A cross-linkable phthalonitrile derivative as a precursor to synthesize nitrogen-doped carbon nanodots for Ni ion detection

Abstract

The design of organic precursors with optimized molecular structures is of great importance for improving the fluorescent properties and sensing applications of heteroatom-doped carbon nanodots (CDs). Herein, we designed and synthesized a phthalonitrile derivative containing both melamine and benzoxazine moieties, which has been, for the first time, employed as a cross-linkable precursor to prepare nitrogen-doped carbon nanodots (N-CDs), showing fluorescence emission with a large Stokes shift. As a result of the good affinity between the surface functional groups of N-CD and Ni ions proven by XPS and FTIR techniques, the fluorescence emission of optimized N-CDs can be selectively quenched by Ni ions among other metal ions. Furthermore, the synthesized N-CDs are employed as fluorescent probes for the quantitative detection of Ni ions with a wide concentration range and a high sensitivity (the limit of detection approaching 1.58 nM). Overall, the current work reveals a new possibility for expanding the synthesis route and metal ion sensing of nitrogen-doped CDs.