2-Benzylidene-1-benzofuran-3(2H)-ones (aurones) are natural pigmented compounds found in certain types of flowering plants. Aurones have also been shown to have useful fluorescent properties, including a large Stokes shift, and modifiable emissions spectra. Similarly, 1,2,3-triazoles have been previously reported to also have useful fluorescent properties including large Stokes shifts and have been explored for their use as fluorescent probes <i>in vitro</i>. Recently, 1,2,3-triazole containing compounds were synthesized as an unintended byproduct during an attempt to add an azido moiety to aurones. We hypothesized that these accidental aurone-derived 1,2,3-triazoles (AT) would have unique fluorescent properties including a large Stokes shift and have potential use as biologically relevant fluorescent probes. We analyzed multiple different ATs for fluorescence in live cells and found AT5 as a viable candidate for live-cell microscopy in certain cell types. Though insoluble in water, AT5 was also shown to have a large Stokes shift of 118.53±1.33nm in PBS, with the highest emissions occurring in polar protic solvents as opposed to polar aprotic and non-polar solvents. Emission intensities in detergent micelle models were also shown to be charge dependent. At lower SDS concentrations the fluorescence of AT5 was initially quenched, but emissions slightly increased at concentrations approaching and immediately above the CMC. In CTAB however, emissions were quenched at concentrations leading to the CMC with slight recovery at concentrations above the CMC. Here we show AT5 as a new fluorophore with a large Stokes shift, which is not sensitive to pH, with increased emissions in polar protic solvents, which makes it unique from other aurone-derived fluorescent probes.

Fluorescent properties of aurone-derived triazoles

ACS Spring 2022

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