Two novel zirconium-based heterometal–organic framework catalysts can effectively improve photocatalytic activities for CO 2 photoreduction under visible light.
Using 2,5-dimethyl-1,3,4-thiodiazole (L) as ligand, a series of Ag(I), Cu(II) and Ni(II) complexes, namely, [Ag4(μ2-L)6(H2O)2](ClO4)4·2H2O (1), [Ag4(μ2-L)4(μ2-CF3CO2)2(μ3-CF3CO2)2] (2), [Ag2(μ2-L)3(CH3CN)2](AsF6)2 (3), [Ag2(μ2-L)2(μ2-NO3)2]n (4), [Cu(L)2(μ2-NO3)2] (5), [Cu(μ2-L)(μ1,1-N3)3(μ2-CH3COO)]n (6) and [Ni9(μ2-L)6(L)3(μ6-CO3)2(DMF)3(H2O)6(μ3-OH)6]2[Ni9(μ2-L)6(μ6-CO3)2(H2O)12(μ3-OH)6](ClO4)24·9H2O (7) were isolated and their crystal structures determined via single-crystal X-ray diffraction. In 1, six L ligands bridge four neighboring Ag(I) centers forming a tetranuclear cation Ag4 cluster. While in 2, μ3-CF3CO2− anions bridge two pairs of di-nuclear silver(I) clusters forming another type of tetranuclear neutral Ag4 cluster. 3 is a dinuclear Ag(I) complex and 4 is a one-dimensional (1D) chain constructed via dinuclear Ag(I) sub-units, in which μ2-NO3− groups bridge neighboring di-nuclear Ag(I) clusters into a 1D polymeric chain. When Cu(NO3)2 was employed in the reaction system instead of silver(I) salts, a mono-nuclear Cu(II) complex 5 was obtained. When Cu(Ac)2 and NaN3 were further introduced in to the reaction system of 5 instead of Cu(NO3)2, a 1D copper(II) chain 6 constructed with dinuclear copper(II) units was isolated, in which three different types of bridging (μ1,1-azido, acetate and L ligands) can be simultaneously observed. It is interesting that when self-assembly of Ni(ClO4)2·6H2O, L, Na2CO3, and NaN3 in the molar ratio of 4 : 2 : 1 : 8 in CH3OH/DMF/H2O produced well-shaped green crystals of 7. Structural analysis revealed that 7 contains two types of Ni9 clusters with an overall Pc1 non-central symmetry. To our knowledge, 7 represents a unique example of M9L6 and M9L9 cages. The result also reveals that it can be expected that using L ligands as precursors has great potential for constructing these functional materials with intriguing structural motifs such as polynuclear metal clusters. Electrospray ionization mass spectrometry measurements studies for 1–4 demonstrate that in a DMSO solution, complex 1 can still retain the form of a tetranuclear silver(I) cluster. In the solid state, complexes 1–4 exhibit strong fluorescent emission bands, which may be assigned to ligand-to-metal charge transfer. The luminescent properties of these complexes in a DMSO solution varied from blue light to green light at ambient temperature.
In this paper, the PZT nano-ceramics were prepared by an improved Sol-Gel method. This method was based on recording to A.S.Mischenko. TF Analyzer 2000 FE was used to measure the ferroelectric properties of the samples. The results show the change trends of the P-E hysteresis loops in different voltages, temperatures and frequencies. Impedance was tested by precision impedance analyzers 6500 series. With the use of the equivalent circuit to simulate the piezoelectric ceramic vibrator we can get a conclusion that in the 85 MHz-120 MHz the response of the sample can be represented with a RLC series resonant circuit. The resonant frequency of the sample is 97.12MHz, and the loss is very low. Compared with the general piezoelectric vibrator PZT 95/05 nano-ceramic is a low frequency capacitor with the capacitance tend to 0 F.
Diphenyl Sulfoxide(DPhSO)Complexes with EuropiumTerbium mixed system are prepared and characterized by IR spectra,fluorescence and Xray diffraction. In the fluorescence experiments it was found that in the mixed complexes Europium (Ⅲ) makes Terbium (Ⅲ) complex fluoresce weaker,Terbium (Ⅲ) makes Europium (Ⅲ) complex fluoresce stronger.
Using the benzene-based bis-triazole ligand 1,4-di-(1,2,4-triazole-4-yl)benzene(L) and corresponding zinc(II) salt, under hydrothermal conditions, a novel luminescent 1D Zn(II) coordination polymer, {[Zn(μ2-L)(H2O)4]SiF6·2H2O}n (1) has been isolated and characterized by single-crystal X-ray diffraction, FT-IR, and luminescent analysis. The crystal crystallizes in the Monoclinic C2/c space group, a = 12.997(5) Å, b = 19.376(4) Å, c = 8.080(6) Å, β = 109.379(18)°, Z = 4. These L ligands adopt the bi-dentate bridging coordination modes to link neighboring Zn(II) ions forming 1D chain structure. Solid state luminescent spectrum of 1 also has been investigated indicating the strong emission band centered at 370 nm. The result also represents a good example of the construction of these highly dimensional luminescent inorganic-organic hybrid frameworks.
As the world’s population structure is aging and China is at a critical stage in consolidating the results of poverty alleviation, this study intends to explore the pathways of the elderly group, which is very vulnerable to falling back into poverty, to prevent or slow down the possibility of this group falling back into poverty. In this study, 79 elderly farmers’ data were collected by household interviews as research samples, and the Vulnerability as Expected Poverty index was selected to measure the dynamic changes of poverty in aging farmers in Donglu Island Village. The correlation between the participation of aging farmers in the tourism industry and their own poverty vulnerability was analyzed through multiple linear regression. It is found that whether aging farmers participate in tourism is not correlated with their absolute poverty vulnerability. Whether aging farmers participate in tourism is significantly negatively correlated with their relative poverty vulnerability, and developing rural tourism and increasing the participation of aging farmers can alleviate the poverty vulnerability of aging farmers. Finally, with the mindset of “teach a man to fish and you feed him for a lifetime”, the development of rural tourism suitable for aging farmers is proposed.
In this work the multi-dentate 4-amino-benzene-1,2,4-triazole (L1) ligand is used. A series of novel cluster-based micro-porous luminescent cadmium(II) frameworks, namely [Cd3(μ3-L1)2(μ2-L1)2(μ2-Cl)2Cl4]n (1), {[Cd2(μ3-L1)2(μ2-Br)2Br2]·1.05H2O}n (2) and {[Cd2(μ2-L1)3(L1)2(μ2-I)2]·(CdI4)·1.5H2O}n (3) have been isolated under hydrothermal conditions. 1 presents a 4-connected (4,4) topology using trinuclear Cd(II) clusters as basic nodes. For 1, two bridging μ2-Cl− anions and two bridging μ3-L1 ligands connect three neighboring CdII ions forming trinuclear Cd3 clusters. Each Cd3 cluster links four neighboring Cd3 clusters forming a 2D (two-dimensional) neutral micro-porous framework. 1D rhombic channels with dimensions of 7.594(2) Å × 21.250(6) Å can be observed along the c-axis. 2 presents a rare I1O3 hybrid type micro-porous framework. In 2 these bridging μ3-L1 ligands link central CdII ions forming a 3D Cd–L1 organic connectivity. Two kinds of 1D Cd–Br–Cd inorganic connectivities further consolidate the 3D Cd–L1 organic connectivity, which ultimately forms a rare I1O3 type hybrid framework. 3 presents a novel 3D cluster-based micro-porous cation framework containing 1D channels, in which guest CdI42− anions and water molecules are located. Topological analysis indicates that 3 presents a novel 4-connected dmp topology using binuclear Cd2I2 clusters as basic nodes. PXRD, TGA and Gas absorption experiments for 1–3 have also been carried out. Solid state photo-luminescent spectra of 1–3 have been determined indicating strong emission bands. For 1 selective photo-luminescent quenching for NO2− anions can be observed. The result also reveals that L1 can adopt various different coordinated modes and flexible spatial distortion dihedral angles (between aromatic benzene and triazole rings), which has great potential in the construction of these novel cluster-based micro-porous coordination frameworks.
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