A series of functional polyacetylenes bearing the fluorene moiety with different conjugated lengths and terminal substituents, poly[2-ethynyl-7-(4-nitrostyryl)-9,9-dioctyl-9H-fluorene] (P1), poly[2-ethynyl-7-(4-(4-nitrostyryl)styryl)-9,9-dioctyl-9H-fluorene] (P2), poly[2-ethynyl-7-(4-(4-methoxystyryl)styryl)-9,9-dioctyl-9H-fluorene] (P3), poly[2-ethynyl-7-(4-(4-methylstyryl)styryl)-9,9-dioctyl-9H-fluorene] (P4), and poly[2-ethynyl-7-(4-(4-methylstyryl)styryl)-9,9-didodecyl-9H-fluorene] (P5), were designed and prepared using [Rh(nbd)Cl]2 as the catalyst. Their structures and properties were characterized and evaluated by FTIR, NMR, UV, FL, GPC and TGA analyses. The optical limiting properties were investigated using 450 fs laser pulses at 780 nm. These results show that the incorporation of styryl/stilbene functionalized polyfluorenylacetylenes has endowed resultant polyacetylenes with novel near-infrared laser protection properties and enhanced thermal stability. The optical limiting mechanism for laser protection was studied. It was found that the optical limiting properties mainly originated from two-photon absorption (TPA) of molecules in the resulting polyacetylenes. Additionally, it was also found that the functionalized polyacetylene with a longer fluorene-based conjugated chromophore and a stronger terminal electron acceptor group exhibits better optical limiting properties because of the larger π-electron delocalization and dipolar effect.

•The 3D ternary composite (rGO/Fe3O4/PANI) was constructed via in-situ hydrothermal polymerization methods.•Its electrochemical activities was improved by synergistic effect between components.•Specific capacitance was enhanced greatly from PANI (299.1 Fg−1) to rGO/Fe3O4/PANI (486.5 Fg−1).•rGO/Fe3O4/PANI electrode showed improved retention ratio compared to pure PANI.To develop a promising electrode candidate for high-performance supercapacitors, a novel 3D ternary composite, graphene-Fe3O4-polyaniline (rGO/Fe3O4/PANI), was designed and developed via in-situ hydrothermal polymerization methods. After its structure and performances were characterized by powder X-ray diffraction, scanning electron microscope, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, ultraviolet-visible absorption spectroscopy and Brunauer-Emmett-Teller (BET), the electrochemical enhanced mechanisms for supercapacitor electrodes were explored carefully. By virtue of the excellent synergistic effect among Fe3O4, PANI and rGO, the electrochemical properties of rGO/Fe3O4/PANI-based electrode for supercapacitor were improved greatly. The specific capacitance increased from 299.1 Fg−1 for PANI, to 371.1 Fg−1 for rGO/PANI and further to 486.5 Fg−1 for rGO/Fe3O4/PANI. Importantly, even after 2000 cycles, the retention ratio could still keep 52.1% for rGO/Fe3O4/PANI comparing with 38.9% for PANI.Download high-res image (246KB)Download full-size image

•A fluorescein-based derivative was developed with improved solubility and fluorescent property.•It is a potential fluorescence-enhancement probe of Hg2+.•The detection is sensitive and successful in aqueous and living cells.•Recognition mechanism is confirmed to be 1:1 five-member rings between ACFH and Hg2+.To improve the water-solubility of heavy-metal sensing materials, a modified fluorescein-based derivative, acryloyl fluorescein hydrazine (ACFH), was designed and developed by incorporating a non-hydrogen-bonding group into the conjugated molecule for weakening intermolecular hydrogen-bonding interactions. In neutral water environments, ACFH presented a fluorescence-enhancement performance at λmax=512 nm in the presence of Hg2+, which could be visualized by naked-eyes. Under the optimized conditions, the linear range of Hg2+ detection was 1.0–100×10−9 mol L−1 with a correlation coefficient of 0.9992 and a detection limit of 0.86×10−9 mol L−1. The recognition mechanism was confirmed to be a stable and irreversible 1:1 five-member ring complex between ACFH and Hg2+ with a coordination constant of 3.36×109. ACFH would possess a potential application in detecting Hg2+ for biological assay with low cytotoxicity.Download high-res image (294KB)Download full-size imageTo improve the water-solubility of heavy-metal sensing materials, a modified fluorescein-based derivative, acryloyl fluorescein hydrazine (ACFH), was designed and developed by incorporating a non-hydrogen-bonding group into the conjugated molecule for weakening intermolecular hydrogen-bonding interactions. In neutral water environments, ACFH presented a fluorescence-enhancement performance at λmax =512 nm in the presence of Hg2+, which could be visualized by naked-eyes. Under the optimized conditions, the linear range of Hg2+ detection was 1.0–100×10−9 mol·L−1 with a correlation coefficient of 0.9992 and a detection limit of 0.86×10−9 mol·L−1. The recognition mechanism was confirmed to be a stable and irreversible 1:1 five-member ring complex between ACFH and Hg2+ with a coordination constant of 3.36×109. ACFH would possess a potential application in detecting Hg2+ for biological assay with low cytotoxicity.

Four novel triazole bridge-linked fluorene derivatives with different terminal push/pull substituted groups were designed and controlledly synthesized via click chemistry based on Huisgen 1,3-dipolar cycloaddition reaction in high yields. Their structures were characterized and evaluated by FTIR, 1H NMR, 13C NMR, MS and elemental analyses, respectively. The results show that these triazole bridge-linked fluorene optical materials are almost prepared quantificationally by click chemistry. The intramolecular charge transfer (ICT) in these triazole bridge-linked fluorene optical materials was investigated by molecular emission and absorption spectra, and further confirmed by cyclic voltammetry (CV) technology and theoretical simulation calculation. It is found that the intramolecular charge transfer is significantly affected by molecular structure. ICT emission, ICT/locally excited (LE) mixture emission and LE emission were achieved by changing the terminal group in triazole bridged conjugates.Highlights► Four novel triazole bridged fluorene derivatives with different push/pull substituents were synthesized via Click Chemistry. ► The influences of triazole unit on molecular structure and intramolecular charge transfer were discussed in detail. ► ICT, ICT/LE and LE emission were achieved by adjusting the structure of terminal group in triazole bridged conjugates. ► Excite-state TICT, partial excite-state ICT and ground state CT absorption were observed in T1, T2/T3 and T4, respectively.

To further investigate the influence of dye architecture on dye-sensitized solar cell (DSSC) performance, some near-infrared absorbing quinoline-based squaraine dyes (4a, 4b, and 4c) with different conjugated degrees carrying carboxylic or sulfonic groups as anchoring groups were designed, prepared, and applied as sensitizers in solar cells. The photophysical and photochemical studies showed that photoelectric conversion efficiencies (η) are significantly affected by molecular structures; i.e., η of 4c with the strongest polarity and anchoring ability and the longest π electron conjugated degree was two times more than that of 4b and six times more than that of 4a. That is, the molecules with smaller optical band gap and higher molar absorption coefficient will possess better light-harvesting properties and enhanced conversion efficiency. Furthermore, all excited state orbitals relevant for the π–π electron transition both in 4b and 4c are delocalized over the anchoring groups, ensuring a strong electronic coupling to the conduction band of TiO2 and hence a fast electron transfer.

In this contribution, a new, real-time and sensitive colorimetric sensor, di-N-methyl-N-hydroxyethylaniline squaraine (SQ), has been identified and synthesized for cysteine analysis based on its ΔA in neutral aqueous medium (pH ≈ 7.5). The proposed method was applied to analyse synthetic amino acid samples and human serum samples. The results show that the linear range of cysteine detection in aqueous medium at pH ≈ 7.5 is 10∼700 nmol L−1 with a correlation coefficient (R) of 0.9984 and a limit of detection (3σ, n = 20) of 3.9 nmol L−1. The relative standard deviation (RSD) for cysteine detection was lower than 4.1% (n = 5). The proposed method possesses the advantages of simplicity, rapidity, high selectivity and sensitivity. This makes it possible, for the first time, the real-time detection of cysteine under normal physiological conditions.

A novel functional polyacetylene with D-π-A conjugated quinoline-based heterocyclic azo pendants was designed and prepared to improve the polyacetylene properties. Its structure and properties were characterized and evaluated in details. The incorporation of D-π-A conjugated quinoline-based heterocyclic azo pendants to the polyacetylene backbone increases the polymer solubility in polar solvents. Its UV-vis absorbance is sensitive to the presence of F− anions and results in UV-VIS spectrum red-shift by ca. 21 nm from 449 nm to 470 nm in dry DMSO.

The controllable preparation and forming mechanism of rare-earth Y3+ and Eu3+ chemically co-doped fluorescent mesoporous silica were studied in detail. Their structures, morphologies, chemical compositions and emission properties were characterized and evaluated by small angle X-ray scattering, nitrogen adsorption/desorption measurements, high resolution transmission electron microscopy, inductive coupled plasma-atomic emission, X-ray photoelectron spectra and fluorescent spectroscopy. The results show that chemical composition of the resultant mesoporous materials were significantly affected by solution acidity condition, and can be effectively adjusted by varying the feed ratio of raw materials at a suitable solution acidity condition. These materials with a well-ordered two-dimensional hexagonal mesoporous structure and high specific surface area exhibit significantly broadened emission band from 526 to 682 nm and the fluorescent emission mechanism and influence of materials structure on optical properties were investigated.The Y3+ and Eu3+ co-doped well-ordered mesoporous silica through direct incorporation of rare-earth ions into wall of mesoporous materials show a widened emission band.