Fluorescent multi-component polymer sensors for the sensitive and selective detection of Hg2+/Hg+ ions via dual mode fluorescence and colorimetry

Abstract

Multi-component polymers (MCPs) incorporate multiple components into the main chain or pendant group and have special functions. In this work, the small-molecule fluorescent boron-dipyrromethene (BODIPY), with ester groups and/or alkoxyl long chains, was synthesized first. Then, this small-molecule BODIPY and the components containing CC bonds (HD and PD) were reacted via the Heck coupling reaction to obtain macromolecular probes that perform different functions. With the help of ester groups and alkoxyl “tail”, polymers MCP1 and MCP2 were soluble in a variety of water-miscible organic solvents. Moreover, MCP3 and MCP4 were completely soluble in water. These macromolecular probes showed sensitive and selective recognition toward Hg²⁺/Hg⁺ because of the introduced components (HD and PD) containing CC bonds. After binding to Hg²⁺/Hg⁺, MCP1 and MCP2 demonstrated fluorescence quenching and color changes, which allowed the dual-channel specific detection of Hg²⁺/Hg⁺. Compared with the probes containing HD, the probes containing PD showed higher sensitivity, and the good recognition ability caused the detection limit to be as low as 0.32 μM, which may be due to the “molecular wire” mechanism. The small-molecule components with different functional groups were polymerized into fluorescent polymer materials. This methodology endows the polymer probe with good solubility and high sensitivity, and the as-prepared polymers could sense metal ions in aqueous environments.