Dynamic platinum(II)- based metallosupramolecular architectures
Pike, Sarah Jane
Over the past two decades, transitions metals have been extensively employed towards the construction (using coordination driven assembly) and operation (using reversible metal-ligand switching motifs) of supramolecular architectures. This Thesis details the investigation of an array of dynamic platinum(II)-based metallosupramolecular architectures and includes a series of model studies on switchable platinum(II) coordination modes. Chapter Two describes the synthesis and study of a series of prototype noninterlocked molecular machines. The inherent dynamics of intramolecular metalligand substitution reactions (metallotrophic shifts) are exploited to drive a d8 platinum(II-)-phenanthroline component along different ligating architectures to achieve translational (and in one case rotary) motion of the sub-molecular components. Variable temperature NMR studies of these complexes have established the kinetic parameters for the observed shuttling processes. In Chapter Three, the switchable behaviour of a metal-ligand coordination motif is reported in which a proton input is employed to modify the overall thermodynamic bias and light is orthogonally utilized to selectively lower the energetic barrier for the binding event to re-equilibration. A discussion of the light-promoted ligand exchange reaction is presented, supported by a combination of TD-DFT calculations and kinetic studies. Chapter Four describes the exploitation of this discovered pH-switchable metalligand motif for the stimuli-responsive reversible assembly of two dimensional and three dimensional metallosupramolecular architectures. Whilst Chapter Five details how this reversible motif can be exploited to induce controlled exchange between “3+1” and “2+2” square planar platinum donor sets in response to the application of acid-base stimuli.