Colaço Melwin, Carletta Andrea, Van Gysel Mégane, Robeyns Koen, Tumanov Nikolay, Wouters Johan
Department Chemistry St. Joseph's College, Box 27094 560 027 Bangalore India.
Department Chemistry UNamur 61 Rue de Bruxelles 5000 Namur Belgium.
ChemistryOpen. 2018 Jul 2;7(7):520-526. doi: 10.1002/open.201800082. eCollection 2018 Jul.
Direct access to the protonated merocyanine forms of two substituted spiropyrans by mechanosynthesis or sonochemistry was explored. The compounds were formed by the condensation reaction of the methyleneindolium iodide salt with salicylaldehyde derivatives. X-ray crystallography, H NMR spectroscopy, ab initio geometry optimization, and absorption spectroscopy were combined to provide a better understanding of the four-state molecular switch system in which the newly synthesized protonated merocyanines were found to play a central role. The results of this study suggest that the stability of the protonated merocyanines requires acidic conditions, as treatment with base led to the corresponding unprotonated merocyanines, which in turn spontaneously converted into photochromic closed spiropyrans.
通过机械合成或声化学方法直接获得两种取代螺吡喃的质子化部花青形式进行了探索。这些化合物是由亚甲基吲哚碘盐与水杨醛衍生物的缩合反应形成的。结合X射线晶体学、氢核磁共振光谱、从头算几何优化和吸收光谱，以更好地理解四态分子开关系统，其中发现新合成的质子化部花青起着核心作用。本研究结果表明，质子化部花青的稳定性需要酸性条件，因为用碱处理会导致相应的未质子化部花青，而后者又会自发转化为光致变色的闭环螺吡喃。
