From nonconjugation to conjugation: novel meso-OH substituted dipyrromethanes as fluorescence turn-on Zn2+ probes†
Abstract
Most reported Zn2+ probes suffer from the interference of background fluorescence originated from the conjugated structures of commonly utilized fluorophores. In this work, three novel meso-hydroxyl group substituted dipyrromethanes DPMOH1–DPMOH3 were synthesized and found to be colourless and nonfluorescent due to the interruption of the conjugated π system by an sp3 carbon between the two pyrrolic units. Interestingly, only the addition of Zn2+ to the solutions of DPMOH1–DPMOH3 promoted their