It has been reported that the intrinsic open-shell quinone radical electronic ground state is commonly present in classic narrow bandgap donor-acceptor organic semiconductors. Among them, aromatic inorganic acid radicals are one of the important categories of classical narrow bandgap donor-acceptor type organic semiconductors and display unique physical properties and electronic ground states. Generally, the conjugated planes play a crucial role in stabilizing multi-radical electronic systems. In this paper, we are the first to design, synthesize, and report fully planar graphene-like two-dimensional aromatic oxalic acid radical IDF-O8 based on the aromatic inorganic acid radical system, and study the physical properties of this aromatic high spin pan. In this graphene-like structure, the electron-withdrawing group of ketones can effectively delocalize radical electrons and achieve stability. In addition to exhibiting strong spin signals, the temperature of IDF-O8 reached 147 °C in aggregated state under the irradiation of 808 nm (1.2 W cm-2). This work provides a novel planarized radical design strategy and has great potential in seawater desalination.

Open-shell radicals have received a lot of attention due to its potential applications in highly efficient photothermal conversion and therapy. However, it is challenging to enhance the chemical and photothermal stability of the open-shell structure. Herein, a stable open-shell poly(3,4-dioxythiophene) radical PTO2 was readily synthesized via simple BBr3-demethylation of the copolymer P(TOMe2-EDOT) precursor using low-cost materials. The open-shell character of PTO2 was confirmed by the highly enhanced electron spin resonance signal comparing with P(TOMe2-EDOT). Interestingly, the powder of PTO2 exhibit extremely wide absorption range between 300 and 2500 nm, which is comparable with those of graphene and Fe3O4. Under the same irradiation of 1.2 W cm-2, the powder of PTO2 can reach 242 ℃ which is much higher 200 ℃ of the P(TOMe2-EDOT). The decreased photothermal conversion capability of the metal-ionized PTO2 complexes indicates that the radical structure of the polymer has a significant effect on the photothermal conversion properties. To date, PTO2 stands as one of the low cost pure organic photothermal materials with super-high photothermal conversion performances.