Selective Photothermal Catalysis Enabled by Molecular Recognition on Ligand-Protected Gold Nanoparticles

The photothermal effect, which converts light into heat using nanosized light absorbers, has emerged as a powerful tool in energy conversion, cancer therapy and chemical transformation. Even if still debated, localized heating around nanoabsorbers under low-intensity irradiation, conjugated with the molecular recognition abilities of monolayer protected nanoparticles, could enable the design of selective photothermal catalysts. Here, we report the development and application of thermolabile self-cleaving molecular probes based on N-benzyl-N-(2-pyridyl)-aminoethanol esters and carbonates to investigate localized photothermal effects. A series of derivatives with systematically varied substituents were synthesized and characterized, revealing that thermal reactivity can be finely tuned through electronic effects and solvent composition. Using fluorescence spectroscopy to monitor probe cleavage, we demonstrate that low-intensity light irradiation (525 nm) induces reaction rates consistent with local temperature increases of 10°C-15°C above the bulk temperature. Crucially, the rate acceleration is observed only when the probes bind to the nanoparticle coating monolayer, as governed by electrostatic interactions. These results provide direct evidence for selective photothermal catalysis driven by molecular recognition, opening new perspectives for the design of smart photothermal nanozymes.