•A novel π-conjugated polymer was synthesized by a Suzuki coupling reaction.•The polymer has good thermal stability and excellent photoelectric properties.•The polymer as a fluorescence probe exhibits high selectivity and sensitivity for Fe(III).•The probe can be used to detect Fe(III) in biological system.A novel π-conjugated polymer comprised of 8-methoxyquinoline and benzene groups has been successfully synthesized and characterized. The polymer exhibits good photo and thermal stabilities with decomposition temperature (Td) of 240 °C and glass transition temperature (Tg) of 325 °C. The maximum absorption and emission wavelengths of the polymer are 325 nm and 430 nm with a high fluorescence quantum yield (0.74) in chloroform, respectively. The electrochemical properties of the polymer were investigated with the cyclic voltammetry method, and the results agreed with the data of theoretical calculation by the Gaussian 09 software. Based on the excellent photoelectric properties, the polymer as a fluorescent probe was used to detect metal ions in solution and biological cells. Experimental results indicate that the polymer has a high selectivity and sensitivity for Fe3+ with the fluorescence quenched processes. Noticeably, the detection of the polymer for Fe3+ can be processed in biological system.

•A novel conjugated polymer (PFP) comprised of fluorene, benzene and alkoxy units was designed and synthesized.•The corresponding CPNs exhibit high photostability, good biocompatibility and low cytotoxicity.•The CPNs can stain the tumor cells and locate in the cytoplasm.•The CPNs display high selectivity and sensitivity for Fe(III) in water.A novel conjugated polymer (PFP) comprised of fluorene, benzene and alcoxyl units was synthesized by a Suzuki coupling reaction between fluorene borate and dibromobenzene derivant. Due to its longer alcoxyl groups in the side chain, PFP polymer possesses good solubility in common organic solvents. Accordingly, conjugated polymer nanoparticles (CPNs) from PFP polymer were easily prepared by a re-precipitation method. A spherical structure of the CPNs with an average diameter of ~75 nm was verified by dynamic light scattering (DLS) and scanning electron microscopy (SEM). The CPNs exhibit high photostability, good biocompatibility and low cytotoxicity. Based on these excellent properties, the CPNs as staining and labeling regents were used to cell imaging and located in the cytoplasm. Interestingly, the fluorescent probe based on CPNs displays high selectivity and sensitivity for Fe(III) in water because of the aggregation-induced fluorescence quenching action between CPNs and Fe(III). The contribution of the report lies in providing a new strategy for designing and developing CPNs-based probes, and applying in the interdisciplinary fields of chemistry, biology and material sciences.

Conjugated polymer nanoparticles composed of PFT/PS as a core and PEG-COOH on the surface were prepared by a reprecipitating method. The CPNs diaplay excellet properties such as good photostability, low cytotoxicity, and strong brightness, etc. The average diamater of CPNs is 30 nm with a spherical morphology. To realize specific imaging in different parts of tumor cells, the bare CPNs with the carboxyls on the surface were conjugated with antibody or peptide by a covalent mode. Studies display that CPNs modified with anti-EpCAM can recognize MCF-7 tumor cells and locate on the membrane, while CPNs conjugated with transcriptional activator protein (Tat) specifically locate in the cytoplasm of MCF-7 cells. On the basis of the ability of CPNs for producing reactive oxygen species (ROS) under light irradiation, photodynamic therapy for tumor cells was investigated. Due to the long distance and wide diffusion range, MCF-7 tumor cells with CPNs/anti-EpCAM have no obvious change with or without white light irradiation. However, CPNs/Tat exhibits higher killing ability for MCF-7 cells. Noticeably, multifunctional CPNs linked with anti-EpCAM and Tat simultaneously not only can specifically target MCF-7 tumor cells, but also may inhibit and kill these cells. This work develops a potential application platform for multifunctional CPNs in locating imaging, photodynamic therapy, and other aspects.Keywords: cell imaging; conjugated polymer nanoparticles; functionalization; photodynamic therapy; preparation

•Two novel blue emitting OLED materials were designed and synthesized.•These emitters exhibit good thermal stability and electron transfer properties.•The device with BCP emitter has good optical and electrical characteristics.Two blue emitters, 2,7-bis(9-benzyl-9H-carbazol-2-yl)pyrene and 2,7-bis(4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl)pyrene, were synthesized by a Suzuki coupling reaction. Photophysical studies show that the two emitters have excellent optical and electron transfer properties. The emission peaks of the two emitters are 430 nm and 439 nm with 87.5% and 68.6% fluorescence quantum yields in chloroform, respectively. The emitters both have good thermal stability (Td > 330 °C, Tg > 160 °C). Electrochemical Redox properties of the emitters were measured by cyclic voltammetry, and the highest occupied molecular orbital and the lowest unoccupied molecular orbital levels are in good agreement with the results of theoretical calculations. Additionally, non-doped blue organic light-emitting diodes with these emitters have been achieved with the Commission International de l’Éclairage (x,y) coordinates of (0.17, 0.11) and (0.16, 0.15) respectively, which are very close to the National Television System Committee standard blue. Remarkably, the performance of device A (2,7-bis(9-benzyl-9H-carbazol-2-yl) pyrene) offers balanced performance and without any significant disadvantages.

A facile fluorescence receptor was easily synthesized by an one-step reaction of 3,4-dihydroxybenzaldehyde and hydrazinecarbothioamide. The receptor as a fluorescence probe was used to recognize metal ions by UV-vis and fluorescence techniques. The data of UV-vis and fluorescence spectra display the high sensitivity and selectivity of the receptor for Al(III) ions. When introducing Al(III) ions, the fluorescence of the probe exhibits an obvious enhancement because of inhibiting the photoinduced electron transfer (PET) process. The certain bonding mode of the receptor with Al(III) was verified by 1H NMR, HRMS-ESI and Job-plot data. The prospective fluorescence “Off–On” signal for Al(III) ions including the color change of the receptor solution was observed. The detection limit of the receptor for Al(III) may reach 10−7 mol L−1. Noticeably, the probe as a fluorescence “Off–On” switch can detect the trace level of Al(III) in living cells and mouse organs. The work provides a strategy for design simple fluorescence probes for Al(III) and applications in biological systems.

•A simple and efficient chemosensor HPIN is designed and synthesized.•The chemosensor has high selectivity and sensitivity for Al3 +.•It is a fluorescence “off–on” switch for Al3 +.•The coordination mode of HPIN with Al3 + is a 1:1 binding stoichiometry.•Potential utilization of HPIN as intracellular sensors of Al3 + was examined.A simple and efficient fluorescent chemosensor for Al3 + is reported in the paper. The chemosensor is obtained by dehydration reaction of 2-hydroxy-1-naphthaldehyde and 2-aminophenol. The chemosensor has high selectivity and sensitivity for Al3 + and displays fluorescence “off–on” switch signal. The detection limit of the chemosensor for Al3 + can reach 1.0 × 10− 7 M in DMSO/H2O (1:9, v/v) solution. The mass spectra and Job's plot analysis confirm the 1:1 stoichiometry between chemosensor and Al3 +. Potential utilization of the probe as an intracellular sensor of Al3 + in human cancer (HiSa) cells is also examined by confocal fluorescence microscopy.

•A facile fluorescence switch with Schiff base units was designed and synthesized.•The fluorescence of the probe can be illumined by Al3 + ion.•The fluorescence of the probe/Al3 + ensemble may be quenched by Cu2 + ion.•It is a fluorescence “off–on–off” change probe by metal ions.•The regulation role of the probe can be applied in cell imaging.A facile fluorescence switch with Schiff base units was designed and achieved by nucleophilic addition and dehydration reaction. The fluorescence of the probe can be regulated by metal ions (Al3 + and Cu2 +). The whole process shows that the weak fluorescence of the probe enhances with the addition of Al3 +, and then the strong fluorescence of the probe/Al3 + ensemble reduces by introducing Cu2 +. Meanwhile, the solution color changes of the probe with metal ions can be observed under 365 nm UV–vis light from weak light, pale green, green, pale green to weak light. Noticeably, the photo regulation processes of the probe by metal ions can be realized in the biological system and applied in cells imaging. The work provides a new strategy for designing facile regulation probe and develops a new application for Schiff base derivatives.

•A novel blue emitting PLED material was designed and synthesized.•The polymer was comprised of hole-transfer, electron-transfer and luminescence groups.•The polymer exhibits good thermal stability.•The polymer possesses excellent electron transfer property.•The polymer has desired optical and electrical characteristics.A novel π-conjugated polymer (PCQH) containing N-benzylcarbazole and 8-methoxyquinoline units has been successfully synthesized and characterized. The polymer possesses good thermal stability with the decomposition temperature (Td) of 295 °C and the glass transition temperature (Tg) of 250 °C. The absorption and emission spectra show that the polymer can emit blue light with higher fluorescence quantum yield (81%) in CHCl3. With the increase of solvent polarity, the emission peaks of PCQH display an obvious red-shifted. The study of the interactions of PCQH with electron donor (DMA) and electron acceptor (DMTP) indicates that the polymer has excellent electron transfer property. Furthermore, the interactions of PCQH with carbon materials (C60 and CNTs) also have been investigated. The electrochemical properties and energy levels of PCQH were calculated by the Gaussian 09 software, which are correspond to the experiment detection with cyclic voltammetry method.

A specific fluorescent switch for anions was successfully constructed. The novel sensing switch is a two-component ensemble, which was combined using a water-soluble conjugated polyelectrolyte and a boronic acid functionalized pyridine salt. In the ensemble, the polyelectrolyte is used as a fluorescent signal unit, and the pyridine boronic acid acts as receptor and quencher. The two-component ensemble shows a fluorescence reversible “off–on” response toward cyanide and phosphate anions based on different binding ways. Furthermore, the facile design and construction of this ensemble presents a novel opportunity for obtaining an efficient and practical probe.Highlights► A facile ensemble for the detection of phosphate and cyanide ions is described. ► The ensemble is comprised of a polyelectrolyte and a pyridine salt. ► The ensemble shows afluorescence reversible “off–on” response toward anions. ► The mode opens up the way for developing highly efficient and practical probe.

•Three new ensembles for D-glucose detection are constructed.•These sensing ensembles are comprised of dye NAHBDS and quenchers BBVs.•Fluorescence reversible signals for D-glucose sensing are observed.•These ensembles show highly sensitive for D-glucose detection.•This research can provide a new strategy for molecular recognition.Three facile ensembles for sensing D-glucose are designed and constructed. The ensembles are comprised of fluorescent dye (NAHBDS) and boronic acid substituted viologens (BBVs) quenchers/receptors. The sensing processes of three ensembles (NAHBDS/o-BBV, NAHBDS/m-BBV and NAHBDS/p-BBV) to D-glucose were determined by fluorescence spectra at pH 7.4 buffer solution. The results show that NAHBDS/o-BBV and NAHBDS/m-BBV ensembles embody higher sensitivity for D-glucose with reversible “on–off” fluorescence response. More importantly, the recovery of relative intensity has good linear relation to low concentration of D-glucose. The action between the ensemble with D-glucose is dynamically reversible equilibrium process. The research results provide a new mode to design highly selective probe.Graphical abstract

•A novel π-conjugated polymer with blue light emission was established.•The polymer is comprised of carbazole and pyrene groups.•The polymer shows high thermal stability under 440 °C.•The polymer demonstrates high energy level of the HOMO (about −5.2 eV).•The polymer possesses high fluorescent quantum yields.A novel π-conjugated polymer (PCPyrene) containing N-benzylcarbazole and pyrene units has been synthesized and characterized. The polymer possesses high thermal stability with the decomposition temperature of 440 °C. It shows higher fluorescence quantum yields of in solution and solid state, respectively. PCPyrene can emit bright blue-lights both in different organic solutions (440–460 nm) and in the solid state (492 nm). Compared the emission spectra of PCPyrene in solutions with in solid state, the solid state emission of PCPyrene is significantly red-shifted. Additionally, it is not obvious changes of the solid emission spectra even after being annealed at 150 °C under nitrogen for 24 h. The electrochemical properties and energy levels of PCPyrene were also investigated by cyclic voltammetry. Furthermore, in order to provide a basis forecasting the structure–physical property relationships, the photophysical properties of PCPyrene have been carefully investigated by fluorescence emission and UV–vis absorption spectra.Graphical abstract

Three highly sensitive and selective switches for monosaccharides were composed by anionic polyelectrolyte PPPSO3Na and cationic viologen quencheres BBVs. The sensing processes of three ensembles (PPPSO3Na/o-BBV, PPPSO3Na/m-BBV and PPPSO3Na/p-BBV) to common seven monosaccharides have been determined by fluorescence spectra at pH 7.4 buffer solution. The results show that the three sensing ensembles all embody higher selectivity and sensitivity for d-fructose with reversible “on-off-on” fluorescence response. The research results can provide a new mode for developing highly selective probes.Graphical abstractHighlights► In the study we establish three sensing ensembles for d-monosaccharides. ► These sensing ensembles are comprised of polyelectrolyte and BBVs quenchers. ► The ensembles all show high selectivity and sensitivity for d-fructose in seven monosaccharides. ► The research results can provide a new strategy for molecular recognition.

A specific two-component ensemble probe has been designed and developed to detect cyanide ion in aqueous solution. It is comprised water-soluble fluorescence dye HPTS and boronic acid functionalized quencher/receptor TB3PB. The nucleophilic addition of cyanide ion to boronic acid groups of TB3PB yields an intramolecular complex which will weaken the electrostatic interaction of TB3PB and HPTS, and as a result, the fluorescence of HPTS recovers largely.

A novel fluorescence probe for d-glucose is formed by anionic dye NAHBDS and cationic boronic acid functionalized poly(benzyl viologen salts) q-BBV2+. The two-component probe showed reversible fluorescence “on–off” response for d-glucose. For probe, the specific bonding way of anionic dye and cationic polymer quencher/receptor provides an appropriate microenvironment and multidimensional bonding sites which actively catch d-glucose molecule.

A glucose sensing switch is formed by water soluble conjugated polymer (PP–S-BINOL) and boronic acid-functionalized benzyl viologen (o-BBV). The two-component system shows a high sensitivity for glucose sensing with a 17-fold increase in the fluorescence intensity in the presence of 100 mM glucose.

A novel luminescent compound 9,10-di-(N-carbazovinylene)anthracene (DCVA) was synthesized by Heck reaction of 9,10-dibromoanthracene and N-vinylcarbazole. The structure was characterized by MS, 1H NMR and Elemental analysis. The photoluminescent properties of DCVA have been carefully investigated by UV–vis absorption and fluorescence emission spectra. The results showed that the luminescent quantum yield of DCVA was 0.73 in THF and it emitted blue-light with the band gap of 3.60 eV estimated from the onset absorption. In addition, the light-emission of DCVA can be quenched by electron acceptor (dimethyl terephthalate), however, the fluorescent intensities of DCVA were slowly increased with the addition of electron donor (N,N-dimethylaniline). Furthermore, the molecular interactions of DCVA with fullerene (C60) and carbon nanotubes (CNTs) were also investigated, which indicated the organic luminescent compound can be used as new fluorescent probe.

An iodide-sensing, colormetric and selective fluorescent sensor N2,N6-bis(2-(p-nitro-benzamido)ethyl)pyridine-2,6-dicarboxamide, BBPCA, was reported. The recognition properties of BBPCA toward various anions were evaluated in THF/H2O (4/1, v/v) solution by fluorescence emission and UV–vis absorption spectra. The results showed the BBPCA can be used to detect iodide ion based on intermolecular charge transfer (ICT) and heary atom quenching mechanism. The color changes of BBPCA solution from colorless to yellow and a red-shift in the absorption and emission spectra can be observed by adding iodide ions. But it showed no significant changes on the addition of other anions such as F−, Cl−, Br−, HCO3−, NO3−, CO32−.

Three effective detection systems for glucose based on reversible “on–off” fluorescence recognition mechanism were developed. Fluorescent quantum dot (FQD) with amino and carboxyl groups were used as fluorescent reported section and its fluorescence was modified by boronic acid functional benzyl viologens (BBVs). The BBVs acted as both quenchers and receptors roles in these systems. The sensing systems of FQD/BBVs all displayed higher detection efficiency for glucose than organic-dye/BBVs system, especially for FQD/o-BBV sensing system. The glucose response signal showed 4-fold fluorescent intensity increase of FQD/o-BBV system only in the presence of 10.0 mM glucose.

A glucose sensing switch is formed by water soluble conjugated polymer (PP–S-BINOL) and boronic acid-functionalized benzyl viologen (o-BBV). The two-component system shows a high sensitivity for glucose sensing with a 17-fold increase in the fluorescence intensity in the presence of 100 mM glucose.