Successful Bifunctional Photoswitching and Electronic Communication of Two Platinum(II) Acetylide Bridged Dithienylethenes

Coordinating two dithienylethenes to a platinum center results in the reversible ring closure of both photochromic units in a model for a photoresponsive π-conjugated polymer. This system demonstrates how metal-sensitized photochemistry, from a triplet excited state, circumvents the problems associated with other multicomponent photochromic systems, where significant electronic interactions in the ground state and singlet excited state prevent full photoswitching. Changes in charge-transfer behavior based upon conversion of both dithienylethenes to their ring-closed forms illustrate how photomodulation of conductivity through a conjugated polymer might be achieved using Pt-bis(acetylide)s.