The paper "Intrinsic proton conduction in 2D sulfonated covalent organic frameworks through a post-synthetic strategy" by Associate Professor Yuki Nagao (Materials Chemistry Area), Dr. LI, Zhongping (graduated from the JAIST PhD course at September 2019 in Nagao Lab, Researcher), Ms. LIU, Zhaohan (2nd-year master's student in Nagao Lab), Mr. YAO, Yuze (2nd-year doctoral student in Nagao Lab), Mr. HASAN, Md. Mahmudul (3rd-year doctoral student in Nagao Lab) and collaborators published in CrystEngComm was selected as Hot Articles (Top 10% Articles Recommended by Reviewers).

■Date of selection
October 6, 2021

■Title
Intrinsic proton conduction in 2D sulfonated covalent organic frameworks through a post-synthetic strategy

■Authors
Yuwei Zhang, Chunzhi Li, Zhaohan Liu, Yuze Yao, Md. Mahmudul Hasan, Qianyu Liu, Jieqiong Wan, Zhongping Li*, He Li* and Yuki Nagao*（* Corresponding authors）

■Abstract
Two-dimensional covalent organic frameworks (2D COFs) have attracted much attention in proton conduction, owing to their regular pore channels and easy functionalization. However, most of the COFs required loading of proton carriers to achieve high proton conductivity. Here, we report the immobilization of flexible sulfonic acid groups on the channel walls of PyTTA-DHTA-COF (synthesized by condensation of 4,4′,4′′,4′′′-(pyrene-1,3,6,8-tetrayl)tetraaniline and 2,5-dihydroxyterephthalaldehyde) via a simple post-synthetic modification strategy. The sulfonated COF showed intrinsic proton conductivity up to 10⁻³ at 25 °C and 100% relative humidity (RH) and high conductivity up to 10⁻² S cm⁻¹ at 70 °C and 100% RH without the introduction of any non-covalent acid molecules or imidazole derivatives.

■Comment
It is a great honor for us to be selected as the Hot Article at CrystEngComm. I would like to gratitude to Prof. Yuki Nagao, Dr. He Li, and all our lab members for contributions and support to this work. I also appreciate the support by JSPS. We believe that this research is a step towards achieving our research goals and inspiring us to do better in the future.

November 4, 2021