He Yonglin, Liao Hailiang, Lyu Shanzhi, Xu Xiao-Qi, Li Zhengke, McCulloch Iain, Yue Wan, Wang Yapei
Department of Chemistry, Renmin University of China Beijing 100872 China
State Key Laboratory of Optoelectronic Materials and Technologies, Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, Guangzhou Key Laboratory of Flexible Electronic Materials and Wearable Devices, School of Materials Science and Engineering, Sun Yat-Sen University Guangzhou 510275 China
Chem Sci. 2021 Feb 17;12(14):5177-5184. doi: 10.1039/d1sc00060h.
Great attention is being increasingly paid to photothermal conversion in the near-infrared (NIR)-II window (1000-1350 nm), where deeper tissue penetration is favored. To date, only a limited number of organic photothermal polymers and relevant theory have been exploited to direct the molecular design of polymers with highly efficient photothermal conversion, specifically in the NIR-II window. This work proposes a fused backbone structure locked an intramolecular hydrogen bonding interaction and double bond, which favors molecular planarity and rigidity in the ground state and molecular flexibility in the excited state. Following this proposal, a particular class of NIR-II photothermal polymers are prepared. Their remarkable photothermal conversion efficiency is in good agreement with our strategy of coupling polymeric rigidity and flexibility, which accounts for the improved light absorption on going from the ground state to the excited state and nonradiative emission on going from the excited state to the ground state. It is envisioned that such a concept of coupling polymeric rigidity and flexibility will offer great inspiration for developing NIR-II photothermal polymers with the use of other chromophores.
近红外（NIR）-II窗口（1000-1350nm）中的光热转换越来越受到广泛关注，该窗口有利于更深的组织穿透。迄今为止，仅开发了有限数量的有机光热聚合物及相关理论来指导具有高效光热转换的聚合物的分子设计，特别是在NIR-II窗口中。这项工作提出了一种稠合主链结构，其锁定了分子内氢键相互作用和双键，这有利于基态下的分子平面性和刚性以及激发态下的分子柔韧性。按照这一设想，制备了一类特定的NIR-II光热聚合物。它们卓越的光热转换效率与我们将聚合物刚性和柔韧性相结合的策略高度吻合，这解释了从基态到激发态时光吸收的改善以及从激发态到基态时的非辐射发射。可以预见，这种聚合物刚性和柔韧性相结合的概念将为利用其他发色团开发NIR-II光热聚合物提供巨大的启发。
