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Identification performance of two luminescent lanthanide–organic frameworks
摘要： By the reaction of organic ligands, 2-(3,4-dimethylphenyl)-1H-imidazole-4,5-dicarboxylic acid (H3DMPhIDC) and terephthalic acid (H2DCB) with Eu3+ or Tb3+ ions, respectively, two luminescent metal-organic frameworks (MOFs) [Ln(H2DMPhIDC)(DCB)]n [Ln = Eu (1); Tb (2)] have been constructed. Both MOFs 1 and 2 are isostructural and show two-dimensional structures, which were fully characterized by single crystal X-ray diffraction, elemental analysis, and infrared spectroscopy. Both MOFs have excellent thermal and water stability, and indicate characteristic lanthanide metallic luminescence. Importantly, they can significantly recognize Fe3+ cation in aqoues solutions. Their sensing mechanisms have been suggested according to structural analyses, PXRD data and UV-Vis determinations.
关键词： recognition,crystal structure,luminescent MOFs,fluorescence quenching
更新于2025-09-23 15:23:52
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Structure, growth and characterization of a new naphthalene family crystal for fluorescence and third order nonlinear optical applications
摘要： In the present work we have investigated the fluorescence and nonlinear optical property of a new naphthalene family crystal, Decyl 6-(decyloxy)naphthalene-2-carboxylate (D6DN2C). This crystal was grown for the first time by slow evaporation solution technique (SEST). Single crystal X-ray diffraction analysis reveals that D6DN2C belongs to triclinic crystal system with centrosymmetric space group of Pī. The determined lattice parameters are a = 8.669(3) ?, b = 9.495(3) ?, c = 19.757(6) ?, α =82.697(1)°, β =77.726(1)°, γ = 65.465(1)°and volume = 1444.17(8)?3. Functional groups present in D6DN2C were identified by FT-IR studies. Transparency of the title crystal in UV–Visible region was analyzed and the optical band gap energy was found to be 3.51eV. Fluorescence spectra were recorded for the excitation wavelength of 300 nm. The negative third order nonlinear optical parameters like refractive index (n2), absorption coefficient (β) and susceptibility (χ(3)) were estimated by Z-scan studies.
关键词： Crystal structure,Characterization,Growth from solutions,Nonlinear optic materials,Organic compounds
更新于2025-09-23 15:23:52
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Growth, morphology and crystal structure of electrodeposited Bi2Se3 films: Influence of the substrate
摘要： In this study, we investigated the growth, morphology and crystal structure of electrodeposited Bi2Se3 films on n-Si, Au and Ru substrates. The range of potentials at which films with good quality and stoichiometry can be grown have been identified. Scanning electron micrographs of the early stages of nucleation and growth suggests the film formation on all three substrates follow the Volmer-Weber growth mode. In the case of Si substrate, a pure orthorhombic phase of Bi2Se3 could be grown which is influenced by the epitaxy of the Si substrate. The Faradaic efficiency of film growth on Si substrate was found to be around 90%. However, on Au and Ru substrates, growth of mainly the rhombohedral phase could be achieved having relatively lower Faradaic efficiencies of 68% and 78%, respectively. The Bi2Se3 films grown on Au at more negative potentials were found to exhibit improvements in the rhombohedral crystal phase. Low temperature annealing was found to transform the orthorhombic or mixed phase crystal structure to that of pure rhombohedral. The onset of phase transformation in the mixed phase Bi2Se3 films (on Au) was found to be around 125°C, determined using in-situ Raman spectroscopy. Aside from the temperature, the duration of heat treatment is identified to play a crucial role in this phase transformation. Based on our findings on room temperature deposition, we conclude that the growth of pure orthorhombic phase is favored on Si, while on Au and Ru, growth of the rhombohedral or mixed phase of Bi2Se3 could be achieved.
关键词： Raman,Annealing,Electrodeposition,Crystal structure,Substrate epitaxy,Bi2Se3,Growth
更新于2025-09-23 15:23:52
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Correlation between magneto-optical and transport properties of Sr doped manganite films
摘要： The features of electronic structure of La0.7Sr0.3MnO3, Pr0.8Sr0.2MnO3, and Pr0.6Sr0.4MnO3 polycrystalline films of different thickness have been investigated using magnetic circular dichroism (MCD) in the range of 1.1e4.2 eV. The temperature behavior of the samples electrical resistance were also has been studied. It was found that films with high Sr content (0.3 and 0.4) act as high-temperature semiconductors, while the maximum in the temperature dependences of resistivity these films indicates the transition of the samples to the metallic state at some temperature TM-S, which is different for different sample thickness. The films with the lower Sr content (0.2) act as insulators in the used temperature range. The MCD spectra have been decomposed to the Gaussian-shaped lines, and the temperature dependence of intensity of each line has been analyzed in comparison with temperature dependence of the films magnetization and with their electric conductivity type. Different temperature behavior of the intensity of four specified Gaussian-lines was revealed for semiconductor films. In the case of insulating Pr0.8Sr0.2MnO3 samples, the intensity of three specified Gaussian lines changes with the temperature in the same way as the magnetization changed. It was established that the lanthanide (La, Pr) type does not affect the MCD spectra shape for the films with the same electrical conductivity type. Besides, the correlation between the MCD data of the films and their conductivity type was revealed. Due to the detailed analysis of the specified Gaussian lines with taking into account the well-known in the literature absorption bands, lying outside the studied spectral region, the MCD bands for the studied manganite films have been identified with electronic transitions of a different nature.
关键词： Magnetic circular dichroism,Thin films,Electronic properties,Electrical transport,Crystal structure,Manganites
更新于2025-09-23 15:23:52
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A series of germanotungstate-based 3d-4f heterometallic compounds with visible-light induced photocatalytic, electrochemical and magnetic properties
摘要： A series of 3d-4f heterometallic germanotungstate dimers {[Cu(dap)(H2O)3][LnCu3(dap)3(OH)3(H2O)2(GeW11O39)]}·nH2O (Ln = SmⅢ, n = 11 (1), EuⅢ, n = 12 (2), GdⅢ, n = 10 (3) and TbⅢ, n = 13 (4); dap = 1, 2-diaminopropane) have been prepared under hydrothermal conditions and structurally characterized by IR, UV-Vis, XRD, and X-ray single-crystal diffraction. Compounds 1–4 are essentially isomorphic and display organic-inorganic hybrid dimeric structures consisting of [LnCu3(dap)3(OH)3(H2O)(GeW11O39)]2 4– with two supporting [Cu(dap)(H2O)3]2+ cations on both sides. The four compounds all exhibit the excellent photocatalytic activities to delaradation of methylene blue (MB) and rhodamine-B (RhB) under visible light irradiation in the presence of H2O2. Additionally, 1–4 displays an apparent electrocatalytic activity for the reduction of hydrogen peroxide. The variable-temperature magnetic studies show that the magnetic behaviours of 1, 2 and 4 are dominated by antiferromagnetic coupling interactions, while that of 3 is ferromagnetic interactions coexist along with antiferromagnetic interactions.
关键词： Photocatalytic properties,Lacunary polyoxometalates,magnetic properties,Crystal structure,Electrocatalytic properties,3d-4f Heterometallic compounds
更新于2025-09-23 15:23:52
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Synthesis and photoluminescence properties of different structural cuprous complexes regulated by benzoxazole ligands and halogen/pseudohalide ions
摘要： Reaction of 2-(2’-pyridyl)benzoxazole (2-PBO), 2-(4’-pyridyl)benzoxazole (4-PBO) and 2,2-(1,4-butanediyl)bis-1,3-benzoxazole (BBO) ligands with CuX (X = I, Br, SCN) afforded a binuclear copper(I) complex [Cu(2-PBO)(μ2-I)]2 (1) and three copper(I) coordination polymers [Cu4(4-PBO)4(μ3-I)4]n (2), {[Cu(4-PBO)(μ3-SCN)]2}n (3) and {[Cu(BBO)(μ2-Br)]2}n (4). The structural analysis revealed that the all copper(I) ions are four-coordinated and the geometric structure around the central copper(I) atom possessing slightly distorted tetrahedral geometry in complexes 1-4. Halogen or pseudohalide ions can not only act as counter anions, but also as ligands participation in coordination when the cuprous ion coordination sites are not saturated. Due to the different coordination modes of the benzoxazole ligands, in order to satisfy the tetra-coordination of cuprous ions, halogen or pseudohalide ions adopt μ2 and/or μ3-bridging modes to synergistically complete coordination. Photoluminescence investigation show that complexes 1, 3 and 4 have two emission peaks, the high energy band peak is attributed to MLCT[d10(Cu)→π*] and XMCT, the low energy band peak is caused by the 3CC emission. This may be due to the presence of μ2-X (X=I, Br, S) in these complexes. However complex 2 only had one emission peak, which may be attributed to MLCT[d10(Cu)→π*] and XMCT.
关键词： Cuprous complex,Charge-transfer,Photoluminescence,Crystal structure,Benzoxazole
更新于2025-09-23 15:23:52
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A triple alkoxo bridged dinuclear cobalt(III) complex mimicking phosphatase and showing ability to degrade organic dye contaminants by photocatalysis
摘要： A dinuclear cobalt(III) complex, [(N3)L1CoIIIL2CoIIIL1] (1), has been synthesized and characterized {H2L1 = 2-((1-hydroxybutan-2-ylimino)methyl)-4-bromophenol and HL2 = 2-amino-1-butanol}. Single crystal X-ray diffraction analysis confirmed its structure. Extended supra-molecular architectures were generated in the complex through weak noncovalent interactions. The energetic features of significant supramolecular interactions have been investigated using DFT calculation and further corroborated with NCI plot index computational tool. The complex has been found to mimic the role of phosphatase enzyme efficiently by transforming 4-nitrophenylphosphate to 4-nitrophenolate at room temperature. The reaction follows Michaelis–Menten enzymatic reaction kinetics with turnover numbers of ~1.4 s-1 in aqueous DMF (98% DMF, v/v) medium. The complex also acts as an efficient photocatalyst for degradation of organic pollutants. Methylene blue (MB), a widely used dye in various industries, was selected as a model pollutant in aqueous media to evaluate the photocatalytic effectiveness of the complex.
关键词： DFT calculation,phosphatase mimicking activity,Photocatalytic degradation of methylene blue (MB),Cobalt(III),Crystal structure
更新于2025-09-23 15:23:52
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A microporous Tb-MOF luminescent sensor based on a flexible tricarboxylate for highly sensitive detection of acetone and Fe3+ ions in aqueous and isopropanol
摘要： One novel microporous terbium (III) framework, [Tb(DBB)(H2O)2](1), has been prepared from 4-(3,5-dicarboxylatobenzyloxy) benzoic acid (DBB) with terbium salt under hydrothermal condition. Structural analysis shows complex 1 possesses three-dimensional frameworks based on 2D double sheets linking by DBB ligands into porous channels. The gas adsorption experiments of N2 and CO2 show that complex 1 possesses microporous properties. Fluorescence analyses exhibit the characteristic luminescence of Tb3+ ion both in solid state and in aqueous. In particular, the Tb-MOF can detect acetone for its luminescence entirely quenching in acetone. Furthermore, the ionic detection experiments indicate complex 1 could be a good sensor for highly and sensitively sensing Fe3+ ion in aqueous and isopropanol, and the detection limit could reach at 10?9 M in aqueous.
关键词： The microporous Tb-framework,Luminescent sensor for acetone and Fe(III) ion,Crystal structure
更新于2025-09-23 15:23:52
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Identification and structures of the X-ray induced luminescence centers in the zeolites Zr,X,Cs,Na-LTA, X = Cl, Br, and I
摘要： Zr4+ and halide anions were introduced into zeolite A (LTA) by treating Cs,Na-A with ZrX4(g), X = Br and I, under anhydrous conditions. The crystal structures of Zr,Br,Cs,Na-A and Zr,I,Cs,Na-A were determined by single-crystal crystallography with compositional confirmation by scanning electron microscopy energy-dispersive X-ray (SEM-EDX) analysis. Their X-ray induced luminescence (XIL) properties were thoroughly studied. These structures and XIL properties were compared with those of previously reported Zr,Cl,Cs,Na-A. In both structures, most Na+ and Cs+ ions occupy positions similar to those found in Cs,Na-A and Zr,Cl,Cs,Na-A. About 9% of the large cavities of Zr,Br,Cs,Na-A are centered by ZrBr6 2- ions. In Zr,I,Cs,Na-A, about 6% are centered by ZrI6 2-. These octahedral ZrX6 2- ions are each held in place and stabilized in their large cavities by 24 bonds between all six of its halide ions and eight surrounding Cs+ ions. They are further bridged by 8-ring Cs+ ions to form a cubic 3-dimensional Cs11ZrX6 9+ continuum in the surface volume of the crystal. Their XIL domain peaks have red-shifted from 495 nm for Zr,Cl,Cs,Na-A, to 520 nm for Zr,Br,Cs,Na-A, and to 640 nm for Zr,I,Cs,Na-A. This may be because the self-trapped excitons (STE) of ZrBr6 2- and ZrI6 2- have smaller band gaps than that of ZrCl6 2-, a result of the valence band maximum 4p energy level in Br- being higher (5p in I- even higher) than the 3p energy level in Cl-.
关键词： ZrBr6 2- and ZrI6 2-,Crystal structure,Extraframework Zr4+,Luminescence,Zeolite A
更新于2025-09-23 15:23:52
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Synthesis, crystal structures, second harmonic generation response and temperature phase transitions of two noncentrosymmetric Cu(II)-hybrid halides compounds: [(R)-C7H16N2][CuX4] (X?= Cl or Br)
摘要： (R)-(+)-3-aminoquinuclidine was used in the synthesis of [(R)-C7H16N2][CuCl4] (1) and [(R)-C7H16N2][CuBr4] (2), which both contain similar [CuX4]2- anions (X = Cl or Br). The structures of the two compounds were determined using single-crystal X-ray diffraction. The use of enantiomerically pure sources of (R)-C7H14N2 forces crystallographic noncentrosymmetry. These materials crystallize in the chiral space group P212121 (No. 19), which exhibits the enantiomorphic crystal class 222 (D2). In the molecular arrangement, the [CuX4]2- anions are linked to the organic cations through N-H...X and C-H...X hydrogen bonds to form cation-anion-cation molecular units, which are held together by means of offset face-to-face interactions giving a three-dimensional network. Thermal stability of the crystals was ascertained by TG measurement. Compounds (1) and (2) display several phases transition with higher transition temperature at T = 100°C. The Kurtz and Perry powder method using Nd:YAG laser shows that their second harmonic generation (SHG) efficiencies are about 0.81 and 0.82 times as large as that of KH2PO4 (KDP), respectively. Such a chiral hybrid metal halides skeleton could provide a new platform for future engineering in the areas including information storage, light modulators and optoelectronic functionalities.
关键词： nonlinear optics,second harmonic generation,crystal structure,chiral hybrid halide,phase transitions
更新于2025-09-23 15:23:52