Luminescent Polymers Research Articles

Highly efficient and selective detection of sulfur ions and picric acid through salamo-Cd(II) coordination polymer chemosensor

A salamo-Cd(II) coordination polymer [Cd(HL)2(4,4ʹ-bipy)]n (CP-Cd(II)) was synthesized by introducing a auxiliary ligand 4,4ʹ-bipy to the host ligand H2L (4-chloro-4ʹ-bromo-6-bromo-6ʹ-tert-butyl-2,2ʹ-[ethylenedioxybis(nitrilomethylidyne)]di-phenol), and used as a fluorescent chemical sensor to detect sulfur ions (S2−) and picric acid (PA). Single crystal X-ray analysis demonstrated that the Cd(II) atom has a slightly distorted hexa-coordinate octahedron configuration and forms an infinite one-dimensional chain structure due to the intervention strategy of the auxiliary ligand. In fluorescence method, the sensor CP-Cd(II) exhibits good selectivity and sensitivity for S2− and PA with fluorescence turn-on and off effects sequentially. Additionally, the quenching efficiency of PA remains unchanged even after the sensor has been used for four cycles. At the same time, the sensor CP-Cd(II) can quickly detect S2− and PA within 10 s, which make them charming, recoverable and reliable luminescent coordination polymer sensor materials for detecting S2− and PA. The sensing mechanisms were attentively explored by mass spectrometry analysis, spectroscopic studies and density functional theory (DFT) calculations. Furthermore, the potential application of the sensor for further detection of S2− ions and PA in environmental systems was studied through actual water sample detection.

Thermal/Redox-triggered release of pyrazinic functional molecules by coordination polymers with luminescence monitoring ability

Storage of volatile active molecules, along with the prolongation of their specific functions, requires the use of regulatable carriers. Pyrazine derivatives are highly volatile compounds with a broad application owing to their flavoring, pharmaceutical, antimicrobial, antiseptic, and insecticidal properties. In this study, pyrazines were stored by coordinating them with cuprous iodide to easily generate a series of luminescent coordination polymer (CP)-based carriers. The CPs could respond to thermal-redox stimuli and manipulate pyrazine release by breaking the labile Cu–N bonds when triggered by the two stimuli. Moreover, the release process could be visualized by decreased luminescence caused by the gradual decomposition of CP structures. The loading efficiencies ranged from 31% to 38%, and the controlled release behaviors accord with the zero-order kinetics. This work is the first to prove that CPs could function as dual stimuli-mediated delivery systems, which hold the potential to control the release and strengthen the usability of functional molecules.

Special Features of Multiple Luminescence of the Dyad Containing Imidazole and Coumarin Fragments in Photocured Network Acrylate Polymers

The conditions to prepare luminescent acrylate polymers containing the organic dyad, molecule of which combines two different emitting fragments, hydroxyl-substituted 2,4,5–triarylimidazole and 8-azomethine-7-hydroxycoumarine moieties, via photocuring have been optimized. The effect of the nature of the photocured network acrylate polymers on luminescent properties of the dyad has been investigated. The prepared aliphatic network polymers have exhibited independent fluorescence of both molecule fragments, dependent on the excitation wavelength. At the same time, the aromatic network polymers and the aliphatic network polymers containing ether links have revealed only the imidazole fragment fluorescence. The fluorescence nature has been stronger dependent on the polymer repeat unit structure and the content of the aromatic fragments in the polymer matrix than on the presence of the hydroxyl groups in the polymer. It has been shown that the emission of the imidazole fragment of the dyad in the aliphatic network polymers depends on the internode distance and conditional polarity of the medium.

Stimuli-Responsive π-Conjugated Polymers Showing Solid-State Emission Based on Boron-Fused Azomethine Complexes with NNO-Tridentate Ligands.

We report stimuli-responsive luminescent π-conjugated polymers involving the boron-fused azomethine (BAm) structure with the NNO-tridentate ligands and demonstrate their application to film-type sensors. The acid-responsive properties of the polymers are provided by the free lone-pair electrons of the nitrogen atom on the BAm unit. The polymer films showed red shifts in emission wavelengths under acid vapor, and the responses were reversible and corresponded to deprotonation. Furthermore, owing to environmental sensitivity in the film state, unique luminescent color changes were observed. The bilayer films of the BAm polymer coated by poly(n-butyl methacrylate) exhibited vapochromic luminescence with gradual blue shifts (orange → yellow → green) by vapor annealing with chloroform depending on the exposure time. We demonstrated that these changes were applicable for evaluating solvent-vapor permeability of target membranes. This study shows that nitrogen substitution into existing organic compounds is effective for creating stimuli-responsive materials.

Rapid detection of nanoplastic particles by a luminescent Tb-based coordination polymer

Nanoplastics (NPs) in aqueous environment have become a category of emerging pollutants on account of their potential risks to both human health and environment. The detection of NPs is a great challenge due to the lack of sensitive and selective sensing materials with fast response time and wide sensing range of particle sizes. Herein, a Tb-based coordination polymer has been synthesized for luminescent detection of nanopolystyrene with different particle sizes in aqueous solutions, showing a low limit of detection, fast response time within 10 s and high selectivity in the presence of other plastics. The “turn-on” sensing mechanism is studied in detail. This work provides a facile method for the fast detection of NPs.

High efficiency luminescent polystrene beads with a novel europium phenanthrene diketonate

Fluorescent or luminescent polymer particles (beads) have become an important tool in bioanalytical and other applications, the size regime of interest ranging from some ten to a few hundred nanometers. Bead-imbedded rare earth complexes are of particular interest, which is owed to their narrow line emissions, large separation between excitation and emissions (apparent Stokes shifts) and extrordinarily longs decay times of the emission. The latter is advantageous for the discrimination against undesired background (e.g. autofluorescence) via time gated analysis; high quantum yields and high absorptions of the incident radiation at the same time are dominant optical criteria. We here describe and characterize a new Eu3+ diketonate comprising tris(3-phenanthryl-3,3,3-trifluoroacetone)Eu(III)-di(tri-n-octyl phosphine oxide), Eu(pta)3(TOPO)2, in polystyrene with high quantum efficiencies (up to 90%) and long decay times (up to 680 μs).

Characterization of carbon quantum dots obtained through citric acid pyrolysis

Carbon quantum dots (CQDs) were produced through citric acid (CA) pyrolysis. For the first time, we searched for the optimum CA pyrolysis duration and temperature. As a basic quality criterion of quantum dots, photoluminescence quantum yield (QY) was chosen. For this purpose, the pyrolysis products were analysed with UV–Vis spectroscopy and fluorescence (FL) spectroscopy. The optimum pyrolysis time was accepted to be 240 min, whereas the optimum pyrolysis temperature was approved as 200 °C. The pyrolysis products obtained at the optimum conditions were further subjected to dialysis. Finally, the purified CQDs were characterised with FL spectroscopy, transmission electron microscopy, dynamic light scattering, Raman spectroscopy, and Fourier transform infra-red spectroscopy. The produced CQDs were shown to be stable in water solution. Their PL QY (6.1%) was decreased to 1.2% after CQDs exposure to daylight for 90 days. Luminescent polymer composites were produced when CQDs were embedded in the poly(vinyl alcohol) and bacterial cellulose matrices. The prepared composites can be used for fabrication of transparent, flexible, and luminescent films and for production of anti-counterfeiting paper for confidential documents, labels, and banknotes.

Stimuli-Responsive Self-Healing Luminescent Materials Based on Lanthanide Ions and Bipyridine Moieties

Contemporary, luminescent materials possessing rapid stimulus-responsive characteristics demonstrate considerable potential in anti-counterfeiting applications. However, if anti-counterfeiting materials become damaged during use, the integrity of the information will be compromised. Consequently, endowing materials with self-healing ability can ensure the accuracy and integrity of anti-counterfeiting data. In this study, a luminescent metallo-supramolecular polymer is synthesized through the coordination of lanthanide ions (Ln3+) and bipyridine ligands within polyurethane (PU) chains. The PU elastomers created using 4,4′-dicyclohexylmethane diisocyanate display remarkable transmittance and hydrophobic properties following coordination with Ln3+. The dynamic Ln–N coordination imparts self-healing behavior and robust mechanical performance to the PU elastomers. The “antenna effect” imbues the resulting materials with exemplary luminescent properties, and the emission color can be conveniently modulated by adjusting the Eu3+/Tb3+ ratio. Importantly, all luminescent materials exhibit a rapid stimulus-response to acid-base fluctuations through the disruption or restoration of the “antenna effect” between Ln3+ and bipyridine, a critical aspect for the advancement of materials in the anti-counterfeiting and information encryption domains.

Turning the energy channel of side-chain TADF polymers by monomer optimization for high-efficiency solution-processed white OLEDs

Suppressing non-radiative channel in luminescent polymer is the key factor for high device efficiency of organic light-emitting diodes (OLEDs). In this paper, we synthesized three side-chain TADF polymers, PTRZ-TRZ, PTRZ-TPA and PTRZ-Cz, to deeply investigate the relationship between energy transfer and molecular structure. The photophysical measurements show that the copolymerized monomer has significant effect on the exciton deexcitation process of TADF fragment. The rigid carbazole unit can efficiently separate the TADF units to inhibit the aggregation-caused quenching (ACQ) of polymer, while electron-donating triphenylamine unit will induce the severe charge transfer state to form low energy exciplex, which lead to severe energy leakage of the excited TADF. Moreover, according to the single-charge devices test, the ideal separation unit also can improve the capability of charge injection and carrier balance. As a result, the solution-processed OLEDs host with PTRZ-Cz achieved the external quantum efficiency (EQEmax) of 14.2%, which was much higher than that of PTRZ-TPA and PTRZ-TRZ. By doping red phosphorescent emitter Ir(MDQ)2(acac), the hybrid white OLED devices (T-P WOLEDs) based on PTRZ-Cz achieved the maximum current efficiency (CEmax), power efficiency (PEmax) and EQEmax of 46.8 cd/A, 32.6 lm/W and 20.7%, respectively, with a high CRI of 80.6. The outcomes obtained in this study can provide useful insights into the structure−property relationship for further development of efficient TADF polymer hosts for solution-processable OLEDs.

Color-Shifting Fluorescent System Based on an AIE Polymer with an Upper Critical Solution Temperature

The design of thermoresponsive luminescent polymers with both a tunable upper critical solution temperature (UCST) and a tunable color is of great challenge. Herein, a series of thermoresponsive copolymers with UCST and aggregation-induced emission (AIE) behaviors are prepared, and a color-shifting fluorescent system based on the energy conversion between the AIE polymers and fluorescent dyes is constructed. The copolymers are prepared from acrylamide and 6-(4-vinylphenyl)-2,4-diamino-1,3,5-triazine (VPhDT). Benefitting from VPhDT, an AIE-active monomer that can provide multiple hydrogen bonds and enhance association of the polymer chains, the obtained copolymers exhibit both UCST and AIE behaviors in aqueous solutions. Utilizing the AIE copolymers as the donor and fluorescent dyes as the acceptors, color-shifting fluorescent systems that can emit blue, green, and red lights are established. The color-shifting fluorescent systems also exhibit tunable luminescent intensities and colors with the stimuli of temperature and pH. Such a color-shifting fluorescent system may have promising applications in the fields of temperature sensors and information displays.

From Glow to Growth: Chemiluminescence Induced Cationic Polymerization Using Ferrocenium Salt

AbstractChemiluminescence (CL) has recently emerged as a novel light source for triggering various photoreactions with appealing features such as the elimination of continuous power supply and complex instrumentation. Here, CL‐induced cationic photopolymerization using ferrocenium salts as unimolecular photoinitiators is reported. The ferrocenium salts, facilely synthesized via ligand exchange reactions, absorb the visible light emitted from CL reactions and generate Lewis acids capable of initiating the cationic polymerization of oxirane and vinyl monomers. The presented method can be applied to create linear polymer chains and cross‐linked luminescent polymer networks, which have significant potential in the fabrication of new polymeric materials and various bioapplications.

Synthesis and Characterization of Novel Non-conjugated hyperbranched polysiloxanes with AIE Effect

To obtain unconjugated hyperbranched polysiloxane (HBPSi), the triethoxyvinylsilane (A-151) and simple polyol compounds were used as raw materials, and two kinds of unconjugated HBPSi which the terminal group is -OH group and C=C bond were synthesized via a simply transesterification condensation, and the factors that affecting their luminescence are also further discussed. The results showed that, both of these two HBPSi exhibits excellent aggregate induced emission effect. The structure rich in π electrons or lone pair electrons in the raw materials basically maintains its original state in the polymer, and the spatial conjugation of the two leads to the luminescence of non-conjugated polymers. A large number of -OH groups in the polymer can form hydrogen bonds, and the promotion of hydrogen bonds makes the target products further gather spontaneously, which further enhances the spatial conjugation and improves the rigidity of the molecules. It can be concluded that under certain conditions, the larger steric hindrance of the molecule itself will affect the polymerization degree of the final product and the aggregation degree of the polymer molecule, while low polymerization and aggregation degree will result in higher energy required for the material to fluoresce. This study provides some reference significance for the preparation of non-conjugated luminescent materials with higher fluorescence intensity.

Design, Synthesis, and Biomedical Application of Multifunctional Fluorescent Polymer Nanomaterials.

Luminescent polymer nanomaterials not only have the characteristics of various types of luminescent functional materials and a wide range of applications, but also have the characteristics of good biocompatibility and easy functionalization of polymer nanomaterials. They are widely used in biomedical fields such as bioimaging, biosensing, and drug delivery. Designing and constructing new controllable synthesis methods for multifunctional fluorescent polymer nanomaterials with good water solubility and excellent biocompatibility is of great significance. Exploring efficient functionalization methods for luminescent materials is still one of the core issues in the design and development of new fluorescent materials. With this in mind, this review first introduces the structures, properties, and synthetic methods regarding fluorescent polymeric nanomaterials. Then, the functionalization strategies of fluorescent polymer nanomaterials are summarized. In addition, the research progress of multifunctional fluorescent polymer nanomaterials for bioimaging is also discussed. Finally, the synthesis, development, and application fields of fluorescent polymeric nanomaterials, as well as the challenges and opportunities of structure-property correlations, are comprehensively summarized and the corresponding perspectives are well illustrated.

Synthesis, Structure, and Spectroscopic Properties of Luminescent Coordination Polymers Based on the 2,5-Dimethoxyterephthalate Linker

We report on the synthesis and the crystal structure of the solvent-free coordination polymer CoII(2,5-DMT) (1) with 2,5-DMT ≡ 2,5-dimethoxyterephthalate which is isostructural to the already reported MnII and ZnII congeners (C2/c, Z = 4). In contrast, for M = MgII, a MOF with DMF-filled pores is obtained, namely Mg2(2,5-DMT)2(DMF)2 (2) (P1¯, Z = 2). Attempts to remove these solvent molecules to record a gas sorption isotherm did not lead to meaningful results. In a comparative study, the thermal (DSC/TGA) and luminescence properties of all the four compounds were investigated. The compounds of the MII(2,5-DMT) composition show high thermal stability up to more than 300 °C, with the ZnII compound having the lowest decomposition temperature. MII(2,5-DMT) with MII = MnII, ZnII and 2 show a bright luminescence upon blue light irradiation (λ = 405 nm), whereas CoII in 1 quenches the emission. While ZnII in ZnII(2,5-DMT) and MgII in 2 do not significantly influence the (blue) emission and excitation bands compared to the free 2,5-DMT ligand, MnII in MnII(2,5-DMT) shows an additional metal-centred red emission.

Tuning the Thermometric Features in 1D Luminescent EuIII and TbIII Coordination Polymers through Different Bridge Phosphine Oxide Ligands.

TbIII and EuIII systems have been investigated as ratiometric luminescent temperature probes in luminescent coordination polymers due to TbIII → EuIII energy transfer (ET). To help understand how ion-ion separation, chain conformation as well as excitation channel impact their thermometric properties, herein, [Eu(tfaa)3(μ-L)Tb(tfaa)3]n one-dimensional (1D) coordination polymers (tfaa- = trifluoroacetylacetonate, and L = [(diphenylphosphoryl)R](diphenyl)phosphine oxide, R = ethyl - dppeo - or butyl - dppbo) were synthesized. The short μ-dppeo bridge ligand leads to a more linear 1D polymeric chain, while the longer μ-dppbo bridge leads to tighter packed chains. As the temperature rises from 80 K, upon direct TbIII excitation at 488 nm, the TbIII emission intensity decreases, while the EuIII emission intensity increases after 160 and 200 K when L = dppeo or dppbo, respectively. The temperature-dependent emission intensities, due to TbIII → EuIII ET, enable the development of ratiometric luminescent temperature probes featuring maximum relative thermal sensitivity up to 3.8% K-1 (250 K, L = dppbo, excitation at 488 nm). On the other hand, the same system displays maximum thermal sensitivity up to 3.5% K-1 (323 K) upon ligand excitation at 300 nm. Thus, by changing the excitation channel and bridge ligand that leads to modification of the polymer conformations, the maximum relative thermal sensitivity can be tuned.

Regulating Circularly Polarized Luminescent Behavior of Luminescent Liquid Crystalline Polymers through Resonance Energy Transfer

Regulating Circularly Polarized Luminescent Behavior of Luminescent Liquid Crystalline Polymers through Resonance Energy Transfer

A novel thiazole-based luminescent porous organic polymer as recyclable and selective turn-off fluorescent sensor for ultrasensitive detection of Pd2+

A novel thiazole-based luminescent porous organic polymer as recyclable and selective turn-off fluorescent sensor for ultrasensitive detection of Pd2+

Detecting phosphate using lysine-sensitized terbium coordination polymer nanoparticles as ratiometric luminescence probes.

Probes for detecting phosphate ions (Pi) are required for environmental monitoring and to protect human health. Here, novel ratiometric luminescent lanthanide coordination polymer nanoparticles (CPNs) were successfully prepared and used to selectively and sensitively detect Pi. The nanoparticles were prepared from adenosine monophosphate (AMP) and Tb3+, and lysine (Lys) was used as a sensitizer (through the antenna effect) to switch on Tb3+ luminescence at 488 and 544nm while Lys luminescence at 375nm was quenched because of energy transfer from Lys to Tb3+. The complex involved is here labeled AMP-Tb/Lys. Pi destroyed the AMP-Tb/Lys CPNs and therefore decreased the AMP-Tb/Lys luminescence intensity at 544nm and increased the luminescence intensity at 375nm at an excitation wavelength of 290nm, meaning ratiometric luminescence detection was possible. The ratio between the luminescence intensities at 544 and 375nm (I544/I375) was strongly associated with the Pi concentration between 0.1 and 6.0μM, and the detection limit was 0.08μM. The dual-emission reverse-change ratio luminescence sensing method can exclude environmental effects, so the proposed assay was found to be very selective. The method was successfully used to detect Pi in real water samples, and acceptable recoveries were found, suggesting that the method could be used in practice to detect Pi in water samples.

Structural metamorphosis and photophysical properties of thermostable nano- and microcrystalline lanthanide polymer with flexible coordination chains

ABSTRACT Luminescent lanthanide coordination polymer crystals (LCPCs) represent an area of growing interest in materials chemistry owing to their unique and tailorable functional properties. The LCPCs provide a high level of structural tunability, including size- and morphology-dependent properties; therefore, they are promising materials for next-generation phosphors in a wide range of applications such as light emitting diodes. Here, by controlling the morphology of thermostable europium coordination polymer crystals, [Eu(hfa)3(dpbp)]n, hfa: hexafluoroacetylacetonate and dpbp:4,4’-bis(diphenyl phosphoryl) biphenyl), we realized a novel red phosphor with narrow linewidth emission (FWHM = 7.8 nm). The obtained luminescent LCPCs with unique structures were characterized by X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), dynamic light scattering (DLS) and thermogravimetric analysis. Among, them, size tunable crystalline polymer spheres were found to have high internal quantum efficiency (ex., IQE = 79%) and highly thermostability (>300°C), and to exhibit dispersibility in PMMA media. The obtained results on the structural tunability of these materials can be used for the development of synthesis techniques for nanoscale materials based on crystalline lanthanide-based coordination phosphors.

Tenon effects at drilled multi-walled carbon nanotubes to strongly enhance mechanical and luminescent properties of epoxy resin composites

The effectiveness of mechanical enhancement of carbon nanotubes-polymer matrices, particularly, epoxy resin (EP), depends strongly on the interface interaction between constituents. Providing rough surface and chemical activity of CNTs is the effective way to reach that. To explore both approaches, in this study, unzipped CNTs (uCNTs) and drilled CNTs (dCNTs)were prepared by Hummers methods and chemical etching. The structure of uCNTs and dCNTs were characterized by FT-IR, TG and XPS. The Eu3+ complexes were anchored to CNTs, uCNTs, and dCNTs via strong interaction to form a stable “tenon” structure. That materials were found useful to fabricate the composite with EP. Our study reveals that the ultimate tensile and flexural strengths of Eu-dCNTs/EP increases by 161% and 226%, indicating that Eu-dCNTs improves significantly the mechanical properties of EP. The drilling treatment and the “tenon” structure of the Eu-dCNTs hybrid play a key role in improving the mechanical properties of EP. Fracture morphology and the strengthening mechanism were discussed. Our study shows an effectiveness of using dCNTs and uCNTs to fabricate luminescent polymer composites with enhanced properties.