A New Squaraine‐Linked Triazinyl‐Based Covalent Organic Frameworks: Preparation, Characterization and Application for Sensitive and Selective Determination of Fe 3+ Cations

A new triazinyl‐based covalent organic frameworks(COFs) linked by squaraine(ST‐COF‐1) was synthesized via condensation of squaric acid (SA) and 1,3,5‐triazine‐2,4,6‐triamine (Melamine, MA). The BET surface area of ST‐COF‐1 was calculated as 484.12 m 2 g −1 . The suspension of this material will emit strong blue fluorescence under the irradiation of 365 nm ultraviolet lamp. Strong quenching effects of Fe 3+ on the fluorescence of the COFs allowed selective chemosensing for Fe 3+ cation. In addition, some nitro aromatic compounds also cause strong fluorescence quenching, which proves that this material can also be used for the qualitative detection of nitro aromatic compounds.