Robust Self‐Assembled Monolayers of Ru^II and Os^II Polypyridines on Gold Surfaces: Exploring New Potentials

Abstract

ABSTRACT:Metal complexes [M(phtpy)(pztpy)](PF 6 ) 2 (phtpy = 4'-phenyl-2,2':6',2"-terpyridine, pztpy = 4'-(Npiperazinyl)-2,2':6',2"-terpyridine, M = Ru, Os) were prepared and examined spectroscopically and electrochemically. The piperazine attachment was found to significantly modify the photophysical and electrochemical properties compared to the parent bis-terpyridine complexes, causing a red-shift of the 1 MLCT (23 nm) and a substantial cathodic shift of the redox potential (0.30 V for Ru, 0.23 V for Os). Self-assembled monolayers (SAMs) of the complexes on polished gold electrodes were generated simply via the in situ formation of a dithiocarbamate (DTC) anchoring group at the terminal piperazinyl nitrogen on the pztpy ligand. Cyclic voltammetry revealed that the monolayers show excellent reversible behaviour and exceptional stability. The high stability of the SAMs is attributed to the strong bidentate attachment to the gold surface of the DTC tether and the favourable low oxidation potentials of the complexes which result from the electron-rich piperazine nitrogen on the pztpy ligand. Such DTC-based SAMs demonstrate a substantial improvement over commonly-employed thiol-based systems, and offer new scope for future development.

Terpyridine‐Functionalized Surfaces: Redox‐Active, Switchable, and Electroactive Nanoarchitecturesgland

“…Very robust SAMs of Ru II or Os II bis-terpyridine complexes on polished gold electrodes were reported by Murphy et al [ 46 ] The heteroleptic piperazine-functionalized complexes 13 assembled onto the surface by the in situ formation of a dithiocarbamate (DTC) anchoring group at the terminal piperazine N -atom by reaction with CS 2 ( Figure 11 a,b). An average surface coverage of 5.5 mol cm − 2 was calculated from CV data.…”

Highly Efficient Triplet Photosensitizers: A Systematic Approach to the Application of IrIII Complexes containing Extended Phenanthrolines

“…Transitionm etal complexes as triplet-photosensitizingm aterials have potential applications in photovoltaics, [1][2][3][4] photocatalysis, [5][6][7][8] andu pconversion. [9][10][11][12][13][14][15][16] It is generally accepted that for triplet-sensitizing applications,t ransition metal complexes need to absorb stronglyi nt he visible region and to exhibit long-livedtriplet states.U nfortunately,d espite some exceptions, [14,16,17] transition-metal complexes with these properties are unusual.…”

Terpyridine-fused polyaromatic hydrocarbons generated via cyclodehydrogenation and used as ligands in Ru(ii) complexes

“…Terpy units have also been shown to be effective synthetic platforms on which to introduce dithiocarbamates as highly stable and robust anchoring units for attachment to Au surfaces. 18 In our Ru(II) complexes, surface self-assembly would be driven by π-stacking interactions between the HBC-fused aromatic platforms, providing uniform surface coverage. The inherent hydrophobicity of the PAH segment would also decrease the probability of water-induced dye degradation in any Ru(II)-dye thin film.…”