Multifunctional switching properties of "wire-like" dinuclear ruthenium bis-alkynyl spiropyran complexes

Multifunctional switches are crucial to the development of smart molecular materials and molecular-electronic applications. Here, we describe the synthesis, structure, and characterization of several spiropyrans functionalized with alkynyl-[Ru(dppe)(2)] moieties. Through electrochemical and spectroelectrochemical studies, we demonstrate access to several stable redox states, in addition to states accessed via acidochromism and photoisomerisation. Initial protonation was found to occur at the alkynyl functionality followed by acid-induced ring-opening of the spiropyran ligand to form the protonated merocyanine. The protonated merocyanine can be switched from the Z- to E-isomer by using ultraviolet light. The spiropyran was also shown to be an effective insulator for electronic communication across the molecular backbone.