Proton uptake vs. redox driven release from metal–organic-frameworks: Alizarin red S reactivity in UMCM-1

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Switzerland), 2013, Vol.689 (15), p.168-175
• Main Authors: Halls, Jonathan E., Ahn, Sunyhik D., Jiang, Dongmei, Keenan, Luke L., Burrows, Andrew D., Marken, Frank
• Format: Article
• Language: English
• Subjects: acetonitrile; alizarin; Alizarin red S; Electrocatalysis; electrochemistry; electrolytes; Electron transfer; Mediator; Metal–organic framework; Release; Solvent; Voltammetry
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/j.jelechem.2012.11.016

[Display omitted] ► Redox activity of alizarin red S in metal-organic framework pores. ► Host degradation with associated expulsion of alizarin red S. ► Buffer effects on “pore redox processes”. Small redox active molecules such as alizarin red S are readily adsorbed and bound into redox-inactive metal–organic framework hosts such as UMCM-1. Redox activity of the bound guest molecule is of interest for electrochemical conversions and electrocatalysis within pores. For the reduction of alizarin red S charge compensating proton uptake into pores is expected. However, it is shown here that alizarin red S redox processes in UMCM-1 immersed in aqueous electrolyte, ethanolic electrolyte, and in acetonitrile electrolyte media are dominated instead by surface processes and the potential driven reductive release of leuco-alizarin red S into the surrounding solution. Self-mediation via released alizarin red S occurs, whereas in acetonitrile a cobaltocene redox mediator is employed for the potential driven redox release of alizarin red S from the UMCM-1 host lattice.