Synthesis and chemosensory application of water-soluble polyfluorenes containing carboxylated groups

Abstract

Detection of metal ions in aqueous solutions is a major issue for environmental protection. Conjugated polyelectrolytes showing high sensitivity and selectivity towards the detection of metal ions are highly desirable. We report a water-soluble polyfluorene containing carboxylated groups (P1), poly[9,9'-bis(3''-propanoate)fluoren-2,7-yl] sodium salt, which shows high recognition capability toward Cu(+) and Cu(2+). P1 was prepared via the hydrolysis of poly[9,9'-bis(tert-butyl-3''-propanoate)fluoren-2,7-yl] (P0) which was synthesized by Suzuki coupling polymerization. The photoluminescence (PL) spectra of P1 in aqueous solution are significantly quenched in the presence of Cu(+) and Cu(2+). P1 shows high selectivity and sensitivity toward Cu(+) and Cu(2+), with the Stern-Volmer constants (Ksv) being 3.5 × 10(6) and 5.78 × 10(6) M(-1), respectively. Moreover, the stoichiometric ratio of the P1 repeat unit to Cu(+) or Cu(2+) is 2 : 1 obtained from Job's plot. P1 maintains high selectivity towards Cu(+) or Cu(2+) in the presence of various metal cations. Our results demonstrate that P1 shows very high sensitivity and selectivity in recognizing Cu(+) and Cu(2+), indicating that it is a promising functional material for chemical sensors.

Hydroxyethyl cellulose filled with M2+ chelate complexes with ethylenediaminetetraacetic acid (EDTA) as an effective electron-injection layer for polymer light-emitting diodes

“…On the other hand, the chelates (chelate complexes) by acetate group (CH 3 COO À ) are sandwich-like structures (Fig. 8) or other bidentate chelating modes [53,57]. The chelation capability of EDTA 4À is obviously more powerful than that of the acetate group.…”

Temporally Programmed Disassembly and Reassembly of C3Ms

“…In good solvent conditions, alkyl‐substituted polyfluorenes maintain a semiflexible chain conformation which influences its spectral features. Its fluorescence emission displays a main emission band at 415 nm and two weak bands at 436 and 465 nm . In poor solvent conditions, for example at low pH for our CPF due to the protonation of the carboxylated side chains, a transition from a dissolved state to an “aggregate” state occurs, which is commonly observed via the vibronic progressions in fluorescence spectra of polyfluorenes .…”

“…Electrons travel along the conjugated backbone, leading to electronic delocalization which affects the electronic properties of the entire polymer . This signal amplification makes it possible to detect very subtle changes in the environment or low levels of analyte binding . The fluorescence response varies from the enhancement to quenching of emission intensity or even from vibronic progressions to bathochromic shifts.…”

“…We benefit from the coupling between pH‐dependent conformations and spectral features of polyfluorenes to interpret the spectral readouts of our CPF during the AFS programmed pH cycle. Additionally, CPF reports on analyte binding as fluorescence quenching . This enables us to detect the complexation of CPF initially with the tracer molecule to form the intermediary complex, followed by complexation with the DBP to form C3Ms.…”

Cationic Main‐Chain Polyelectrolytes with Pyridinium‐Based p‐Phenylenevinylene Units and Their Aggregation‐Induced Gelation

“…Side‐ or main‐chain polyelectrolytes that contain charged, π‐conjugated repeat units are an interesting class of materials for potential applications in chemo‐ or biosensing as well as optoelectronic devices such as solar cells or organic light emitting diodes . In recent years, side‐chain conjugated polyelectrolytes based on several backbone motifs were developed including polyfluorenes, fluorene–benzothiazole copolymers, polythiophenes, poly‐ p ‐phenylenevinylenes, poly‐ p ‐phenyleneethynylenes among others for applications in sensing, imaging, as well as for enzyme activity, and charge transport studies . Fully conjugated poly(pyridinium salt)s, or polyelectrolytes containing viologen, as well as diethynylpyridinium units as main‐chain polyelectrolytes have been synthesized mainly for biosensing and optoelectronic applications.…”