands, which can be easily complexed with europium (III) ions. The complexes were characterized by UV-Vis and fluorescence spectroscopy and their stoichiometry was also confirmed by 1 H NMR spectroscopy. In the presence of the Eu(III) ions, the octafunctionalized nanocages self-assemble to form 3D architectures that display an intense red-emission, especially in the solid state. The presence of an alkenyl group bridging the inorganic core to the organic moiety was employed to tune the emission properties by trans-cis isomerization of the double bond. In the case of the octafunctionalized nanocages (O-POSS), this isomerization was monitored in the presence of Eu(III) cations and was accompanied by an evident colour change from blue (trans-O-POSS) to red (Eu@trans-O-POSS) and finally to green (cis-O-POSS) as consequence of the release of the metal cations. This behaviour, together with the easy dispersion of the dry powder and the possibility of coating as a film in presence of small amounts of solvent, makes the emissive solid promising for applications in materials science.

中文翻译：

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在Euro（III）离子存在下自组装的基于多面体低聚倍半硅氧烷的纳米结构的可调谐发射：可逆的反式-顺式异构化。

有效地合成了具有可切换和可逆的“蓝-红-绿”发射的杂化纳米结构。这些纳米结构包含多面体低聚倍半硅氧烷（POSS），其表现为可以被基于三联吡啶的有机配体官能化的纳米笼，该配体可以很容易地与III（III）离子络合。通过UV-Vis和荧光光谱对复合物进行表征，并且通过1 H NMR光谱也证实了其化学计量。在Eu（III）离子存在的情况下，八官能化的纳米笼自组装形成3D结构，该结构显示出强烈的红色发射，特别是在固态下。利用桥接无机核心至有机部分的烯基的存在，通过双键的反式-顺式异构化来调节发射性质。在八官能化纳米笼（O-POSS）的情况下，在Eu（III）阳离子存在的情况下监测了这种异构化，并伴随着明显的颜色变化，从蓝色（trans-O-POSS）变为红色（Eu @ trans- O-POSS），最后由于金属阳离子的释放而变成绿色（顺式-O-POSS）。这种行为，加上干粉易于分散，以及在少量溶剂存在下涂成薄膜的可能性，使发射性固体有望在材料科学中应用。