Robust Lanthanoid Picolinate-Based Coordination Polymers for Luminescence and Sensing Applications.
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ABSTRACT:
SUBMITTER: Jornet-Molla V
PROVIDER: S-EPMC8454995 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:In this work are presented all the conditions of synthesis explored to obtain a new family of compound with formula [Ln(4-OHBBA)3(H2O)2] (Ln = La, Pr). Powder X ray diffraction was used to identify the different phases obtained in the synthetic study. FT-IR spectroscopy and TG analysis for La and Pr pure phases are also reported. Optical properties of optically active CPs materials, solid state photoluminescence properties of La, Pr, La-(5%Eu) and La-(5%Tb) compounds were explored. We report the absorption, excitation and emission spectrum of the 4'-hydroxi-4-biphenylcarboxylic acid and a comparative description of the radiative (and no-radiative) processes in solid state in Ln-(4-OHBBA) and Ln-BPDC compounds. Finally, a principal component analysis was conducted in order to take in account both signal contributions from the sensor (LCE at 384 nm and the europium emission at 610 nm) and for classifying the type of analytes used to test the sensing response of the materials.
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Project description:By utilizing a novel octacarboxylate-functionalized resorcin[4]arene as organic linkers, three lanthanide-coordination polymers, namely, [(CH3)2NH2][Ln2(HL)(H2O)7]·2H2O (Ln = Tb (1), Eu (2) and Gd (3), H8L = 2,8,14,20-tetra-pentyl-4,6,10,12,16,18,22,24-octa-carboxymethoxy-resorcin[4]arene) have been solvothermally synthesized and structurally characterized. Isostructural 1-3 display unique two dimensional sandwich-based layers built with Ln3+ cations and bowl-shaped HL7- anions. Remarkably, 1 and 2 produce intensive green and red emissions respectively and long lifetimes thanks to the antenna effect of HL7- anions. The energy level testing of 3 indicates that the newly designed ligand H8L has a very efficient intersystem crossing process. More importantly, luminescent investigations reveal that 1 and 2 can selectively detect N,N'-dimethylformamide and Fe3+ ions with turn-on-type and turn-off-type responses, respectively.
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Project description:The rare earth complexes and the polymers can be made into composite nanofibers through electrospinning. The fluorescence intensity of these fiber composites is much higher than that of the rare earth complexes. By changing the mixed proportion of polymethyl methacrylate (PMMA) and complexes, nanofiber materials were prepared. Then, by measuring their fluorescence intensity, it is found that the carbonyl bond of PMMA may have coordinated with the rare earth ions and enhanced the luminescence intensity of them. Then, a series of experiments were designed to study their coordination and luminescence mechanism. The coordination mechanism of the polymers with carbonyl groups and the rare earth complexes was explained by Eu(TFT)?(TPPO), Eu(TFT)?(TPPO)?, Eu(PFP)?(TPPO), Eu(PFP)?(TPPO)?, and polyvinyl pyrrolidone (PVP) dissolved in chloroform solution, where TFT means 2-(2,2,2-trifluoroethyl)-1-tetralone, PFP means 2-(2,2,3,3,3-Pentafluoropro-panoyl)-3,4-dihydronaphthalen-1(2H)-one and TPPO means phosphine oxide. The coordination of PVP and the rare earth complexes in solution was studied, and it was found that the fluorine atoms of the ligand had a significant impact on the aggregation-induced effect of the composites. The electron transitioned in the polymers and the complexes were enhanced greatly by the coordination. The colors of emission light could be adjusted by the coordination of the polymers and the rare earth complexes.
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Project description:Polymer-based composites reinforced with nanocarbonaceous materials can be tailored for functional applications. Poly(vinylidene fluoride) (PVDF) reinforced with carbon nanotubes (CNT) or graphene with different filler contents have been developed as potential piezoresistive materials. The mechanical properties of the nanocomposites depend on the PVDF matrix, filler type, and filler content. PVDF 6010 is a relatively more ductile material, whereas PVDF-HFP (hexafluropropylene) shows larger maximum strain near 300% strain for composites with CNT, 10 times higher than the pristine polymer. This behavior is similar for all composites reinforced with CNT. On the other hand, reduced graphene oxide (rGO)/PVDF composites decrease the maximum strain compared to neat PVDF. It is shown that the use of different PVDF copolymers does not influence the electrical properties of the composites. On the other hand, CNT as filler leads to composites with percolation threshold around 0.5 wt.%, whereas rGO nanocomposites show percolation threshold at ≈ 2 wt.%. Both nanocomposites present excellent linearity between applied pressure and resistance variation, with pressure sensibility (PS) decreasing with applied pressure, from PS ≈ 1.1 to 0.2 MPa-1. A proof of concept demonstration is presented, showing the suitability of the materials for industrial pressure sensing applications.
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Project description:In the present research, the concept of developing a novel system based on polymer-enzyme macromolecules was tested by coupling carboxylic acid functionalized poly(vinyl alcohol) (PVA-COOH) to glucose oxidase (GOx) followed by the bioconjugation with CdS quantum-dots (QD). The resulting organic-inorganic nanohybrids were characterized by UV-visible spectroscopy, infrared spectroscopy, Photoluminescence spectroscopy (PL) and transmission electron microscopy (TEM). The spectroscopy results have clearly shown that the polymer-enzyme macromolecules (PVA-COOH/GOx) were synthesized by the proposed zero-length linker route. Moreover, they have performed as successful capping agents for the nucleation and constrained growth of CdS quantum-dots via aqueous colloidal chemistry. The TEM images associated with the optical absorption results have indicated the formation of CdS nanocrystals with estimated diameters of about 3.0 nm. The "blue-shift" in the visible absorption spectra and the PL values have provided strong evidence that the fluorescent CdS nanoparticles were produced in the quantum-size confinement regime. Finally, the hybrid system was biochemically assayed by injecting the glucose substrate and detecting the formation of peroxide with the enzyme horseradish peroxidase (HRP). Thus, the polymer-enzyme-QD hybrid has behaved as a nanostructured sensor for glucose detecting.
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Project description:Solvothermal reactions of lanthanide (III) salts with 1,2-phenylenediacetic acid in N,N'-dimethylformamide (DMF) solvent lead to the formation of the metal complexes of the general formula Ln2(1,2-pda)3(DMF)2, where Ln(III) = Pr(1), Sm(2), Eu(3), Tb(4), Dy(5), and Er(6), 1,2-pda = [C6H4(CH2COO)2]2-. The compounds were characterized by elemental analysis, powder and single-crystal X-ray diffraction methods, thermal analysis methods (TG-DSC and TG-FTIR), infrared and luminescence spectroscopy. They exhibit structural similarity in the two groups (Pr, Sm, and Eu; Tb, Dy, and Er), which was reflected in their thermal behaviours and spectroscopic properties. Single-crystal X-ray diffraction studies reveal that Sm(2) and Eu(3) complexes form 2D coordination polymers with four crystallographically independent metal centers. Every second lanthanide ion is additionally coordinated by two DMF molecules. The 1,2-phenylenediacetate linker shows different denticity being: penta- and hexadentate while carboxylate groups exhibit bidentate-bridging, bidentate-chelating, and three-dentate bridging-chelating modes. The infrared spectra reflect divergence between these two groups of complexes. The complexes of lighter lanthanides contain in the structure coordinated DMF molecules, while in the structures of heavier complexes, DMF molecules appear in the inner and outer coordination sphere. Both carboxylate groups are deprotonated and engaged in the coordination of metal centers but in different ways in such groups of complexes. In the groups, the thermal decomposition of the isostructural complexes occurs similarly. Pyrolysis of complexes takes place with the formation of such gaseous products as DMF, carbon oxides, ortho-xylene, ethers, water, carboxylic acids, and esters. The complexes of Eu and Tb exhibit characteristic luminescence in the VIS region, while the erbium complex emits NIR wavelength.
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Project description:We present a coordination polymer based on rare-earth metal centers and carboxylated 4,4'-diphenyl-2,2'-bipyridine ligands. We investigate Y3+, Lu3+, Eu3+, and a statistical mixture of Y3+ with Eu3+ as metal centers. When Y3+ or Lu3+ is exclusively present in the coordination polymer, biluminescence from the ligand is observed: violet emission from the singlet state (417 nm, 0.9 ns lifetime) and orange emission from the triplet state (585 nm, 76 ms (Y3+) and 31 ms (Lu3+)). When Eu3+ is present in a statistical mixture with Y3+, red emission from the Eu3+ (611 nm, ∼500μs ) is observed in addition to the ligand emissions. We demonstrate that this multi-mode emission is enabled by the immobility of singlet and triplet states on the ligand. Eu3+ only receives energy from adjacent ligands. Meanwhile, in the broad inhomogeneous distribution of ligand energies, higher energy states favor singlet emission, whereas faster intersystem crossing in the more stabilized ligands enhances their contribution to triplet emission.
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Project description:Materials with aggregation-induced emission (AIE) properties have received increased attention recently due to their potential applications in light-emitting devices, chemo/biosensors and biomedical diagnostics. In general, AIE requires the forced aggregation of the AIEgens induced by the poor solvent or close arrangement of AIEgens covalently attached to polymer chains. Here, we report two coordination-enhanced fluorescent supramolecular complexes featuring hierarchically restricted intramolecular motions via the self-assembly of tetraphenylethylene (TPE)-based tetra-dentate (La) and bidentate (Lb) ligands and the cis-Pd(en)(NO₃)₂ (en = ethylenediamine) unit. While the free ligands are non-emissive in dilute solution and show typical AIE properties in both mixed solvent system and the solid state, the self-assembled complexes maintain their fluorescent nature in the solution state. In particular, the Pd₄(La)₂ complex shows remarkable 6-fold fluorescent enhancement over La in dilute solution. We anticipate that these kinds of coordination-enhanced emissive supramolecules will find applications in biomedical sensing or labeling.
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Project description:Coordination polymers with a new rigid ligand 1,3-bis(1,2,4-triazol-1-yl)adamantane (L) were prepared by its reaction with cadmium(II) or silver(I) nitrates. Crystal structure of the coordination polymers was determined using single-crystal X-ray diffraction analysis. Silver formed two-dimensional coordination polymer [Ag(L)NO3]n, in which metal ions are linked by 1,3-bis(1,2,4-triazol-1-yl)adamantane ligands, coordinated by nitrogen atoms at positions 2 and 4 of 1,2,4-triazole rings. Layers of the coordination polymer consist of rare 18- and 30-membered {Ag2L2} and {Ag4L4} metallocycles. Cadmium(II) nitrate formed two kinds of one-dimensional coordination polymers depending on the metal-to-ligand ratio used in the synthesis. Coordination polymer [Cd(L)2(NO3)2]n was obtained in case of a 1:2 M:L ratio, while for M:L = 2:1 product {[Cd(L)(NO3)2(CH3OH)]·0.5CH3OH}n was isolated. All coordination polymers demonstrated ligand-centered emission near 450 nm upon excitation at 370 nm.
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Project description:Two-dimensional layered coordination polymers based on the hetero-substituted 3-chloro-6-cyano-2,5-dihydroxybenzoquinone ligands, hereafter ClCNAn2- anilate, and LnIII ions (Tb and Eu) are reported. Compounds 1 and 2, formulated as Ln2(ClCNAn)3(DMSO)6 (LnIII = Tb, 1; Eu, 2), and their related intermediates 1' and 2', formulated as Ln2(ClCNAn)3(H2O)x·yH2O (x + y likely = 12, Ln = Tb, 1'; and Eu, 2'), were prepared by a conventional one-pot reaction (the latter) and recrystallized from DMSO solvent (the former). Polyhydrated intermediates 1' and 2' show very similar XRPD patterns, while, despite their common stoichiometry, 1 and 2 are not isostructural. Compound 1 consists of a 2D coordination framework of 3,6 topology, where [Tb(DMSO)3]III moieties are bridged by three bis-chelating ClCNAn2- ligands, forming distorted hexagons. Ultrathin nanosheets of 1 were obtained by exfoliation via the liquid-assisted sonication method and characterized by atomic force microscopy, confirming the 2D nature of 1. The crystal structure of 2, still showing the presence of 2D sheets with a "hexagonal" mesh and a common (3,6) connectivity, is based onto flat, non-corrugated slabs. Indeed, at a larger scale, the different "rectangular tiles" show clear roofing in 1, which is totally absent in 2. The magnetic behavior of 1 very likely indicates depopulation of the highest crystal-field levels, as expected for TbIII compounds.
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