Tuning the Negative Photochromism of Water-Soluble Spiropyran Polymers
Tuning the Negative Photochromism of Water-Soluble Spiropyran Polymers
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DOI：
10.1021/acs.macromol.8b01915
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发表时间：
2018-10-23
期刊：
影响因子：
5.5
通讯作者：
Thomas, Samuel W., III
中科院分区：
文献类型：
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作者：
Feeney, Matthew J.;Thomas, Samuel W., III
在水性介质中，当暴露于可见光时，从阳离子质子化部花青（MCH+）到螺吡喃（SP）可以发生负光致变色。在这里，我们展示了独特的简单的方式，其中聚合物可以通过共聚物制备来调整这些光致变色剂的关键特性。九种水溶性含SP聚合物产生宽范围的关键特性，负光致变色可访问MCH + pK（a）值跨越5个pH单位，光化学闭环的量子产率高达0.2，热平衡速率范围为2个数量级。在缓冲溶液中，这些聚合物中的许多显示出光稳定状态，其中大于80%的转化为SP，并且在15个循环中没有可检测到的光致变色疲劳。这些结果证明了通过螺吡喃侧基本身和水增溶性共聚单体来调节MCH+光致变色剂的关键性质的潜力。MCH + pK（a）对共聚单体结构的依赖性使得能够使用单一螺吡喃衍生物调节可逆光酸活性的pH范围，进一步展示了水溶性光致变色聚合物的多功能性。
In aqueous media, negative photochromism can occur from cationic, protonated merocyanines (MCH+) to spiropyrans (SP) upon exposure to visible light. Herein, we demonstrate the uniquely simple manner in which polymers can tune the key properties of these photochromes through copolymer preparation. Nine water-soluble, SP-containing polymers yield wide ranges of key properties for negative photochromism-accessible MCH+ pK(a) values spanning 5 pH units, quantum yields of photochemical ring closure up to 0.2, and rates of thermal equilibration ranging 2 orders of magnitude. In buffered solutions, many of these polymers showed photostationary states with greater than 80% conversion to SP and no detectable photochromic fatigue over 15 cycles. These results demonstrate the potential for tuning key properties of the MCH+ photochrome through both the spiropyran pendants themselves and the water-solubilizing comonomers. The dependence of MCH+ pK(a) on comonomer structure enabled tunable range of pH for reversible photoacid activity using a single spiropyran derivative, further showcasing the versatility of water-soluble photochromic polymers.