Thymine-covalently decorated, AIEE-type conjugated polymer as fluorescence turn-on probe for aqueous Hg2+

• A type of thymine-covalently decorated conjugated polymer (P3) was synthesized.
• P3 displays aggregation-induced emission enhancement (AIEE) feature.
• Fluorescence of P3 increased significantly with the presence of Hg2+.
• Detection limit of ∼15.3 nM for Hg2+ can be obtained by P3.
• P3 possess good selectivity, sensitivity and anti-interference toward Hg2+.

A type of thymine (T)-covalently decorated conjugated polymer (P3) with the feature of aggregation-induced emission enhancement (AIEE) was successfully synthesized via Cu-catalyzed click reaction between the acetylene-substituted precursor polymer (P2) and 3′-azido-3′-deoxythymidine. Chemical structures of target polymers were verified by FT-IR and 1H NMR analyses. With the introduction of aqueous Hg2+, fluorescence of P3 in THF–water mixture (VTHF/Vwater = 7/3) (buffered with 5 mM citric acid–disodium hydrogen phosphate, pH = 7.4) displayed gradual enhancement. The AIEE effect was activated by the formation of intermolecular aggregates, which was induced by the formation of T–Hg–T complex between polymer chains. Other common metal ions brought very slight interference for P3's response of Hg2+, and the detection limit of Hg2+ reached ∼15.3 nM for such probing system.