The Trans-Cis Isomerisation of Bis(dioxolene)bis(pyridine)Ruthenium Complexes

A career in phthalocyanine chemistry – the Linstead Award 2002

“…3d) [32,33] was instrumental in part for a subsequent extensive study of crown substituted phthalocyanines [34][35][36][37][38][39][40][41][42][43]. Dimerization of a cobalt crowned species was controlled by the presence of potassium ion leading to the possible use of this species as a sensor for potassium ions [32] or more generally as a gas sensor [35,[43][44][45][46].…”

“…3 , 7 ,8 ,1 2 , 13 , 17 , 18 -o ctak is ( N -meth yl-4 [127]. The tetracationic species (I), and its 2,3 analog, have proven to be quite versatile electrocatalysts sensing a wide range of different targets [32,98,118,[121][122][123][124][125][126] (Scheme 2). Two-electron redox processes are observed [32] but in the interest of brevity, we describe here similar two-electron redox behavior undertaken with the octacationic octapyridinium porphyrazine (II) described by Hoffman [127].…”

“…By far the majority of published work on the application of phthalocyanine modified electrodes to the detection of a wide range of target materials [75] have involved MPc electrocatalysts exhibiting only one-electron surface processes. The involvement of two-electron processes should lead to new electrocatalytic opportunities with these species and is under active study [32]. Figure 14 displays the Pourbaix diagram based on the data in Fig.…”

“…The key issue is that each surface can be ʻdialedʼ by appropriate choice of polarization potential and electrolyte pH, and each is a unique compound with its own chemistry, and its own electrocatalytic properties. For example, at pH 12, all the hydroxocobalt(I) species identified on the right hand side of the diagram are active catalysts for the reduction of hydrogen peroxide but the protonated species [Co I Pz{1+}H] 4+ (written in the figure as Co(I){1+}H) is inactive even though it would have the largest thermodynamic driving force for reduction; evidently the kinetic pathway is shut off [32,128]. The corresponding mesotetrakis(l-methylpyridinium-4-yl)porphinato)cobalt was studied in solution by Araullo-McAdams, and Kadish [129].…”