Amino acid-functionalized polyfluorenes: A class of ultra-sensitive fluorescent sensors favoring Cr₂O₇^2-

Conjugated polymers (CPs) are an intriguing material to build fluorescent Cr₂O₇^2- sensors with excellent sensitivity but often lack specific recognition groups. In this study, several typical amino acids with N and O atom identifying groups were incorporated into fluorene and then six polyfluorene derivatives were synthesized using electrochemical polymerization. Compared to other cations and anions, all of these amino acid-functionalized polyfluorenes have good selectivity towards Cr₂O₇^2- and enable ultra-trace response with detection thresholds at pM or even fM level.