First Observation of Alkali Metal Ion Induced Trans-Cis Isomerization of Palladium(II) Phosphane Complexes Containing Crown Ether Moieties

摘要

There has been growing interest in the design of allosteric host molecules that can efficiently transmit the information associated with the binding of an ion or molecule to another binding site through structural changes induced on binding. Such allosteric binding behavior not only serves as a means to control the binding or release of ions or molecules, but also provides a new strategy for the design and construction of molecular-switching devices. Although trans-cis thermal and photoisomerization reactions are well-known and numerous works on photoinduced ion binding have appeared in the literature, there have been no reports of metal-ion-induced or -assisted isomerization reactions brought about by allosteric interactions. In this regard, we were interested in investigating the possibility of using metal-ion complexation and allosteric interactions to induce isomerization processes. Herein, we report the unprecedented trans-cis isomerization of dichloropalladium(II) phosphanylcrown complexes that is induced by the binding of alkali-metal ions, as evidenced by UV/Vis, ~1H NMR, and ~(31)P NMR spectroscopy as well as ESI-MS, and represents a novel type of allosteric host that is the first of its kind.