A cyanide-responsive supramolecular nanovalve based on Pd(ii)-templated pseudo-rotaxane†
We report here the design and synthesis of a nanovalve system consisting of a carrier based on mesoporous silica nanoparticles and mechanized with a square planar Pd(II)-templated pseudo-rotaxane. This nanovalve was responsive to demetalation by cyanide anions, followed by the concomitant release of both the macrocycles and the contents of the pores, in this instance dye indicators. Gate-keeping of the mesopores was achieved by the formation of an intact coordination between the monodentate pyridine axles soluble in aqueous solution and the tridentate macrocycle Pd complex via a square planar metal template approach. A facile nanovalve system responsive to an anionic stimulus was therefore developed. Luminescence spectrometry was successfully used to demonstrate that the anion-stimulated dye release from the nanovalves gated by the Pd(II) metal template was independent of pH.