Guo Xuefeng, Zhou Yucheng, Zhang Deqing, Yin Bing, Liu Zhiliang, Liu Caiming, Lu Zhengliang, Huang Yuanhe, Zhu Daoben
Center for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China.
J Org Chem. 2004 Dec 10;69(25):8924-31. doi: 10.1021/jo0487799.
A new spiropyran (SP2) with the stable merocyanine form (MC2) both in solution and in the solid state at room temperature was designed and synthesized. The stability of MC2 is believed to be due to the electron-withdrawing effect of both the quinoline and the trifluoromethyl groups. (1)H NMR spectra indicate that the ratio of the open form vs the closed form of SP2 is dependent on the polarity of solvents. Single crystals composed of only the open form (MC2) were successfully obtained. X-ray structural analysis indicates that except trifluoromethyl and two methyl groups MC2 is completely planar with an s-trans,s-cis conformation. It should be noted that this is the first report of the X-ray crystal structure of the pure open form of spiropyran. MC2 can be slowly transformed into SP2 at -30 degrees C or lower temperature, and the process is accelerated by visible light irradiation. This special photochromic behavior can be explained by the calculated thermodynamic data. The spectral properties of SP2/MC2 in the presence of different metal ions are also studied, and the results show the potential application of SP2/MC2 in sensing metal ions.
设计并合成了一种新型螺吡喃（SP2），其在室温下于溶液和固态中均具有稳定的部花青形式（MC2）。据信MC2的稳定性归因于喹啉和三氟甲基的吸电子效应。核磁共振氢谱表明SP2的开环形式与闭环形式的比例取决于溶剂的极性。成功获得了仅由开环形式（MC2）组成的单晶。X射线结构分析表明，除三氟甲基和两个甲基外，MC2呈完全平面状，具有s-反式，s-顺式构象。应当指出，这是关于螺吡喃纯开环形式的X射线晶体结构的首次报道。在-30℃或更低温度下，MC2可缓慢转化为SP2，且该过程可通过可见光照射加速。这种特殊的光致变色行为可用计算得到的热力学数据来解释。还研究了SP2/MC2在不同金属离子存在下的光谱性质，结果表明SP2/MC2在传感金属离子方面具有潜在应用。
