NIR-region two-photon fluorescent probes for Fe3+/Cu2+ ions based on pyrimidine derivatives with different flexible chain

Two novel NIR-region two-photon fluorescent probes CCP and COP, show strong fluorescence quenching and good ratiometric responses toward Fe3+ and Cu2+, respectively; and their two-photon fluorescence are reversible by the subsequent addition of EDTA. CCP and COP are valuable candidates for two-photon imaging in the biological transparency window.