Luminescent Polymers Research Articles

Two Cd-Based Luminescent Coordination Polymers Constructed from a Truncated Linker.

Two cadmium coordination polymers, WSU-30 and WSU-31, were synthesized through solvothermal methods by using the low-symmetry TPE-based linker m-H4ETTC. The m-H4ETTC linker and both coordination polymers were fully characterized by using single-crystal X-ray diffraction, infrared spectroscopy, and photoluminescent emission spectroscopy. Structural analysis of WSU-30 and WSU-31 showed that each compound contains previously unknown tetranuclear cadmium(II) secondary building units. The topological analysis revealed that the 4,8-connected net of WSU-30 contains the underlying topology, alb-4,8-P21/c-1, while the mixed linker WSU-31 possesses a 3,10-connected net known as 3,10T31 topology. If the m-ETTC linker is considered as two 3-connected nodes, WSU-30 possesses a very rare 3,3,8-connected 3,3,8T25 topology, and WSU-31 possesses a previously unknown 3,12-connected net, named 3,12T61.

Dual Luminescent Coordination Polymers Based on Flexible Aliphatic Carboxylate Ligands Supplementing by Rigid Bipyridyl Ligands for 2,4-Dinitrophenol (DNP) and Iron (III) Ion Detections

Based on flexible aliphatic carboxylate ligands supplementing by isomerized structure of rigid bipyridyl ligands, three novel Zn(II) coordination polymers, namely Zn 2 (dpe)(glutarate) 2 (H 2 O) 2 (1), Zn 2 (glutarate) 2 (tdpe) 2 (H 2 O) 2 (2), and Zn(H 2 O)(succinate)(tdpe) 2 (3) (dpe = 1,2-di(4-pyridyl)ethylene, tdpe = trans-1-(2-pyridyl)-2-(4-pyridyl)ethylene)), have been synthesized by appropriate methods. The crystallographic data of all complexes presented the diverse geometries of Zn(II) center such as two independent of square pyramidal and tetrahedral (in (1)), trigonal bipyramidal (in (2)), and octahedral (in (3)). Both the carboxylate ligands act as bridging ligands with the various coordination mode to build up the main structures. While bipyridyl ligand showed only 4-pyridyl site in coordination bond with metal center providing only dpe acted as bridging ligand to build up the principal framework in (1). Whereas tdpe ligand presented monodentate coordination mode in the other. All structures of complexes indicated that the coexistence of two ligand types could support the higher dimensionality in the complexes. Complex 1 was further used as nitro-aromatic compounds (NACs) and heavy metal ion sensors. It shows highly sensitive and selective sensing to 2,4-dinitrophenol (DNP), and Fe(III) ion, respectively based on fluorescence quenching effect.

Luminescent detecting of Fe3+ and Cr2O72− ions by three ternary 2D coordination polymers

To investigate the effects of central metal ions on the structures and luminescent sensing properties of ternary luminescent coordination polymers, three new complexes, {[Co(L)(TBTA)(H2O)2]·H2O}n (1), {[Zn(L)(TBTA)]·1.9H2O}n (2) and [Cd(L)(TBTA)]n (3) (L = 1,4-bis(5,6-dimethylbenzimidazol-1-yl)-2-butylene, H2TBTA = tetrabromoterephthalic acid), were synthesized and characterized. 1 and 3 reveal a sql layer, whereas 2 displays a hcb network. Three compounds can be used as probes for the sensitive sensing of Fe3+ and Cr2O72− ions by a luminescence quenching process. The limits of detection (LOD) of 1, 2 and 3 for the detection of Fe3+ ions are 1.61, 1.13 and 0.71 μM, respectively, while the LOD for the sensing of Cr2O72− ions are 1.95, 2.31 and 1.84 μM, separately Possible mechanisms for the luminescence quenching process toward Fe3+ and Cr2O72− ions are presented. The central metal ions of the three ternary CPs play a key role for the effective detection of Fe3+ ions.

Stable 2D Zn(II) coordination polymer: selective detection of Fe3+ ion and treatment activity on psoriasis metabolic syndrome

ABSTRACT With the reaction between 1,3,5-tris(2-methylimidazol-1-yl)benzene (timb), a designed tripodal connector and Zn(NO3)2 · 6H2O in the presence of a hydroxyl functionalised carboxylate ligand isophthalic acid (OH-H2IPA), a novel luminescent coordination polymer (CP) containing Zn(II) ions as nodes was created through applying the reaction of solvothermal method, and its chemical formula is {[Zn5(timb)4(OH–IPA)4]·2NO3 · 2DMA·2H2O}n (1). Because of complex 1 excellent photoluminescence performances and water stability, it reveals the phenomenon of luminescence turn-off for the Fe3+ cation, and the value of Ksv is 9.59 × 103 M−1 (R2 = 0.9913). The application values of the new compound and its ligands on the psoriasis metabolic syndrome were finally evaluated.

Synthesis, structure and properties of luminescent Cd(II) coordination polymers based on imidazole-decorated tetraphenylethylene

Two new cadmium(II) luminescent coordination polymers (CPs), [Cd(L)Cl2]·3DMF (1) and [Cd(L)(DMA)(H2O](ClO4)2·5DMA (2) (L = 1,1,2,2-tetrakis(4-(1H-imidazol-1-yl)phenyl)ethene, DMF = N,N-dimethylformamide, DMA = N,N-dimethylacetamide), were synthesized under solvothermal conditions. Crystallographic analyses reveal that 1 and 2 have different two-dimensional (2 D) network structures. Both 1 and 2 show mechanochromic properties with fluorescent color change from blue to blue-green under UV light. In addition, 1 can be potentially utilized as mechanochromic material as well as a sensor for detection of DMF, exhibiting reversible mechanochromic luminescence with color changes and self-repairing behavior by grinding and soaking in DMF under UV irradiation. Furthermore, 1 can act as potential fluorescence materials for sensing Fe(III).

Supramolecular Engineering of Efficient Artificial Light-Harvesting Systems from Cyanovinylene Chromophores and Pillar[5]arene-Based Polymer Hosts.

Enhanced emission and adjustable wavelength for single luminogen systems are highly desirable in the scope of photoluminescent materials. Herein, a supramolecular strategy has been proposed for supramolecular assembly-induced enhanced emission and valid emission manipulation by fabricating an amphiphilic copolymer host material with pillar[5]arene units as the side chains, whereby cyanovinylene-based (CV) derivatives are anchored to the polymer hosts via host-guest interactions. The guest-bearing copolymers can further form luminescent supramolecular polymer nanoparticles (SPNs). Remarkably, the as-prepared SPNs exhibit dramatic emission enhancement and tunable fluorescence wavelength, ascribing to the synergetic effects involving the restriction of intramolecular motions and the prevented excimer formation for CV moieties, as endowed by host-guest interactions and the entanglement of the polymer chains. Furthermore, the SPNs can be established as efficient artificial light-harvesting systems via the inclusion of Nile red into the particles for broadened emission spectra. As a proof-of-concept study, the use of pillar[5]arene-containing polymer hosts largely facilitates the emission enhancement and wavelength adjustment for the inherent luminogens, setting the basis for the supramolecular design of highly tunable luminescent systems.

Discovery of Functional Luminescence Properties Based on Flexible and Bendable Boron-Fused Azomethine/Azobenzene Complexes with O,N,O-Type Tridentate Ligands.

Azomethine (C=N) and azo (N=N) scaffolds are a part of structural units in poly(p-phenylene azomethine) (PAM) and poly(p-phenylene azo) (PAZ), respectively. Poly(p-phenylene vinylene) (PPV) is known to be one of luminescent π-conjugated polymers, meanwhile PAM and PAZ, which are the aza-substituted PPV analogues, are regarded as weak or no emissive materials. However, by the boron complexation, intense emission can be induced. Furthermore, environment-sensitivity and stimuli-responsivity were also observed. In this review, we demonstrate unique and versatile luminescent properties based on "flexible and bendable" π-conjugated systems composed of the boron-fused azomethine and azobenzene complexes (BAm and BAz) with the O,N,O-type tridentate ligands. The "flexible and bendable" luminophores showed intriguing optical behaviors, such as thermosalient effect, aggregation-induced emission (AIE) and crystallized-induced emission (CIE). Moreover, highly efficient emissions both in solution and film states were observed from the polymers. We illustrate the results and mechanisms on these luminescent properties from the series of our recent studies with BAm and BAz complexes and polymers.

A hydrogen bond cross-linked luminescent supramolecular network polymer and its application for the detection of alkyl iodides with differentiation capabilities from aromatic iodides

A luminescent supramolecular polymer consisting of poly(4-vinyl pyridine) and perylene diimide was prepared through a H-bond cross-linking strategy and used for alkyl iodide sensing.

Tuning energy landscapes and metal-metal interactions in supramolecular polymers regulated by coordination geometry.

Herein, we exploit coordination geometry as a new tool to regulate the non-covalent interactions, photophysical properties and energy landscape of supramolecular polymers. To this end, we have designed two self-assembled Pt(ii) complexes 1 and 2 that feature an identical aromatic surface, but differ in the coordination and molecular geometry (linear vs. V-shaped) as a result of judicious ligand choice (monodentate pyridine vs. bidentate bipyridine). Even though both complexes form cooperative supramolecular polymers in methylcyclohexane, their supramolecular and photophysical behaviour differ significantly: while the high preorganization of the bipyridine-based complex 1 enables an H-type 1D stacking with short Pt⋯Pt contacts via a two-step consecutive process, the existence of increased steric effects for the pyridyl-based derivative 2 hinders the formation of metal–metal contacts and induces a single aggregation process into large bundles of fibers. Ultimately, this fine control of Pt⋯Pt distances leads to tuneable luminescence—red for 1vs. blue for 2, which highlights the relevance of coordination geometry for the development of functional supramolecular materials.

Strong circularly polarized luminescence of mixed lanthanide coordination polymers with control of 4f electronic structures.

This paper reports chiral mixed Eu(iii)-Ln(iii) coordination polymers (Ln = Gd and Sm) with a high dissymmetry factor of circularly polarized luminescence (gCPL = 0.15) for the enhancement of the emission quantum yield (Φtot ≥ 50%), achieved via control of 4f electronic structures.

Bright sky-blue fluorescence with high color purity: assembly of luminescent diphenyl-anthracene lutetium-based coordination polymer.

Pure sky-blue fluorescence (FWHM: 50 nm) from lutetium-based coordination polymer with diphenyl-anthracene derivative is demonstrated for the first time. The observed high color purity is based on the tightly packed crystal structure of the coordination polymer with multiple CH–F interactions.

Highly efficient fluorescent chemosensor for nitro antibiotic detection based on luminescent coordination polymers with 2,6-di(4-carboxyphenyl)pyrazine

A series of isostructural porous supramolecular frameworks, {[M(DCPP)(H2O)]·(DMF)}n, are synthesized. The as-obtained fluorescent Zn-MOF has good recognition ability towards nitro-antibiotics with low detection limits and a wide linear range.

Colloidal suspensions of highly luminescent lanthanide-based coordination polymer molecular alloys for ink-jet printing and tagging of technical liquids

A series of lanthanide-based coordination polymer molecular alloy colloidal dispersions usable for ink-jet printing and tagging of technical liquids.

Photo-oligomerization by shifting the coordination site in a luminescent coordination polymer.

A layered coordination polymer (CP) with the fine-tuned alignment of four diolefinic ligands has been designed by shifting the coordination site of the ligand. The trimeric and tetrameric cyclobutane derivatives were reversely achieved by the photoinitiated [2+2] cycloaddition of the CP due to the favorable Schmidt's distance. More interestingly, a dynamic fluorescence shift was observed during the photo-oligomerization and heat-cycloreversion of the CP system.

Recent developments in stimuli-responsive luminescent polymers composed of boron compounds

This review summarizes recent developments in stimuli-responsive luminescent polymers with boron chromophores, including three- and four-coordinated compounds. Sensing mechanisms based on the features of boron and polymer structures are described.

Design of ultra-high luminescent polymers for organic photovoltaic cells with low energy loss.

Here, new polymers named PBTT-Cn (n = 3, 4, or 5) have been designed based on carboxylate-functionalized thieno[3,2-b]thiophene units. The electroluminescence external quantum efficiencies (EQEEL) of pristine PBTT-C4 and C5 films are over 1 × 10-2, which are among the highest results for OPV materials. Through combination with BTP-eC9, the PBTT-C4-based film showed a high EQEEL of 6 × 10-4 and the Vnon-radloss is 0.19 eV. As a result, a high open-circuit voltage of 0.89 V and a satisfactory PCE of 15% were recorded in the PBTT-C4-based OPV cells.

Through‐space charge transfer polymers for solution‐processed organic light‐emitting diodes

AbstractThrough‐space charge transfer (TSCT) polymers are an attractive class of luminescent polymers with spatial donor/acceptor architecture and thermally activated delayed fluorescence effect, different from conventional luminescent polymers with conjugated donor‐acceptor structure and through‐bond charge transfer emission. Their emission comes from the intramolecular charge transfer by through‐space pathway because the donor and acceptor segments are spatially proximate to each other in each repeating unit but are physically separated by nonconjugated polymer backbone. In this review, recent advances in TSCT polymers with linear, bottlebrush, and dendritic architectures are presented, with the focus on their molecular design, photophysical behavior, and device performance. We hope that this review shall provide a useful insight of new luminescent polymers with TSCT effect for use in solution‐processed organic light‐emitting diodes.

Luminescence property of phosphoramidic acid oligomer nanodots in aqueous solution

Luminescent polymer dots have showed great potential applications in chemical sensing and bioimaging. Herein, phosphoramidic acid oligomers in aqueous solution can form nanodots (ONDs) with mean diameter of 50 ~ 60 nm. The ONDs display blue fluorescence of excitation-dependence and the fluorescence quantum yields can reach 4.16% to 9.71% under the maximum excitation and emission wavelengths. The steady and dynamic fluorescence quenching experiments by iodide ion show that the luminescence of ONDs originates to charge transfer (CT). The calculation on distribution of HOMO and LUMO of ONDs in monomer and dimer states supports further the CT mechanism, and the separated and localized distribution of HOMO and LUMO provides possible explanation on the excitation wavelength dependent luminescence based on internal and external CT. It is expected that the luminescent ONDS are useful in chemical or biological sensing fields.

Reversible stimuli-responsive luminescent polymers with adaptable mechanical properties based on europium-malonate complex

Luminescent polymers that are dynamic in reversible response to external stimuli are of profound interest for the development of advanced optical devices and sensors. Here, we fabricate a new class of transparent poly(urea-urethane) containing malonate moieties through simple one-pot polycondensation. When blended with different amounts of europium ions, the resultant polymer complexes show a tunable broad spectrum of mechanical properties with their modulus adjusted from 5 MPa to 60 MPa. In the meantime, the incorporation of europium endows the metallo-supramolecular polymers with fluorescence that can reversibly respond to organic solvents like acetylacetone/triethylamine as well as temperature due to the formation of dynamic europium-malonate coordination. Given that each optical or sensor field has its own requirement for materials’ mechanical properties, we believe therefore our designed stimuli-responsive luminescent polymers with adaptable mechanical properties show great potential in the applications.

Ultrastable luminescent hybrid microporous polymers based on polyhedral oligomeric silsesquioxane for CO2 uptake and metal ion sensing

In this study we prepared four different fluorescent hybrid microporous polymers (HPPs) derived from cubic octavinylsilsesquioxane (OVS) through Heck coupling with brominated anthracene (An-Br2), triphenyltriazine (TPT-Br3), bicarbazole (Car-Br4) and tetraphenylethene (TPE-Br4). The chemical structures of these HPPs were confirmed using Fourier transform infrared spectroscopy and solid-state NMR spectroscopy. Thermogravimetric analysis and N2 adsorption/desorption measurements revealed that each of these HPPs had outstanding thermal stability, a high surface area, and inherent porosity. The CO2 uptakes of TPT-HPP and Car-HPP at 273 and 298 K were higher than those of An-HPP and TPE-HPP. Furthermore, the luminescence of these HPPs could be quenched completely upon the addition of Fe2+, and Fe3+ metal cations. Thus, these HPP materials appear to be good candidates for CO2 adsorption and metal ion sensing.