Photophysical and Electrochemical Study of New Luminescent and Redox-Active Tetrazine Derivatives Grafted on Gold Nanoparticles

New tetrazine derivatives able to be grafted on gold surfaces have been synthesized with either disulfide or thioctic anchoring units, and their electrochemical and photophysical properties are investigated in solution. In parallel, gold nanoparticles have been electrodeposited on indium tin oxide surfaces and then functionalized by the tetrazine compounds. The modified surfaces have been characterized by X-ray photoelectron spectroscopy with a focus on the influence of the deposition potential and immersion time. Tetrazines remain fully electroactive and emissive once grafted. Electrochemical characterization shows that monolayers of tetrazine are formed with high values of the electron transfer rate with the thioctic anchoring group. The photophysical study allows us to estimate the optimal deposition time and shows a gradual bleaching under continuous excitation with a rate depending on the excitation power. The monolayers grafted through the thioctic unit show the best performances from the electrochemical and photophysical point of view, suggesting a better organization than with the disulfide unit.