Pyrophosphate selective fluorescent chemosensors: cascade recognition of nuclear stain mimicking DAPI

Abstract

A new zinc(II) complex with a condensed hydroxynaphthyl pyridine (SPHN) as the coordinated ligand has been synthesized for the selective recognition of pyrophosphate (PPi) over other anions including phosphate in a mixed aqueous solution. The fluorescence enhancement of SPHN in association with Zn²⁺ ions is quenched in the presence of intracellular pyrophosphate. This phenomenon is utilized in the construction of a logic gate. The binding of SPHN with Zn²⁺ and its displacement by PPi have been established by photophysical investigation and supported by the DFT level of studies. The development of blue fluorescence in the {SPNH–Zn} complex upon binding of zinc with SPHN is shown to be useful as a nucleus marker in a cell similar to the commercially available staining compound, DAPI (diamino-2-phenylindole).