Triphenylamine‐based fluorescent conjugated copolymers with pendant terpyridyl ligands as chemosensors for metal ions

Two well‐defined triphenylamine‐based fluorescent conjugated copolymers with pendant terpyridyl ligands were synthesized through Suzuki coupling polymerization and were further characterized by ¹H‐NMR, ¹³C‐NMR, gel permeation chromatography, Infrared, and UV‐vis spectra. Polymer P‐1 , terpyridine‐bearing poly(triphenylamine‐alt‐fluorene) with a high fluorescence quantum yield (62%) shows much higher sensitivities toward Fe³⁺, Ni²⁺, and Cu²⁺ as compared with the other metal ions investigated. Especially, Fe³⁺ can lead to an almost complete fluorescence quenching of polymer P‐1 . Whereas, the analogous polymer P‐2 , in which N‐ethylcarbazole repeat units replace the fluorene units in P‐1 , shows a very poor selectivity. It demonstrates that polymers with a same receptor may show different sensitivity to analytes owing to their different type of backbones. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1310–1316, 2010     

Luminescent heptadentate Tb complex with pendant aza-15-crown-5 showing recognition of lactate and salicylate in aqueous solution

The coordinatedly unsaturated neutral complex TbL1 that possesses two labile metal-bound water molecules provides linear response to lactate in the range of 0-3.0 mM at the simulated extracellular background with the variations of Tb luminescence lifetime as output; the maximal amplification of the luminescence intensity of TbL1 reaches a factor of 135 upon titration with aromatic antenna salicylate in the physiological pH window.     

Fluorescent conjugated polymers for chemical and biochemical sensing

This review deals with the emerging field of fluorescent conjugated polymers for the development of chemical and/or biochemical sensors. As a result of their amplified physical properties due to a “molecular wire effect”, these materials offer excellent characteristics to develop different sensing schemes (e.g., employing direct superquenching or relying on development of fluorescence-resonance-energy-transfer formats). The versatility of their synthesis procedures allows us to introduce the desired functional groups to achieve analytically useful interactions with analytes [e.g., from transition-metal ions to explosives, or even, in recent years, relevant biomolecules (e.g., proteins or DNA, where conformational changes play a decisive role in detection)].     

Synthesis and electroluminescence properties of carbazole-containing 2,6-naphthalene-based conjugated polymers

Three types of carbazole containing 1,5-disubstituted poly(2,6-naphthalene) derivatives, i.e., 2,6-naphthalene homopolymer that has a carbazolyl side chain at 1,5-positions, random copolymers and alternating copolymers consisting of 1,5-dialkoxynaphthalene-2,6-diyl and N-phenylcarbazole-2,7-diyl were newly synthesized by Ni-mediated Yamamoto polycondensation and Pd-catalyzed Suzuki coupling reaction. The number-average molecular weights (M_n) of the polymers and their polydispersity indices (M_w/M_n) were 5.4-8.2 × 10³ and 1.4-1.7, respectively. These polymers exhibited blue photoluminescence in the film states and high fluorescence quantum efficiencies in CHCl₃ (?_fl = 0.70-1.00). The electroluminescence properties of these polymers were investigated by fabricating a PLED device that has a configuration of ITO/PEDOT(PSS)/polymer/CsF/Al. The device fabricated with the random copolymer exhibited highest performances showing a maximum brightness of 8370 cd/m² at 13 V and a maximum efficiency of 2.16 cd/A at 7 V.     

含苯并氮杂15-冠-5侧基的线型聚硅氧烷促进液膜离子传输性能

N-十一碳烯和N-烯丙基苯并氮杂15-冠-5和甲基二氯硅烷硅氢加成后, 再与端羟基聚二甲基硅氧烷反应, 用三甲基氯硅烷封端, 合成了两种含苯并氮杂15-冠-5侧基的线型聚硅氧烷。分别以两种聚合物为液膜离子传输载体, 研究了载体种类、阴离子、阳离子种类及载体浓度和盐浓度对离子传输速率的影响, 并考察了膜的稳定性。     

Synthesis and properties of novel heat-resistant fluorescent conjugated polymers with bisindolylmaleimide

Novel conjugated polymers with bisindolymaleimide were synthesized via simple metal-free condensation polymerization. The polymers exhibited high glass transition temperatures and decomposition temperatures with considerable luminescent properties.     

Fluorescence quenching of conjugated polymer by coupling plasmonic silver nanocap array

The optical properties of poly(2,5-dioctyloxy-p-phenylene) (DOO-PPP) coupled to a silver nanocap array are investigated by Raman and photoluminescence spectra. The emission intensity of the DOO-PPP coupled to the silver nanocap array is much weaker than that of the DOO-PPP film due to the fluorescence quenching of the silver nanocap array. In contrast with the freshly prepared sample, the fluorescence quenching efficiency of the silver nanocap array is obviously decreased for the sample exposed in air; correspondingly, the Raman intensity at 1609 cm⁻¹ is markedly decreased, which is characteristic Raman peak of the inter-ring CC stretching vibration in the conjugated polymer. The experimental results indicate that the inter-ring CC stretching vibration plays an important role for the fluorescence quenching in the DOO-PPP coupled to the silver nanocap array.     

Cationic conjugated polymers as signal reporter for label-free assay based on targets-mediated aggregation of perylene diimide quencher

Herein, we reported a cationic conjugated polymers-based new biosensor with label-free and fluorescence turn-on strategy by virtue of targets regulated aggregation and quenching ability of perylene diimide derivatives.     

A rapid Hg sensor based on aza-15-crown-5 ether functionalized 1,8-naphthalimide

A new 1,8-naphthalimide derivative bearing an aza-15-crown-5 macrocycle (1) has been synthesized as a chemosensor for Hg²⁺ by a two-step reaction. The sensor shows selectivity to Hg²⁺ over 11 other metal cations in aqueous media. Upon addition of Hg²⁺, the fluorescence emission of the sensor at 537 nm is significantly quenched along with 22 nm blue-shift that makes this compound a useful sensor for Hg²⁺ measurement.     

Synthesis and electroluminescent performance of thermally activated delayed fluorescence‐conjugated polymers with simple formylphenyl as pendant acceptor

Formylphenyl has been demonstrated to act as an acceptor to construct thermally activated delayed fluorescence (TADF) emitter, and therefore a series of the TADF‐conjugated polymers with formylphenyl as pendant acceptor and carbazole/acridine as backbone donor are designed and synthesized. All polymers involve the twisted donor/acceptor structural moieties with the sufficiently spatial separation between the highest occupied molecular orbital and the lowest unoccupied molecular orbital as well as a small singlet/triplet splitting, and exhibit the legible TADF features confirmed by theoretical calculation and their transient decay spectra. The solution‐processed organic light‐emitting diodes using neat film of the polymers as emissive layer achieve excellent performance with the maximum external quantum efficiency (EQE) of up to 10.6%, the maximum current efficiency of up to 35.3 cd A⁻¹ and the low turn‐on voltage of 2.7 V. Moreover, the EQE still remains 10.3% at the luminance of 1000 cd m⁻² with the low driving voltage of 4.4 V and extremely small efficiency roll‐off. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1989–1996     

Hyperbranched polymers with maleic functional groups as radical crosslinkers

The crosslinking performance of the unsaturated hyperbranched polyester poly(allyloxy maleic acid‐co‐maleic anhydride) (MAHP) was investigated with copolymerizations of three different monomers: styrene, vinyl acetate, and methyl methacrylate. Both styrene and vinyl acetate afforded interpenetrating‐polymer‐network copolymer gels. The gels exhibited crosslink density gradients through the polymer matrices on a macroscopic level, and density maximums were concentrated around the MAHP moieties. The heterogeneity of the gels is briefly discussed in terms of a modified two‐phase model, where one phase consists of an elastic part of low crosslinking density and the other phase consists of an inelastic dendritic part with a highly condensed bond density. Unlike the two‐phase model developed by Choquet and Rietsch, the modified two‐phase model takes into account that both phases swell in good solvents. Unlike copolymerizations employing styrene or vinyl acetate, the copolymerization of MAHP with methyl methacrylate afforded noncrosslinked starbranched copolymers that consisted of a MAHP core from which long poly(methyl methacrylate) branches were protruding. The different behaviors of the copolymerizations of the three monomers used in this study can rationally be explained by their different reactivity ratios with maleic end groups of MAHP. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 964–972, 2001     

Synthesis and photophysical properties of a 2,2′-bianthracene-based receptor bearing two aza-15-crown-5 ethers for naked-eye detection of barium ion

As a novel chromofluorophore, 9,9′-dimethyl-2,2′-bianthracene 3 has been successfully synthesized by reductive coupling of 2-chloro-9-methylanthracene. Absorbance and fluorescence maxima of 3 can be shifted to visible-region comparing to the former 2,2′-binaphthyl-based receptors. Receptor 2 bearing aza-15-crown-5 moieties via methylene spacer provides selective UV-vis and fluorescence responses for Ba²⁺ due to the restriction of the conformational change through the formation of an intramolecular sandwich-complex by two azacrown ethers, resulting in the presence of Ba²⁺ that can be detected by naked eye in aqueous acetonitrile.     

Zn selective luminescent ‘off-on’ probes derived from diaryl oxadiazole and aza-15-crown-5

New photo-induced electron transfer (PET) probes OMOX and OBOX, carrying an additional binding site in the form of ‘oxadiazole nitrogen’ have been designed to evaluate binding interactions with biologically significant Li⁺, Na⁺, K⁺, Ca²⁺, Mg²⁺, and Zn²⁺ including environmentally toxic Ba²⁺ and Cd²⁺ using optical spectral techniques. While Li⁺, Na⁺, and K⁺ did not appreciably perturb either the absorption or emission spectra, Ba²⁺, Ca²⁺, Mg²⁺, Zn²⁺, and Cd²⁺ induced slight red shifts (2-8 nm) in the UV-visible spectra as well as pronounced chelation induced enhanced fluorescence (CHEF). Both OMOX and OBOX exhibited the highest CHEF in contact with the zinc ion, whereas Ba²⁺, Ca²⁺, Mg²⁺, and Cd²⁺ induced relatively less emission enhancements. OBOX, which is a poorer emitter (Φ_f=0.0062) than OMOX (Φ_f=0.015), showed highly promising 160-fold emission enhancement in the presence of Zn²⁺. Potential, therefore is available in OBOX to function as a selective luminescent ‘off-on’ sensor for Zn²⁺ in the presence of coordinatively competing Ba²⁺, Ca²⁺, Mg²⁺, and Cd²⁺ ions.     

Spectrophotometric investigation of the complex formation between aza-15-crown-5 containing chromoionophores and alkali and alkaline earth metal ions in acetonitrile

Complexation of two cationic styryl dyes containing aza-15-crown-5 moiety and Na(+), K(+), Ca(2+) and Ba(2+) was investigated spectrophotometrically in water-containing acetonitrile medium. The ligand/complex ratio was estimated using a method for resolution of overlapping bands. A model for evaluation of the water action is proposed and stability constants were calculated for all metal ions in question.     

A highly fluorescent adenine derivative and its interaction with iron ions

In this paper, an adenine-derived fluorescent chromophore (HCC-APA) was synthesized to detect its interaction with iron ions. The results showed that a large stokes shift (υ = 10981.5 cm^?1) fluorescence of the HCC-APA was appeared. The fluorescence quantum yields of HCC-APA in DMF and THF were 3.49% and 17.54%, respectively, demonstrating its higher fluorescence performance than unmodified adenine. Besides, the fluorescence quenching of HCC-APA with iron ions was further detected. Fluorescence titration experiments confirmed that the detection limit of HCC-APA for Fe³⁺ was 3.69 μM. The interaction between iron ions and HCC-APA was investigated by continuous variable method, indicating that the binding ratio is 1:1. And the interaction site was deeply explored by ¹H NMR and molecular simulation.     

Synthesis of conjugated polymers with pendant ruthenium terpyridine trithiocyanato complexes and their applications in heterojunction photovoltaic cells

Two conjugated polymers based on poly(phenylenethiophene) and poly (fluorenethiophene) main chain functionalized with pendant trithiocyanato ruthenium terpyridine complexes were synthesized by the Suzuki coupling reaction. The ruthenium complexes can extend the absorption band to longer wavelength and enhance the photosensitivity in this region. The polymers exhibit very broad absorption band spanning from 400 to 750 nm due to the presence of π‐conjugated system and the ruthenium complexes. Such enhancement in optical absorption enables the utilization of solar light in the near IR region. By space charge limited current modeling, the hole carrier mobilities of the polymers were calculated to be in the order of 10^?4 cm² V^?1 s^?1, which greatly facilitate the transport of charges after the separation of excitons. Heterojunction photovoltaic cells with simple structure ITO/polymer/C₆₀/Al were fabricated. Under simulated AM1.5 solar light illumination, the short circuit currents, open circuit voltages, and power conversion efficiencies of the photovoltaic cells were measured to be 1.53–2.58 mA cm^?2, 0.12–0.24 V, and 0.084–0.12%, respectively. Deposition of PEDOT:PSS on ITO surface did not show significant difference in device performance. Plot of incident photon to charge efficiency as the function of wavelength suggests that absorption by both conjugated main chain and ruthenium complex are essential to the photocurrent generation. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1305–1317, 2008     

Synthesis and characterization of organometallic conjugated polymers containing tricarbonyl(arene)chromium unit and platinum

Novel organometallic conjugated polymer containing (η⁶-arene)Cr(CO)₃ and platinum in the main chain was synthesized by dehydrohalogenation coupling reaction of (η⁶-1,4-diethynylbenzene)tricarbonylchromium with trans-(PBu₃)₂PtCl₂. The polymer was soluble in common organic solvents and has the number-average molecular weight of 31,000 by GPC analysis. The polymer exhibited an absorption peak derived from π-π^∗ interaction at 358 nm in the UV-Vis spectrum, which showed a red shift of approximately 90 nm compared to that of the model compound. The photochemical ligand exchange reaction of the polymer was also investigated.     

Highly sensitive detection of nitroaromatic explosives using an electrospun nanofibrous sensor based on a novel fluorescent conjugated polymer

An electrospun nanofibrous explosive sensor was first constructed based on a newly developed fluorescent conjugated polymer P containing heteroatom polycyclic units. Electrospinning by doping polymer P as a fluorescent probe in a polystyrene supporting matrix afforded a fluorescence nanofibrous film with unique porous structures, and effectively avoided the aggregation of polymer P. The novel explosive sensor exhibited stable fluorescence property, satisfactory reversibility with less than 5% loss of signal intensity after four quenching–regeneration cycles, and good reproducibility among three batches with a relative standard deviation of 2.8%. Such fabricated sensor also showed remarkable sensitivity toward a series of trace nitroaromatic explosive vapors, including picric acid (parts-per-trillion level) and 2,4,6-trinitrotoluene vapor (parts-per-billion level), as well as good selectivity with less than 10% response to typical interferents. Therefore, the present strategy extends the application of different kinds of conjugated polymers for the construction of optical chemosensors.