Synthesis and Spectrophotometric Studies of Heterocyclic Bay-Substituted Naphthalenediimide Colorimetric pH Indicators

Four naphthalenediimide colorimetric pH indicators were synthesized with N,N-dimethylethyleneamine at the imide positions and 5- to 7-membered heterocyclic rings bay positions, namely pyrrolidine, morpholine, piperidine azepane. The are constructed in a modular receptor–spacer–fluorophore–spacer–receptor format based on photoinduced electron transfer (PET) design. compounds studied by UV–visible absorption steady-state fluorescence spectroscopy 1:1 (v/v) methanol/water. Brilliant colour changes observed between 2 4 due an internal charge (ICT) mechanism. Fluorescence turn-on enhancements range from 10–37 fold; however, maximum quantum yield presence of acid is <0.004, which below naked eye detection. Hence, viewpoint human observer, these chemosensors function as YES logic gates, fluorimetric PASS 0 gates.