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Synthesis of a conjugated polymer for sensing ferric/ferrous cations based on dual responses
Author(s) -
Zhang Yichen,
Zhan Hao,
Chen Jiajun,
Sun Lijuan,
Fan LiJuan
Publication year - 2020
Publication title -
journal of polymer science
Language(s) - English
Resource type - Journals
eISSN - 2642-4169
pISSN - 2642-4150
DOI - 10.1002/pol.20200231
Subject(s) - conjugated system , chemistry , excited state , polymer , fluorescence , ferric , ferrous , rhodamine b , solubility , photochemistry , quenching (fluorescence) , ring (chemistry) , polymerization , side chain , rhodamine , polymer chemistry , inorganic chemistry , organic chemistry , catalysis , physics , quantum mechanics , photocatalysis , nuclear physics
A conjugated polymer (PPETE‐RB) with poly[ p ‐(phenylene ethynylene)‐ alt ‐(thienylene‐ethynylene)] (PPETE) as the backbone with pendant rhodamine B (RB) groups in the close‐ring spirolactam form was synthesized. With long spacer between backbone and pedant groups as well as long solubilizing side chains, the polymer possesses good solubility in most organic solvents and relatively large molecular weight. The fluorescence of the conjugated polymer in THF exhibited selective dual responses upon adding Fe 3+ /Fe 2+ but negligible response upon other cations. The emission around 481 nm (excited at 360 nm) decreased and that around 571 nm (excited at 520 nm) emerged and increased when increasing the concentration of iron ions. The responses to Fe 3+ and Fe 2+ are very similar. The limits of detection were found to fall in between 6 μM and 8 μM. The mechanism study showed that the quenching around 481 nm was due to the inner filter effect (IFE) between the Fe 3+ /Fe 2+ and PPETE‐RB; while that enhancement around 571 nm could be attributed to the formation of fluorescent ring‐open structure from nonfluorescent spirolactam of pedant RB group upon Fe 3+ /Fe 2+ . Such dual and opposite responses provided more reliable information than single response for sensing applications.