Creation of Solid State Shearchromism by Shear Stress Effects

研究了剪切应力对光致变色螺吡喃的影响。我们使用了蓝宝石压砧与旋转机制，并进行了原位观察显微镜下的拉曼光谱测量。这一结果将有助于“剪切变色”的发展和控制化学键的新方法.剪切应力效应6-硝基螺吡喃薄膜在剪切变形作用下颜色由浅黄色明显变为绿色。对于绿色态，由于荧光较强，无法获得拉曼光谱。随着应力的释放，荧光发射消失，颜色由绿色变为紫色。紫色态的光谱是螺吡喃的光谱，有一些新的叠加弱带。这些谱带表明，一些螺吡喃分子转化为mercury。在2.5GPa以上的流体静压下，也观察到了向绿色态的变色行为和较强的荧光，这一数值大于估计的剪切应力1GPa。剪切应力比压力对分子的变形更有效.光响应特性在环境压力下，6-硝基螺吡喃的薄膜在紫外光下很容易从黄色变为紫色，在可见光下恢复为黄色。然而，在剪切应力下的绿色状态在UV光照射后保持，并且在可见光下略微褪色。剪切变形下的螺吡喃类化合物对光的响应较小.环糊精包合物6-硝基螺吡喃在γ-环糊精中的包合物在剪切应力作用下呈现由粉红色到暗红色的显色行为，在释放应力作用下呈现红紫色的显色行为。拉曼光谱表明，在剪切应力诱导下，汞分子被稳定在γ-环糊精中。此外，观察到比独立的螺吡喃更快的光致变色行为。

The shear stress effects on the photochromic spiropyrans have been studied. We have used the sapphire anvil cell with the rotation mechanism and performed the in situ observations under a microscope with Raman spectroscopic measurements. The results should be led to the development of “shearchromism" and the new method for controlling chemical bonds.1. Shear stress effectsThe color of the thin film of 6-nitrospiropyran was remarkably changed from light-yellow to green under shear deformation. For the green state, the Raman spectrum could not be obtained because of the strong fluorescence. As being released stress, the color changed from green to purple and the fluorescent emission disappeared. The spectrum of the purple state was that of spiropyran with some new superimposed weak bands. These bands suggest that some spiropyran molecules are transformed to merocyanine. The chromic behavior to the green state and the strong fluorescence were observed also by the hydrostatic pressure over about 2.5GPa, which was larger than the estimated shear stress 1GPa. The shear stress gave more effective deformation to molecules than pressure.2. Photoresponsive propertiesThe thin film of 6-nitrospiropyran at ambient pressure was readily changed from yellow to purple with UV light and returned to yellow with visible light. However, the green state under shear stress remained after the irradiation of UV light and slightly faded with visible light. Spiropyrans under shear deformation less responded to the light.3. Cyclodextrin inclusion compoundThe inclusion compound of 6-nitrospiropyran in y-cyclodextrin has exhibited the chromic behavior from pink to dark red by shear stress and then to red-purple as releasing stress. Raman spectra showed that the transformation to merocyanine was induced under shear stress and that merocyanine molecule was stabilized in y-cyclodextrin. In addition, the more rapid photochromic behavior than independent spiropyran was observed.