Diketopyrrolopyrrole-based covalent organic polymer with donor-acceptor structure for efficient near-infrared photothermal conversion

Efficient near-infrared (NIR) organic photothermal agents are crucial for the effective ablation of cancer cells; however, their synthesis, high performance, and stability remain challenging. In this work, we report the design and synthesis of a covalent organic polymer (COP), TPDA-DPP-COP, constructed through an optimized Schiff-base condensation between tetra(4-aminophenyl) diamine (TPDA) as the electron donor and diketopyrrolopyrrole (DPP) as the electron acceptor, respectively. The morphology, microscopic structure, optical properties, and donor–acceptor (D–A) conjugation effects of TPDA-DPP-COP were systematically investigated using experimental characterizations and theoretical calculations. Benefiting from its extended conjugation and red-shifted absorption, TPDA-DPP-COP exhibited an outstanding NIR photothermal conversion efficiency of 70.2 % in tetrahydrofuran (THF), reaching a maximum temperature of 43.2 °C within 5 min under 808 nm laser irradiation at 0.5 W/cm². This study provides a promising strategy for the development of efficient and stable NIR photothermal materials for future biomedical applications.