The synthesis of two 3D flexible covalent organic frameworks via Schiff base reactions for fluorescence sensing to nitroaromatic compounds and uptaking iodine

Yun-Long Gui; Heng Xu; Tong-Mou Geng; You-Shen Liu

doi:10.1016/j.saa.2025.126594

The synthesis of two 3D flexible covalent organic frameworks via Schiff base reactions for fluorescence sensing to nitroaromatic compounds and uptaking iodine

Spectrochim Acta A Mol Biomol Spectrosc. 2025 Jun 20:343:126594. doi: 10.1016/j.saa.2025.126594. Online ahead of print.

Authors

Yun-Long Gui¹, Heng Xu², Tong-Mou Geng³, You-Shen Liu¹

Affiliations

¹ Anhui Province Key Laboratory of Optoelectronic and Magnetism Functional Materials; Ultra High Molecular Weight Polyethylene Fiber Engineering Research Center of Anhui Province; School of Chemistry and Chemical Engineering, Anqing Normal University, Anqing 246011, China.
² Anhui Province Key Laboratory of Optoelectronic and Magnetism Functional Materials; Ultra High Molecular Weight Polyethylene Fiber Engineering Research Center of Anhui Province; School of Chemistry and Chemical Engineering, Anqing Normal University, Anqing 246011, China. Electronic address: xuheng@aqnu.edu.cn.
³ Anhui Province Key Laboratory of Optoelectronic and Magnetism Functional Materials; Ultra High Molecular Weight Polyethylene Fiber Engineering Research Center of Anhui Province; School of Chemistry and Chemical Engineering, Anqing Normal University, Anqing 246011, China. Electronic address: 2318052317@qq.com.

PMID: 40591981
DOI: 10.1016/j.saa.2025.126594

Abstract

The extensive use of nitroaromatic compounds (NACs) and the release of radioactive iodine can bring about infinite harm to human health and the ecological environment. Therefore, the efficient detection of NACs, uptake and sequestration radioactive iodine efficiently has become the focus of attention. In this paper, we introduced two flexible three-dimensional covalent organic frameworks (flexible 3D COFs), namely HTAEA and HTMB, which can be used for efficient fluorescence sensing of 2,4-dinitrophenol (DNP) and p-nitrophenol (p-NP), as well as reversible absorption of iodine. HTAEA and HTMB possess good thermal and chemical stability, with high BET-specific surface areas of severally 937 and 1214 m² g^-1. Both HTAEA and HTMB show excellent sensitivity, in especial, HTAEA has high selectivity and sensitivity for DNP with quenching constant (Ksv) of 3.26 × 10⁴ L mol^-1. The quenching principles result from both photoinduced electron transfer (PET) and Forster resonance energy transfer (FRET) processes. Both HTAEA and HTMB exhibit high iodine capture capabilities, reaching up to 3.51 and 3.42 g g^-1, respectively, which is attributed to the electron transfer from the flexible 3D COFs to the I₂, forming the polyiodide anionic complexes. HTAEA demonstrates higher sensitivity and selectivity than HTMB in fluorescence sensing DNP and in iodine adsorption amount and rate of adsorption.

Keywords: Covalent organic frameworks; Flexible; Fluorescence sensing; Iodine capture; Nitroaromatic compounds.