A NIR‐II Fluorescent Probe for Hydrogen Sulfide Detection Based on Blocking Intramolecular Charge Transfer

Abstract A NIR‐II fluorescent probe (Et‐1080) for H 2 S detection was fabricated based on the intramolecular charge transfer blocking mechanism. The enhanced electron density of the indole donor further drove the Et‐1080′s absorption and emission to the NIR‐II region with a high molar absorption coefficient and acceptable fluorescence quantum yield. The C=N double bond of electron‐deficient indole can react with H 2 S rapidly via a nucleophilic addition mechanism, resulting in the destruction of conjugated structure and fluorescence quenching of the Et‐1080 molecule. The probe showed high selectivity and sensitivity to H 2 S, which could realize the rapid detection of H 2 S in NIR‐II band and showed great potential in the further disease diagnosis associated with H 2 S.