Yinyin Bao

An efficient conjugated polymer sensor based on the aggregation-induced fluorescence quenching mechanism for the specific detection of palladium and platinum ions

Based on the aggregation-induced fluorescence quenching mechanism, a 2,6-dithienyl-4-phenylpyridine-containing conjugated polymer (P-A) has been designed and synthesized via a Sonogashira coupling reaction as an efficient fluorescent sensor for palladium and platinum ions. The metal ion-sensitivity of P-A was evaluated using a series of transition metal ions in aqueous solution. On binding to Pd2+ or Pt4+, fluorescence quenching of P-A was demonstrated by an approximately 80% reduction in the fluorescence intensity, while no obvious fluorescence change could be observed in the presence of other metal ions. Compared with its small molecular counterpart, P-A exhibits higher sensitivity and selectivity. The fluorescence intensity of P-A has shown a linear response to both Pd2+ and Pt4+ in the concentration range of 1–10 μM with a detection limit of 1 × 10−6 M in aqueous solution. It has been demonstrated that the sensitive property of the polymer sensors for the palladium and platinum ions is highly dependent on the fine structure of the conjugated polymers. The fluorescence quenching can be attributed to the Pd/Pt-induced aggregation of the polymer chains, which has been proved by fluorescence anisotropy methods. These results indicate that the fluorescence-amplifying method based on the aggregation-induced fluorescence quenching mechanism has enormous potential for the development of highly efficient fluorescence sensors towards the detection of palladium and platinum ions.

POSS-containing red fluorescent nanoparticles for rapid detection of aqueous fluoride ions

Polyhedral oligomeric silsesquioxane (POSS)-containing red fluorescent nanoparticles were designed and prepared for rapid detection of aqueous fluoride ions by virtue of the fluoride-triggered self-quenching of perylene bisimide dyes in nanoparticle cores.

A new strategy for highly selective fluorescent sensing of F− and Zn2+ with dual output modes

A new strategy for highly selective and sensitive detection of both F− and Zn2+ with dual output modes was developed, which is based on a combination of F− induced desilylation reaction and chelation-enhanced fluorescence effect caused by Zn2+.

A highly sensitive and selective ratiometric Cd2+ fluorescent sensor for distinguishing Cd2+ from Zn2+ based on both fluorescence intensity and emission shift

A highly selective ratiometric fluorescent sensor for Cd2+ has been successfully prepared, which can distinguish Cd2+ from Zn2+ with both fluorescence intensity and emission shift. The detection limit is down to nanomolar range concentration in aqueous solution.

2,6-Substituted pyridine derivative-containing conjugated polymers: synthesis, photoluminescence and ion-sensing properties

This paper describes a strategy to design and synthesize novel 2,6-substituted pyridine derivative-containing conjugated polymers for metal ion sensing. Two polymers P-1 and P-2 were prepared and the ion sensing properties of the monomers and the polymers were examined by UV-Vis absorption and fluorescence spectra respectively. It was found that polymer sensor P-1 exhibited a high selectivity for palladium ions among various transitional metals. The main absorbance peak was enhanced and a new peak appeared with the addition of palladium ions, meanwhile a linear calibration curve was observed. Moreover, the fluorescence intensity of emission maximum also decreased dramatically with a detection limit of 1 × 10−6 M in aqueous solution. These results indicate the polymer P-1 can be used as a novel sensor for Pd2+ detection with high sensitivity and selectivity. The excellent performance of the polymer for Pd2+ detection can be attributed to the structure of the modular-based conjugated polymer with the meta-substituted pyridine, which provides a proper spatial matching for selective binding of metal ions and this is very important for designing polymer sensors for metal ions.

Conjugated coordination polymers based on 8-hydroxyquinoline ligands: impact of polyhedral oligomeric silsesquioxanes on solubility and luminescence

A novel bis(8-hydroxyquinoline) zinc-based conjugated coordination polymer with polyhedral oligomeric silsesquioxanes (POSSs) in the side chains has been synthesized. In contrast to the traditional coordination polymers, this new coordination polymer has good solubility in common organic solvents and can be characterized and processed in solution. The thermal stability of the polymer is also enhanced by POSSs and the fluorescence is not quenched by intermolecular aggregation in the solid state. This fluorescence enhancement is due to the significant effect of the bulky POSS units. Nanoparticles is obtained by a facile self-assembly method of the polymer materials and the nanoparticles show strong fluorescence at 545 nm.

A facile and highly efficient strategy for esterification of poly(meth)acrylic acid with halogenated compounds at room temperature promoted by 1,1,3,3-tetramethylguanidine

Esterifications of poly(methacrylic acid) (PMAA) and poly(acrylic acid) (PAA) have been investigated with a wide variety of halogenated compounds such as iodide, bromide, and chloride using 1,1,3,3-tetramethylguanidine as a promoter. The results demonstrate that the poly(meth)acrylates can be obtained with an excellent degree of esterification at room temperature. The influence of solvent, reaction conditions, and halogenated compounds on the esterification reaction was examined. It was found that polar solvents, such as dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF), are favorable for the esterification and high degree of esterification can be achieved in a short time. Moreover, the esterification reaction of PMAA has been successfully performed in an aqueous solution of DMSO, which indicates that the solvent does not necessarily have to be dried for this reaction. Primary and secondary halogenated compounds can successfully react with PMAA or PAA, while tertiary halogenated compounds fail to react. In addition, combining this esterification reaction with atom transfer radical polymerization (ATRP), macromonomers were conveniently prepared by the reaction of halogen-capped polymers with methacrylic acid under mild conditions.

An amphiphilic conjugated polymer as an aggregation-based multifunctional sensing platform with multicolor fluorescence response

We designed and synthesized an amphiphilic conjugated polymer P1 based on the 2,2′-biimidazole unit, and then investigated its sensing properties as an aggregation-based platform. P1 shows multicolor emission in organic solvents at different water contents, and is demonstrated to be the first multicolor fluorescent sensor for water. And it exhibits visually noticeable multicolor fluorescence response to Ag+ in aqueous dioxane and to Hg2+ ions in aqueous ethanol. In addition, the polymer–Hg2+ complex system can be used as an efficient cysteine fluorescent sensor based on the aggregation–disaggregation strategy. These results validate P1 as an efficient multifunctional platform with multicolor fluorescence response.