Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
J Am Chem Soc. 2012 Dec 12;134(49):20146-50. doi: 10.1021/ja3091033. Epub 2012 Nov 29.
A new water-soluble thermoresponsive pillar[6]arene with triethylene oxide groups was synthesized. The pillar[6]arene showed lower critical solution temperature behavior in aqueous solution. Its clouding point was photoreversibly switched based on a photoresponsive host-guest system. The trans form of an azobenzene guest formed a stable 1:1 complex with the pillar[6]arene. Complexation increased the clouding point. Irradiation with UV light induced a conformation change for the azobenzene guest from the trans to cis form, and dethreading occurred because of a size mismatch between the cis form and the pillar[6]arene cavity. This dethreading decreased the clouding point. The photoresponsive host-guest system was reversible, and the clouding point could be switched by alternating irradiation with UV or visible light. We demonstrated photoresponsive reversible clear-to-turbid and turbid-to-clear transitions for the solution based on the reversible switching of the clouding point using the photosensitive host-guest system.
一种新的水溶性温敏性杯[6]芳烃，带有三乙二醇基团，被合成出来。该杯[6]芳烃在水溶液中表现出较低的临界溶液温度行为。其浊点可以基于光响应主客体体系进行光可逆切换。作为客体的偶氮苯在转变为顺式构象后，与杯[6]芳烃形成了稳定的 1:1 配合物。这种复合物增加了浊点。用紫外线照射会诱导偶氮苯客体从反式构象转变为顺式构象，由于顺式构象与杯[6]芳烃空腔之间的尺寸不匹配，发生了脱螺纹现象。这种脱螺纹降低了浊点。光响应主客体体系是可逆的，通过交替用紫外线或可见光照射可以实现浊点的切换。我们利用光响应主客体体系可逆切换浊点的能力，展示了基于该体系的溶液的光响应性可逆澄清-变浑和变浑-澄清转变。
