Ionic partition diagram of tetraphenylporphyrin at the water|1,2-dichloroethane interface

Abstract

a b s t r a c tFrom the thermodynamic data obtained by ion-transfer voltammetry, we derive here the ionic partition diagram of 5,10,15,20-tetraphenyl-21H,23H-porphine (H 2 TPP) at the water|1,2-dichloroethane interface using a simple Born solvation model. This zone diagram shows under which form this porphyrin is present, i.e. neutral, monoprotonated or diprotonated, and in which phase i.e. either in the aqueous or the organic phase as a function of the aqueous pH and the interface polarisation that can be controlled externally or by the distribution of supporting electrolytes. This diagram explains why the monoprotonated form has been difficult to observe when doing biphasic pH titrations.

Tetraoctylphosphonium Tetrakis(pentafluorophenyl)borate Room Temperature Ionic Liquid toward Enhanced Physicochemical Properties for Electrochemistry

“…This ion partitioning can be controlled through the application of a potential so that ions can be pushed or pulled across the interface. This facile principle has expanded, resulting in advances toward applications such as sensors, , ion selective membranes, metal extraction processes, − along with garnering an improved understanding of ion partitioning and aspects of fundamental electrochemistry. − …”

Catalysis of Oxygen Reduction by Metal-Free Porphyrins in One- and Two-Phase Liquid Systems

“…36 From the thermodynamic data obtained by ion transfer voltammetry, the ionic partition diagram of H 2 TPP in the water-1,2-DCE phase liquid system was derived using a simple Born solvation model. 100 This zone diagram indicates in which form this porphyrin is present, i.e., neutral, monoacid or diacid, and in which phase, i.e., either in the aqueous or the organic solvent phase, as a function of the aqueous pH, and the interfacial potential difference that can be controlled externally, or by the partition of a common ion. The diagram explains why the monoacid has been difficult to detect in the course of the biphasic pH titration.…”

“…The diagram explains why the monoacid has been difficult to detect in the course of the biphasic pH titration. 100 In further studies, 96,101 the effect of substitution on the phenyl ring of H 2 TPP on the acid-base behavior of the porphyrin free bases was investigated in relation to their catalytic capability toward the oxygen reduction by ferrocene derivatives at the polarized ITIES. In particular, cyclic voltammetry was used to evaluate acid dissociation constants for protonated 5-(p-aminophenyl)-10,15,20-tris(pentafluorophenyl)porphyrin (H 2 FAP), 96 5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin (H 2 TPPOCH 3 ) and 5,10,15,20-tetrakis(4-nitrophenyl)porphyrin (H 2 TPPNO 2 ).…”

“…19 Investigations of the metal-free porphyrin catalysts could be relevant to studies of the non-metal sites binding O 2 in biological enzyme-catalyzed oxidations. 20,21 100 Samec et al This chapter will review the major achievements in molecular catalysis of oxygen reduction by metal-free porphyrins in one and two-phase liquid systems. Chemical structures of the catalysts to be focused upon are depicted in Figure 1.…”

Ion transfer of weak acids across liquid|liquid interfaces

“…Therefore, the diagrams define the domains of predominance of each species either in the aqueous or in the organic phase, and they offer a global and direct visualisation of all the transfer mechanisms [1][2][3][4][5]7]. In recent years, a large number of ionisable drugs, such as acids, bases, ampholytes or zwitterionic species, have been characterized using these ionic partition diagrams, showing the usefulness of the methodology [18][19][20]22,26,[46][47][48][49][50][51]56,58,59,[63][64][65][66][67][68][69][70][71][72][73]. However, due to the assumptions involved in the model [19], these diagrams do not reproduce satisfactorily the boundary lines where two processes coexist.…”