| Abstract: | It remains highly challenging to identify small molecule‐based photothermal agents with a high photothermal conversion efficiency (PTCE). Herein, we adopt a double bond‐based molecular motor concept to develop a new class of small photothermal agents to break the current design bottleneck. As the double‐bond is twisted by strong twisted intramolecular charge transfer (TICT) upon irradiation, the excited agents can deactivate non‐radiatively through the conical intersection (CI) of internal conversion, which is called photoinduced nonadiabatic decay. Such agents possess a high PTCE of 90.0 %, facilitating low‐temperature photothermal therapy in the presence of a heat shock protein 70 inhibitor. In addition, the behavior and mechanism of NIR laser‐triggered molecular motions for generating heat through the CI pathway have been further understood through theoretical and experimental evidence, providing a design principle for highly efficient photothermal and photoacoustic agents. |
