Thefioux Yaouen, Cordier Marie, Massuyeau Florian, Latouche Camille, Martineau-Corcos Charlotte, Perruchas Sandrine
Université de Nantes, CNRS, Institut des Matériaux Jean Rouxel, IMN, F-44000 Nantes, France.
Université de Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes), UMR 6226, F-35000 Rennes, France.
Inorg Chem. 2020 Apr 20;59(8):5768-5780. doi: 10.1021/acs.inorgchem.0c00560. Epub 2020 Apr 1.
The photoluminescent stimuli-responsive properties of two crystalline polymorphs with the formula (PPh)[CuI] are reported. Distinct luminescence properties are exhibited by these ionic copper iodide compounds with blue or yellow emission, and original luminescence thermochromism and mechanochromism are demonstrated. While one polymorph displays contrasted temperature-dependent emission properties, the other shows great modification of its emission upon mechanical solicitation. The establishment of structure-properties relationships, supported by a theoretical approach, permits us to get insights into the origin of the photoluminescence properties and the mechanisms at play. According to DFT calculations, the different emission bands originate either from the (PPh) organic cation or from the [CuI] anion. Activation of these two emissive centers appears to be dependent on the crystalline packing of the polymorph. The thermochromism displayed by one polymorph can be attributed to a variation in temperature of the relative intensities of two emission bands of two different excited states. The origin is different for the other polymorph, with emission bands coming from two independent emissive centers: namely, (PPh) and [CuI]. The luminescence mechanochromism is attributed to a polymorphic transition. The mechanical solicitation induces a partial transformation of one polymorph into the other within a disordered phase. The mechanochromic mechanism can be related to mechanical modifications of intermolecular interactions between the (PPh) cations. By displaying luminescence properties that depend on crystalline structure, excitation wavelength, temperature, and mechanical solicitation, the studied copper iodides offer a great possibility of emissive color control and switching, a clear demonstration of the great potentialities of this family of compounds for the development of photoactive materials.
报道了两种分子式为(PPh)[CuI]的晶体多晶型物的光致发光刺激响应特性。这些离子型碘化铜化合物表现出不同的发光特性，发出蓝色或黄色光，并展示出原始的发光热致变色和机械变色现象。一种多晶型物表现出与温度相关的对比性发射特性，而另一种在机械作用下其发射有很大变化。在理论方法的支持下建立结构-性质关系，使我们能够深入了解光致发光特性的起源和起作用的机制。根据密度泛函理论(DFT)计算，不同的发射带要么来自(PPh)有机阳离子，要么来自[CuI]阴离子。这两个发射中心的激活似乎取决于多晶型物的晶体堆积。一种多晶型物显示的热致变色可归因于两种不同激发态的两个发射带相对强度的温度变化。另一种多晶型物的起源不同，其发射带来自两个独立的发射中心，即(PPh)和[CuI]。发光机械变色归因于多晶型转变。机械作用诱导一种多晶型物在无序相内部分转变为另一种多晶型物。机械变色机制可能与(PPh)阳离子之间分子间相互作用的机械改变有关。通过展示取决于晶体结构、激发波长、温度和机械作用的发光特性，所研究的碘化铜为发光颜色控制和切换提供了很大可能性，清楚地证明了这类化合物在光活性材料开发方面的巨大潜力。
