Water-soluble pyrrolopyrrole cyanine (PPCy) near-infrared fluorescent pH indicators for strong acidity†
Abstract
Water-soluble, fluorescence-switchable derivatives of pyrrolopyrrole cyanines (PPCys) which serve as near-infrared pH indicators have been synthesized. The dyes reported have pKa values of 2.4–3.4 and thus are suitable for sensing in highly acidic environments. The new pH probes were evaluated by fluorescence imaging experiments in a cellular environment.