Exploration of mass transport and heterogenous electron transfer in cobalt redox polyether hybrids

Chapter One sets the stage for this thesis research by describing the impetus behind development and study of oligomer-tailed bypridine metal salt complexes known as redox polyether hybrids. Chapter Two confirms the validity of electrochemical measurements (heterogenous electron transfer rate constants, ko, and physical diffusion coefficients, D _PHYS) in the most rigid of these complexes, as preliminary studies established new lower boundaries for these measurements. This chapter also lays the foundation from which the subsequent chapters can present intriguing observations pertaining to the dynamics of mass transport and electron transfer in these melts.; Chapter Three inspects the anomalous diffusion behavior observed for a series of redox polyether hybrids. This behavior is attributed to “molecule-scale diffusion”: on the timescale of the electrolysis, the diffusion length of the melt complex ranges from multiples to fractions of the physical dimension of the diffusant itself. This chapter also examines the relation, via classical diffusional theory, between the rates of diffusional hops and electron transfers.; In Chapter Four, the first electrochemical investigation of net mass transport through the glass transition, T_g, is presented. Further insight into the modes of mass transport in redox polyether hybrids is offered, as physical diffusion and ionic conductivity show distinct behaviors through T_g.; Chapter Five reports ko and D_PHYS values, both multiple-temperature and isothermal, for a series of redox polyether hybrids. The activation energy barriers are reported and discussed. The intercepts of these plots are used to establish the adiabaticity of the reaction. In addition, analysis of available ionic conductivity data allows discussion of previously-unreported counterion diffusivity, D_ClO4, and its correlation with ko. This discussion adds support to the observations in Chapter Four indicating the decoupling of D_PHYS from D _ClO4.