Switching Properties of a Spiropyran–Cucurbit[7]uril Supramolecular Assembly: Usefulness of the Anchor Approach |
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| Authors: | Jesper R Nilsson Cátia Parente Carvalho Dr Shiming Li Dr José Paulo Da Silva Prof Joakim Andréasson Dr Uwe Pischel |
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| Institution: | 1. Department of Chemical and Biological Engineering, Physical Chemistry, Chalmers University of Technology, 41296 G?teborg (Sweden), Fax: (+46)?31?772?38?58;2. Center for Research in Sustainable Chemistry and Department of Chemical Engineering, Physical Chemistry and Organic Chemistry, University of Huelva, Campus de El Carmen s/n, 21071 Huelva (Spain), Fax: (+34)?959?21?99?83;3. Faculty of Science and Technology, University of Algarve, Campus de Gambelas, 8005‐139 Faro (Portugal) |
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| Abstract: | A nitrospiropyran, which was modified with a cadaverine‐derived anchor, was investigated with respect to its thermally induced isomerizations, hydrolytic stability of the merocyanine form, and photochromic ring closure. The host–guest complexation of the anchor by the cucurbit7]uril macrocycle, evidenced by absorption titration, NMR spectroscopy, and electrospray ionization mass spectrometry, produced significant improvements of the switching properties of the photochrome: 1) appearance of the merocyanine form about 70 times faster, 2) practically unlimited hydrolytic stability of the merocyanine (two and a half days without any measureable decay), and 3) fast, clean, and fatigue‐resistant photoinduced ring closure back to the spiro form. The importance of an adequate molecular design of the anchor was demonstrated by including control experiments with spiropyrans with a shorter linker or without such structural asset. |
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| Keywords: | acidochromism cucurbiturils host– guest chemistry hydrolysis photochromism |
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