Near-infrared benzodiazoles as small molecule environmentally-sensitive fluorophores

The development of fluorophores emitting in the near-infrared spectral window has gained increased attention given their suitable features for biological imaging.In this work,we have optimised a general and straightforward synthetic approach to prepare a small library of near-infrared-emitting C-bridged nitrobenzodiazoles using commercial precursors.C-bridged benzodiazoles have low molecular weight and neutral character as important features that are not common in most nearinfrared dyes.We have investigated their fluorescence response in the presence of a wide array of 60 different biomolecules and identified compound 3i as a potential chemosensor to discriminate between Fe2+and Fe^(3+)ions in aqueous media.