Isomerization, Protonation, and Hydrolysis Properties of Naphthalimide-Containing Spiropyran in Aqueous Media.

作者：Y. Shiraishi, Taku Oshima, T. Hirai · 发表于：Journal of Physical Chemistry B · 年份：2024 · DOI：10.1021/acs.jpcb.4c03894 · 被引用次数：8 · 研究领域：Medicine

Synthesis of spiropyrans exhibiting ring-opening/closing isomerization driven by external stimuli is a challenging subject for the development of molecular sensors. A napthalimide-containing spiropyran (1) promotes rapid isomerization between the spirocyclic (SP) form and ring-opened merocyanine (MC) form by the change in solvent polarity even under the dark condition at room temperature. In this work, the effect of water on the isomerization behavior of 1 was studied. The addition of water caused an MC-water H-bonding interaction and shifted the resonance MC structure to the zwitterionic form with a lower ground-state energy. The stabilized MC form promoted spontaneous SP → MC isomerization and increased the equilibrium MC concentration. The effect of pH on the behavior of 1 was also studied. In acidic-neutral media, protonation/deprotonation of the naphthalimide moiety led to rapid and reversible changes in the absorption spectra. In contrast, strongly basic media (pH > 12) promoted irreversible base-catalyzed hydrolysis of the alkene moiety.