Investigation of the photothermal properties of a large series of Metal-Bis(Dithiolene) complexes: Impact of the molecular structure and ranking using the photothermal index IPT

The photothermal properties in the NIR region of a large series of 19 metal-bis(dithiolene) complexes and of a perylene derivative have been studied in detail. Photophysical and thermal measurements were repeated several times to obtain good uncertainties on molar extinction coefficients, temperature increases and photothermal efficiencies. This large series of metal-bis(dithiolene) complexes enabled us to assess the impact of the nature of the metal center, the nature of the ligand and the number and length of the carbon chains on absorption properties and photothermal efficiencies. Thanks to these reliable data, the recently introduced photothermal index IPT, which combines molar absorptivity ε and photothermal efficiency η, has also been effectively used to rank all these molecular photothermal agents according to their photothermal activity. This work confirms that the photothermal index IPT can be used effectively to rank photothermal agents according to their ability to convert light into heat.