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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 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.