Abstract
The photophysical properties of a range of fluorescent sensors with β-aminobisphosphonate receptors have been studied. The compounds were designed according to the fluorophore–spacer–receptor format of photoinduced electron transfer-based sensors. The sensors displayed unusual fluorescence intensity–pH profiles that were attributed to a receptor–fluorophore H-bonding interaction that resulted in a quenching of fluorescence. The number of receptors and the nature of the fluorophore were both shown to have an effect on the pH profiles of the sensors. In addition, compound 1 was also shown to be selective for Cu2+ ions, in water at pH 7.4 with sensitivity in the micromolar range.
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Acknowledgements
The authors would like to thank RGU and the Leverhulme Trust, UK for financial support and Professor A.P. de Silva and Dr Bridgeen McCaughan for their helpful discussions. We also thank the EPSRC National Mass Spectrometry Service for the high-resolution spectra.