Photoswitchable π‐Extended Dithienylethenes with an Attached Molecular Recognition Site

Photoswitchable dithienylethenes have been extended in positions 5 and 5′ with π‐systems resulting in absorptions of light with longer wavelengths when electrocyclization and ‐reversion are carried out. The extended π‐systems also improve conductivities potentially. cis‐Orientation of the thienyl rings was accomplished by integrating the central double bond into maleic imides. The nitrogen atoms of the imides were substituted by a Hamilton receptor allowing supramolecular binding of complementary guests such as barbiturates. Both, a stiff and a flexible connection between photoswitch and receptor was realized. The resulting photoswitches showed reversible switching over several cycles and were able to bind diethyl barbiturate with binding constants of > 104 m–1. A photoswitchable diarylethene was connected to a Hamilton receptor to allow supramolecular binding to respectively modified surfaces or dendrimers. The switches are substituted with extended π‐systems to allow long wavelength absorptions and improved conductivities. The connection between the photoswitch and the binding site is either stiff (direct connection) or flexible (butyloxy).