N-alkylated diketopyrrolopyrrole-based ratiometric/fluorescent probes for Cu2+ detection via radical process

摘要

Two N-alkylated diketopyrrolopyrrole derivatives, namely, FDPP-C8 and TDPP-C8, were prepared and applied in the ratiometric and fluorescent detection of Cu2+ in acetonitrile. The distinct optical changes of two probes were attributed to the fast radical process of diketopyrrolopyrrole triggered by Cu2+. This reaction mechanism was investigated by NMR, MS and EPR experiments and DFT theoretical calculations. The detection of Cu2+ with FDPP-C8 and TDPP-C8 were completed instantaneously, making them convenient for practical real-time operation. The limits of detection of FDPP-C8 and TDPP-C8 for Cu2+ were calculated as 65 and 127 nM, respectively. Relevant competitive ions exerted no effect. In addition, the intrinsic two-photon absorption properties of FDPP-C8 were also investigated and successfully used in the detection of Cu2+. Furthermore, given that Cu2+/Cu+-involved radical process is solvent dependent, TDPP-C8 was used to construct a INHIBIT logic gate at the molecular level with DMF and Cu2+ as inputs.