Cover Picture: Photocontrolled Release and Uptake of a Porphyrin Guest by Dithienylethene-Tethered β-Cyclodextrin Host Dimers (Chem. Eur. J. 5/2004)

✍ Scribed by Alart Mulder; Amela Juković; Fijs W. B. van Leeuwen; Huub Kooijman; Anthony L. Spek; Jurriaan Huskens; David. N. Reinhoudt

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 24 KB
• Volume: 10
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/chem.200490013

✦ Synopsis

The cover picture shows the reversible photocontrolled release and uptake of a tetrasulfonatophenyl porphyrin (TSPP) from a photoswitchable dithienylethene‐tethered β‐cyclodextrin dimer. The background displays the interplay of the two elements involved: light and water. The open flexible form of the dimer binds TSPP strongly in aqueous solution (orange structure). Irradiation of the complex with UV‐light (blue arrow) closes the dithienylethene tether of the β‐cyclodextrin dimer and hence places the two β‐cyclodextrin cavities further apart from each other (blue structure, top). The stability of this closed dimer–TSPP complex is significantly lower and TSPP is released from the dimer to the aqueous solution (blue structure, right). By irradiation with visible light (orange arrow) the dithienylethene tether can be completely converted back to the more flexible open form, allowing the dimer to once again strongly bind TSPP and leading to the uptake of TSPP from aqueous solution. This chemistry is described in more detail by J. Huskens, D. N. Reinhoudt, et al. on p. 1114ff.