Thermal isomerization of spiropyran to merocyanine in aqueous media and its application to colorimetric temperature indication
Thermal isomerization of spiropyran to merocyanine in aqueous media and its application to colorimetric temperature indication
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DOI：
10.1039/c0cp00140f
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发表时间：
2010-01-01
影响因子：
3.3
通讯作者：
Hirai, Takayuki
中科院分区：
文献类型：
--
作者：
Shiraishi, Yasuhiro;Itoh, Masataka;Hirai, Takayuki
研究了螺吡喃衍生物在水介质中的热致异构化反应。螺吡喃衍生物的无色螺环(SP)形式在高温下即使在黑暗条件下也能异构化为有色花菁(MC)形式。平衡实验、动力学实验和氢气实验表明，SP->；MC的热异构化是由于与水分子的氢键作用使MC形态稳定。这导致MC形式的基态能量降低到低于SP形式的基态能量，从而导致SP->；MC异构化。热异构化性质适用于溶液温度的大致指示。螺吡喃衍生物在适当光强的可见光照射下溶解在水介质中时，随着温度的升高，MC吸光度增加。无论加热/冷却顺序如何，都会发生可逆的吸收响应。因此，螺吡喃衍生物有可能用于比色测温。
Thermally-induced isomerization of spiropyran derivatives in aqueous media has been studied. The colorless spirocyclic (SP) forms of spiropyran derivatives are isomerized to colored merocyanine (MC) forms even in dark conditions at elevated temperature. Equilibrium, kinetic, and deuterium experiments reveal that the thermal SP -> MC isomerization is due to the stabilization of MC form by a hydrogen bonding interaction with water molecules. This leads to the ground state energy of the MC form decreasing to lower than that of the SP form, resulting in SP -> MC isomerization. The thermal isomerization property is applicable to a rough indication of solution temperature. The spiropyran derivatives, when dissolved in aqueous media under irradiation of visible light with an appropriate light intensity, demonstrate an increase in MC absorbance with a rise in temperature. The absorption response occurs reversibly regardless of the heating/cooling sequence. The spiropyran derivatives therefore have a potential for colorimetric temperature indication.