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In order to boost the electromechanical coupling factor and decrease the characteristic impedance, a 1-3 piezoelectric composite with a 3-tier polymer structure was designed and fabricated, in which epoxy resin constitutes the middle layer and silicone rubber is used to clamp the epoxy. The effective parameters of the composite, such as resonant frequency, electromechanical coupling factor, and characteristic impedance, were studied by the finite element method and experiment. The experimental results indicate that the electromechanical coupling factor of the composite is enhanced by 8.4% and the characteristic impedance is decreased by 52.8%, compared with the traditional 1-3 ceramic/epoxy composite.

As a country that is poor in petroleum yet rich in coal, it is significant for China to develop direct coal liquefaction (DCL) technology to relieve the pressure from petroleum shortages to guarantee national energy security. To improve the efficiency of the direct coal liquefaction process, scientists and researchers have made great contributions to studying and developing highly efficient hydrogen donor (H-donor) solvents. Nevertheless, the details of hydrogen donation and the transfer pathways of H-donor solvents are still unclear. The present work examined hydrogen donation and transfer pathways using a model H-donor solvent, tetralin, by density functional theory (DFT) calculation. The reaction condition and state of the solvent (gas or liquid) were considered, and the specific elementary reaction routes for hydrogen donation and transfer were calculated. In the DCL process, the dominant hydrogen donation mechanism was the concerted mechanism. The sequence of tetralin donating hydrogen atoms was &alpha, H (C1&ndash, H) &gt, &delta, H (C4&ndash, &beta, H (C2&ndash, &gamma, H (C3&ndash, H). Compared to methyl, it was relatively hard for benzyl to obtain the first hydrogen atom from tetralin, while it was relatively easy to obtain the second and third hydrogen atoms from tetralin. Comparatively, it was easier for coal radicals to capture hydrogen atoms from the H-donor solvent than to obtain hydrogen atoms from hydrogen gas.

A (3,12)-connected 3D inorganic luminescent lanthanide hydroxide cluster polymer [Eu6(μ6-O) (μ3-OH)8(H2O)6(SO4)4] n (1) has been hydrothermally synthesized and characterized. The structure can be considered to be constructed by linking 12-connected octahedral hexanuclear lanthanide oxido/hydroxide clusters with 3-connected inorganic SO4 2− anions. Presently, it is the first 3D inorganic lanthanide cluster polymer based on octahedral hexanuclear lanthanide cluster with the highest connected binodal network topology. 1 displays red luminescent emission and exhibits the characteristic transitions of the Eu3+ ion with a decay lifetime of 196.25 μs in the solid state at room temperature. .

The sidewalls of multiwalled carbon nanotubes (MWCNTs) were decorated with CdS nanoparticles using a mild two-step approach, with in situ polymerized thiophene (PTh) acting as an interlinker. Extensive characterization of the materials has been carried out using transmission electron microscopy, selected area electron diffraction, X-ray diffraction, thermal gravimetric analysis, ultraviolet–visible absorption spectroscopy and photoluminescence spectroscopy. Optical limiting (OL) studies have been performed using the open Z-scan technique at the laser wavelengths of 532 and 1064 nm. The MWCNT–PTh–CdS system shows an enhanced OL effect in comparison to the pristine MWCNTs, particularly at 1064 nm. Possible underlying mechanisms are proposed based on the results of nonlinear scattering measurements.

A novel and simple oligodeoxyribonucleotide-based sensor with single fluorophore-labeled for mercury ion sensing was reported. An oligodeoxyribonucleotide poly(dT) was labeled with fluorescein as donor. Based on the specific binding of Hg(II) to T–T mismatch base pairs, the formation of π-stacked [T–Hg(II)–T] with “sandwich” structure on the addition of Hg(II) ions facilitates the electron transfer via photoinduced charge transfer (PCT), which creates an additional nonradiative decay channel for excited fluorophore and triggers the fluorescence to be quenched. The π-stacked [T–Hg(II)–T] functioned not only as mercury ion recognition but also as an electron acceptor to quench the donor. A linear relationship was observed over the range of 0–1.0 μM with the detection limit of 20 nM for mercury ions. The fluorescence quenching phenomenon and quenching mechanism, reliability and selectivity of the system were investigated in detail.

Three rare-earth complexes with 3-methylbenzoic acid (HL) have been hydrothermally synthesized directly: Yb(C8H7O2)3 1 and Ln(C8H7O2)3·(4,4′-bipy)0.5 (Ln = Eu 2, Gd 3) (4,4′-bipy = 4,4′-bipyridine).The crystal structures were determined by single crystal X-ray diffraction with the following data: 1: monoclinic, P21/n, a = 13.574(3), b = 8.0438(2), c = 20.652(4) A, β = 96.14(3)°; 2: triclinic, P-1, a = 8.1788(2), b = 12.952 (3), c = 12.968(3) A, α = 94.400(3)°, β = 92.260(4), γ = 101.360(4); the complex 1 is a one-dimensional chain. However, due to the existence of the second ligand-4,4′-bipy, the complexes 2 and 3 are a two-dimensional layer, the Lanthanide contraction makes the difference of the structure between the complexes at the same time. Additionally, in order to explore the structural characteristic, the 2D-IR correlation spectroscopy containing the temperature-induced structural variations and magnetism-induced structural variations is used. Photo-luminescent properties of 1 and 2 are discussed in detail.

Two-dimensional correlation infrared spectroscopy (2D-COS) were employed to investigate temperature-dependent spectral variations [(PO 4 ) 2 Mo 5 O 15 ] 6− , β-[Mo 8 O 26 ] 4− , [PMo 12 O 40 ] 3− , [P 2 W 18 O 60 ] 6− cluster anions. Two-dimensional correlation spectra in 800–1000 cm −1 region provides information about the variations of the terminal Mo O bonds in the polyoxomolybdenum (or Polyoxotungstic) cluster anions. In 600–800 cm −1 region, it reveals the information about the variations of the bridging Mo O Mo bonds in the cluster anions. The results indicated that the intensity change of the terminal Mo O bonds are more sensitive than the bridging Mo–O–Mo bands to the temperature variation. Furthermore, from [(PO 4 ) 2 Mo 5 O 15 ] 6− , β-[Mo 8 O 26 ] to [PMo 12 O 40 ] 3− , with the cluster anions becoming larger, the 2D-IR spectra showed the bridging Mo–O–Mo bonds in the cluster anions were becoming more sensitive to temperature variation.

Two isomeric forms of the octamolybdate cluster, (NH{sub 4}){sub 2}(Hbpy){sub 2}[Mo{sub 8}O{sub 26}](bpy){sub 3} 1 (bpy=bipydine), and [Cu{sub 2}(imi){sub 4}]{sub 2}[Mo{sub 8}O{sub 26}] 2 (imi=imidazole), were synthesized by hydrothermal method and characterized by X-ray single analysis, one-dimensional (1D) infrared spectroscopy and two-dimensional (2D) correlation infrared spectroscopy under thermal perturbation. In compound 1, the [Mo{sub 8}O{sub 26}] units are {beta}-structure, and octamolybdate anion is {zeta}-structure in compound 2. The 2D IR correlation spectroscopy study indicates that the intensity changes of Mo=O band are more sensitive to the temperature variation than that of the Mo-O bond. The {mu}-Mo-O bond and framework vibrations in compound 1 are more sensitive to the temperature variation than that for compound 2. As the vibrations of {mu}-Mo-O bond accompanied by the transfer of an oxygen atom, the catalysis ability of compound 1 may be higher than that of compound 2. - Graphical abstract: Synchronous and asynchronous correlation spectra of compounds 1 and 2 over a temperature range from 50 to 120 deg. C in the range of 400-1000 cm{sup -1}. Display Omitted.

Two 3D coordination polymers with different structure motifs, [Zn2(PCPA)2(IN)2]n (1) and [Co(PCPA)(IN)]n (2) (PCPA=p-chlorophenoxyacetate, IN=isonicotinate), first constructed from mixed rigid and flexible carboxylate ligands, have been obtained under hydrothermal condition and characterized by elemental analyses, IR spectra, thermogravimetric analysis, fluorescent spectra and single crystal X-ray diffraction analysis. The most intriguing structural feature is that each complex exhibits both infinite helical Zn(μ2-carboxylate) or Co(μ3-carboxylates) chain units with 21 helices and zigzag M2(IN)2 (M=zinc and cobalt) chain units by reason of two different carboxylate ligands coordinating to metal centers. Additionally, compounds 1 and 2 show similar blue fluorescence in the solid state at room temperature.

A novel compound, (Himi)(H(3)O) [Cu(imi)(2)](2)[P(2)Mo(5)O(23)].H(2)O 1 (imi=imidazole), was synthesized by hydrothermal method and characterized by X-ray single analysis, ESR spectrum, one-dimensional (1D) infrared spectroscopy and two-dimensional (2D) correlation infrared spectroscopy under thermal and magnetism perturbation. Crystal data for the compound 1: orthorhombic system, space group Pnma, a = 14.580(3)A, b = 21.073(4)A, c = 16.664(3)A, Z = 4. It consists of the Mo-Cu building-blocks [Cu(imi)(4)](2)[P(2)Mo(5)O(23)](2-), protonated imidazole cations and water molecules. In the Mo-Cu building-blocks, [Mo(5)P(2)O(23)](6-) clusters are linked by {Cu(imi)(4)}(2+) group to form a two-dimension parallelogram griddling structure. From the 2D IR correlation spectroscopy analyses, it is discovered that the intensity changes of Mo=O and P-O band are sensitive to the temperature variation, whereas the Mo-O bond linking to Cu(2+) can be remarkably affected by the magnetism variation. Furthermore, the intensity changes of P-O bands occur prior to that of the Mo=O band during the temperature elevation.

A new noncentrosymmetric three-dimensional tellurite with second-order nonlinear optical property, BaMo2Te2O11(H2O), was synthesized by the hydrothermal reaction of Ba(OH)2, TeO2 and MoO3. It is characterized by single-crystal X-ray diffraction and spectral properties. The compound contains {Mo(1)Mo(2)O10}n infinite spiral chains, which are linked into infinite anionic layers along ab plane by Te(1)O5 and Te(2)O4 polyhedra. Ba2+ cations are intercalated between the layers. Energy band of the compound is calculated and analyzed, the band gap is 3.23 eV, it indicates the solid-state compound of BaMo2Te2O11(H2O) is an insulator and the value is consistent well with the experimental value of 3.18 eV.

A novel compound, (4,4′-Hbpy)2(K2Mo8O26) 1 (bpy = bipydine), was synthesized by hydrothermal method and characterized by X-ray single analysis, thermalgravimetric analysis, one-dimensional (1D) infrared spectroscopy and two-dimensional (2D) correlation infrared spectroscopy under thermal perturbation. In the compound 1, the [Mo8O26] units link to potassium ions to form layer structure, and the protonated 4,4′-bpy are linked to chains by hydrogen bonds. The 2D IR correlation spectroscopy study indicates that the intensity changes of Mo O, N H and C C stretching vibration are sensitive to the temperature variation, and the intensity changes of asymmetry stretching vibration of the terminal Mo O occur prior to that of terminal Mo O linked by K atom. At the same time, the peaks of asymmetry stretching vibrations of the terminal Mo O and the stretching vibrations of N H split into two peaks respectively in 2D IR correlation spectroscopy.

A novel polyoxometalate (POM) Na2(H2en)2{(VO)10[B14O30(OH)2]2}{Mn4(C2O4) [B2O4(OH)2]2}Mn(H2O)2·(H3O)12(H2O)19 1 (en=ethylenediamine), which is a layer-like transition metal (TM) oxalate templated polyoxovanadium borate, has been synthesized under hydrothermal conditions and characterized by EPR, elemental analysis, thermal analysis, single crystal X-ray diffraction and 2D IR correlation spectroscopy studies, respectively. This compound crystallized in the triclinic space group P 1 ¯ with a = 14.3842 ( 4 ) A , b = 14.6837 ( 3 ) A , c = 15.8681 ( 4 ) A , α = 64.48 ( 1 ) ° , β = 64.68 ( 1 ) ° , γ = 63.93 ( 1 ) ° , V = 2596.80 ( 11 ) A 3 and Z = 2 . The cluster anion with an open central cavity has a central band of ten edge-sharing VO5 square pyramids, which is capped top and bottom by two crown-like polyborate ligands of formula [B14O30(OH)2]20−. There is a fragment of {Mn4(C2O4)[B2O4(OH)2]2}2− fixed in the central cavity as a guest part. The cluster units are connected to form a two-dimensional (2D) framework by octahedral Mn(II) and Na+ sites. In addition, we first introduce the generalized 2D correlation spectroscopy to explore the POMs and obtain the dynamic information about structural changes of POMs.

A novel one-dimensional polyoxovanadium borate (H3NCH2CH2NH3)3[(VO)12O4{B8O17(OH)4}2{Na(H2O)}2]·(H3O)2(H2O)6.5 (1) has been synthesized by the hydrothermal method and the structure determined by X-ray crystallography. The structure consists of a continuous contorted V12 ring, constructed from edge-sharing VO5 square pyramids. Two {B8O17(OH)4}14− polyborate chains fill in the cavities formed by the V12 ring. The [(VO)12O4{B8O17(OH)4}2]12− clusters are connected by unusual binuclear Na+ units into 1D chains. The binuclear Na+ units are formed by two neighboring sodium atoms sharing two μ2–O from B–O–B. Each sodium atom is in a distorted octahedral geometry. Other characterizations are also described by elemental analysis, thermal analysis and IR, EPR spectra.

A novel organic–inorganic hybrid compound [(Cu(bIz)2)]2[{Cu(bIz)2}2Mo8O26] (1) has been synthesized from solvothermal reaction of benzimidazole, NaMoO4 and MoO3 with CuCl2·2H2O in H2O/CH3OH solution and characterized by single-crystal X-ray diffraction analysis. Crystallographic data for 1: monoclinic, space group C2/c, a=23.6823(2) A, b=20.2669(5) A, c=16.0220(3) A, β=109.030(1), Z=8, V=7269.8(2) A 3 . The compound consists of a centrosymmetric β-octamolybdate-supported complex anion [{Cu(bIz)2}2Mo8O26]2−, and two bis-bIz coordinated Cu(I) cations. The hydrogen bonds between [{Cu(bIz)2}2Mo8O26]2− anions generate a interesting 1D ladder. TG analysis, UV–Vis spectra and fluorescent spectroscopy of the compound were also studied.

The asymmetric unit of the title compound, (C2H10N2)2[Ti4O4(C6H6NO6)4], consists of halves of two centrosymmetric tetrameric [Ti4O4{N(CH2COO)3}4]4− anions, two [H3N(CH2)2NH3]2+ cations and a disordered mol­ecule of water of crystallization. In the [Ti4O4{N(CH2COO)3}4]4− tetramer, each Ti atom is coord­inated by one nitrilo­tri­acetate ligand and two μ-oxo ligands, so that four titanium and four μ-O atoms form an eight-membered ring. The tetramers are connected by hydrogen bonds with [H3N(CH2)2NH3]2+ cations and with water mol­ecules, leading to an intricate three-dimensional network.

The title compound, (C2H10N2)[MoO10S2], consists of [MoO2(SO4)2]2− chains linked to [H3NCH2CH2NH3]2+ ions, both of which have twofold symmetry. The MoVI atom is octahedrally surrounded by four sulfate O atoms and two terminal O atoms. The μ2-O atom connects the MoO6 octahedra and the SO4 tetrahedra to form a ring, which extends to form a one-dimensional chain along c.

The implantation and growth of metal nanoparticles on graphene nanosheets (GNS) leads directly to severe damage to the regular structure of the graphene sheets, which disrupts the extended pi conjugation, resulting in an impaired device performance. In this paper, we describe a facile approach for achieving the lossless formation of graphene composite decorated with tiny cadmium sulfide quantum dots (QDs) with excellent nonlinear optical properties by using benzyl mercaptan (BM) as the interlinker. The mercapto substituent of BM binds to the CdS QDs during their nucleation and growth process, and then the phenyl comes into contact with the GNS via the pi-pi stacking interaction. Using this strategy, CdS QDs with an average diameter of 3 nm are uniformly dispersed over the surface of graphene, and the resulting QD-graphene composite exhibits excellent optical limiting properties, mainly contributed by nonlinear scattering and nonlinear absorption, upon both 532 and 1064 nm excitations, in the nanosecond laser pulse regime.

The title compound, (C2H10N2)2[Mo5O15(HPO4)2], consists of [Mo5O15(HPO4)2]4− clusters with one Mo and one O atom located on a twofold rotation axis linked to [H3N(CH2)2NH3]2+ ions. The [Mo5O15(HPO4)2]4− anion consists of five edge-sharing or corner-sharing MoO6 octahedra, which adopt distorted octahedral geometry, and two corner-sharing PO4 tetrahedra. The anion clusters are connected by hydrogen bonds with [H3N(CH2)2NH3]2+.