Probing frontier orbital energies of (Co9(P2W15)3) polyoxometalate clusters at molecule-metal and molecule-water interfaces

TL;DR

This study investigates the frontier orbital energies of Co9(P2W15)3 polyoxometalate clusters at interfaces, revealing their potential for charge transport applications through surface characterization and electrochemical analysis.

Contribution

It introduces a method to probe the frontier orbital energies of polyoxometalates at interfaces, combining surface assembly with electrochemical and microscopy techniques.

Findings

Frontier orbital energies correlate with cyclic voltammetry data.

Self-assembled monolayers enable charge transport studies.

Polyoxometalates maintain properties at molecule-metal interfaces.

Abstract

Functionalization of polyoxotungstates with organoarsonate co-ligands enabling surface decoration was explored for the triangular cluster architectures of the composition [CoII9(H2O)6(OH)3(p-RC6H4AsVO3)2({\alpha}-PV2WVI15O56)3]25-({Co9(P2W15)3}, R = H or NH2), isolated as Na25[Co9(OH)3(H2O)6(C6H5AsO3)2(P2W15O56)3]86H2O (Na-1) and Na25[Co9(OH)3(H2O)6(H2NC6H4AsO3)2(P2W15O56)3]86H2O (Na-2). The axially oriented para-aminophenyl groups in 2 facilitate the formation of self-assembled monolayers on gold surfaces, and thus provide a viable molecular platform for charge transport studies of magnetically functionalized polyoxometalates. The title systems were isolated and characterized in the solid state and in aqueous solutions, and on metal surfaces. Using conducting tip atomic force microscopy (C-AFM), the energies of {Co9(P2W15)3} frontier molecular orbitals in the surface-bound state were found to directly correlate with cyclic voltammetry data in aqueous solution.