An Al-salen complex for the fluorometric detection of pyrophosphate in water via a disassembly approach

Abstract

This report describes the selective fluorometric detection of pyrophosphate in water with a simple Al[Formula: see text]-salen complex. The Al-based probe is synthesized in two steps in 30% yield and disassembled in the presence of pyrophosphate into its molecular building blocks. The released 3-chlorosalicylaldehyde signaling unit leads to a detectable signal with a 29-fold increase in fluorescence ([Formula: see text] = 513 nm; [Formula: see text] = 388 nm). At this emission wavelength, we did not observe a response from the Al[Formula: see text]-salen probe despite its intrinsic blue fluorescence ([Formula: see text] = 460 nm;[Formula: see text][Formula: see text] = 347 nm). The Al[Formula: see text]-complex shows excellent discrimination of pyrophosphate over other ions including phosphate containing adenosine triphosphate, phytic acid, or glyphosate and only fluoride inhibits the pyrophosphate-triggered disassembly process. Related salen-based probes with the same hydrophobic ligand framework but either Zn[Formula: see text] or Fe[Formula: see text] ions instead of Al[Formula: see text] were not sufficiently robust and therefore not suitable for analytical applications in pure water at pH 7.4.