Multifunctional Cyanido Bridged Coordination Framework Materials Incorporating Ruthenium

Abstract

The past decade has seen remarkable growth in the field of coordination frameworks owing to their enormous structural and chemical diversity. The vast majority of frameworks reported in the literature have consisted of transition metal ions of the first-row (e.g., Fe2+, Co2+, Ni2+ Cu2+ or Zn2+), while examples of frameworks containing second-row transition metals are extremely rare owing to their relative inertness to ligand substitution. This thesis reports research on ruthenium based cyanido bridged coordination frameworks. Ruthenium metal clusters and complexes are well characterised optically, magnetically and electronically, and these structural building units (SBUs) when incorporated into known porous MOF topologies can embue added multifunctional properties including embedded photophysical and redox characteristics of ruthenium-based complexes, including the longevity of their excited states and their inertness in a variety of oxidation states. Chapter 3 reports the first investigation of the electronic and optical properties of the series [(RuII,III2(O2CMe)4)3MIII(CN)6] , where M = Cr (1), Co (2) and Fe (3), with particular attention on newly synthesised analogues incorporating the second- and third-row transition metals RuIII and IrIII. The solid state electrochemical and optical properties of the new 3D frameworks [(RuII,III2(O2CMe)4)3RuIII(CN)6] (4) and [(RuII,III2(O2CMe)4)3IrIII(CN)6] (5) were interrogated and compared with their analogs based on the first-row elements. Chapter 4 investigates the family of materials with general formula [(RuII,III2(O2CMe)4)3MIII(CN)6] for M = Cr, Fe, Co, Ru, Ir, which exhibits low isotropic positive thermal expansion (PTE). Detailed Rietveld analysis reveals how interpenetration causes a dampening of the low energy lattice modes and reduces the vibrational flexibility of the cyanido bridge. Chapter 5 focuses on the discovery of a previously unobserved Prussian Blue structural analogue, a tetragonal non-vacancy pillared Hofmann-type structure CuII2[FeII(CN)6] and CuII2[RuII(CN)6]; and a study of a range of negative thermal expansion (NTE), ZTE and PTE in these two new materials as well as a family of six related cubic Prussian Blue-type frameworks MII2[FeII(CN)6] and MII2[RuII(CN)6] for M = Fe, Co, Ni.