Synthesis,Structure, and Characterization of a Microporous Metal‐Organic Framework with PtS Topology

The microporous metal‐organic framework Cd₂(ABTC)(H₂O)(DMA)₂ · H₂O · 3DMA ( 1 ) (H₄ABTC = 3, 3′,5, 5′‐azobenzenetetracarboxylic acid; DMA = N,N′‐dimethylacetamide) was prepared by solvothermal reaction and characterized. X‐ray structure analysis revealed that compound 1 is a three‐dimensional (3D) open framework with 2D channels. The topology is based on a PtS net, constructed of 4‐connected rectangular ABTC^4– units with 4‐connected tetrahedral dinuclear Cd₂(CO₂)₄(H₂O)(DMA)₂ secondary building units (SBUs). The solid‐state excitation‐emission spectra showed that the strongest emission peak is at 403 nm upon excitation at λ = 287 nm.     

Syntheses,Structures, and Photoluminescence Properties of a Series of 3D Zn‐Ln Heterometallic Complexes with 2,3‐Pyrazine Dicarboxylic Acid as a Bridging Ligand

A series of 3D d–f heterometallic coordination polymers, {[Ln₂Zn(Pzdc)₄(H₂O)₆] · 2H₂O}_n [Ln = La ( 1 ), Pr ( 2 ), Nd ( 3 ), Sm ( 4 ), Eu ( 5 ), Gd ( 6 ), Tb ( 7 ), Dy ( 8 )] (H₂Pzdc = 2,3‐pyrazine dicarboxylic acid), were synthesized by one‐pot reactions under hydrothermal conditions. X‐ray crystallographical analysis and powder X‐ray diffraction analysis reveal that the complexes 1 – 8 are isostructural and adopt a multi‐parallel quadrilateral channel network structure with {4.6 · 2}₂{4 · 2.6 · 2.8 · 2}{6 · 3}2{6 · 5.8}₂ topology, in which the central Ln^III ion is nine‐coordinate by four oxygen atoms and two nitrogen atoms from four ligands and three oxygen atoms from three coordinated H₂O molecules and the central Zn^II ion is six‐coordinate by four oxygen atoms and two nitrogen atoms from four ligands. Moreover, the photophysical properties related to the electronic transition for complexes 4 , 5 , 7 , and 8 were investigated by the excitation and emission spectra as well as the emission lifetimes.     

Synthesis, Crystal Structure and Optical Properties of Europium Trifluoroacetate Complexes with 1,10-Phenanthroline and 2,2-Bipyridine

Two europium trifluoroacetate complexes, Eu(CF₃COO)₃·phen ( 1 ) and Eu(CF₃COO)₃·bpy ( 2 ) (where phen=1,10‐phenanthroline, bpy=2,2′‐bipyridine), were synthesized and characterized by elemental analysis, Fourier transform infrared spectroscopy (FT‐IR), photoluminescence (PL) spectroscopy and thermogravimetric analysis (TA). Single‐crystal X‐ray structure has been determined for the complex [Eu₂(CF₃COO)₆·(phen)₃·(H₂O)₂]·EtOH. The crystal structure of [Eu₂(CF₃COO)₆·(phen)₃·(H₂O)₂]·EtOH shows that two different coordination styles with europium ions coexist in the same crystal and have entirely different coordination geometries and numbers. This crystal can be considered as an 1:1 adduct of [Eu(CF₃COO)₃·(Phen)₂·H₂O]·EtOH (9‐coordination part) and Eu(CF₃COO)₃·phen·H₂O (8‐coordination part). The excitation spectra of the two complexes demonstrate that the energy collected by "antenna ligands" is transferred to Eu³⁺ ions efficiently. The room‐temperature PL spectra of the complexes are composed of the typical Eu³⁺ ions red emission, due to transitions between ⁵D₀→⁷F_J(J=0→4). The lifetimes of ⁵D₀ of Eu³⁺ in the complexes were examined using time‐resolved spectroscopic analysis, and the lifetime values of Eu(CF₃COO)₃·phen and Eu(CF₃COO)₃·bpy were fitting with bi‐exponential (2987 and 353 µs) and monoexponential (3191 µs) curves, respectively. In order to elucidate the energy transfer process of the europium complexes, the energy levels of the relevant electronic states had been estimated. The thermal analyses indicate that they are all quite stable to heat.     

Triboluminescence of lanthanide acetylacetonates

Triboluminescence of Ln(acac)₃·H₂O (Ln = Tb, Eu, Pr, Ce, Gd) was found. The UV radiation was detected for the first time as narrow bands caused by the emission of the adsorbed N₂* molecules (transitions ³∏_u → ³∏_g) in the study of triboluminescence of lanthanide compounds. The emission of Ln³⁺* (ionic triboluminescence) was observed only for Tb³⁺* (λ_max/nm: 490 (⁵D₄-⁷F₆), 545 (⁵D₄-⁷F₅), 580 (⁵D₄-⁷F₄)) and Eu³⁺* (λ?max/nm: 613, 614 (⁵D₂-⁷F₃)). The generation of N₂* occurs due to the energy of electric fields appeared upon the destruction of crystalline samples of Ln(acac)₃·H₂O. The Tb³⁺* and Eu³⁺* ions are formed due to the energy transfer from the triplet level of the ligand (acacT₁), which is excited by the light emitted from the N₂* molecule.     

Cobalt(II) and cobalt(III) coordination polymers constructed from flexible bis-imidazole and polycarboxyl co-ligands: syntheses,crystal structures and properties

Two metal coordination polymers, namely {[Co(1,3-BIP)(OBA)]·0.5H₂O}_n (SNUT-1) and [Co₂(µ-η¹:η¹-O₂)(1,3-BIP)₂(PMA)]_n (SNUT-2), where 1,3-BIP?=?1,3-bis(imidazol)propane, H₂OBA?=?4,4′-oxybis(benzoate) and H₄PMA?=?benzene-1,2,4,5-tetracarboxylic acid, were prepared by hydrothermal methods. Single-crystal X-ray analysis revealed that the structure of SNUT-1 consists of a 3D?→?3D twofold interpenetrating network that can be described as a 4-connected uninodal net with (6⁵·8) topology. The structure of SNUT-2 consists of a 3D framework which can be described as a (4,5)-connected binodal net with (4²·6³·8⁴·10) (3³·4²·5) topology. The gas adsorption properties of SNUT-1 and photocatalytic activity of SNUT-2 for the degradation of Rhodamine B have been explored.

     

Polarized Raman spectra of lanthanum ethylsulfate nonahydrate and potassium ethylsulfate crystals

The polarized Raman spectra of La(C₂H₅SO₄)₃·9H₂O, La(C₂H₅SO₄)₃·9D₂O and KC₂H₅SO₄ crystals have been observed from 30 to 4000 cm⁻¹ at room temperature. The observed bands have experimentally been classified into each Raman-active symmetry species. From the far-infrared spectra from 30 to 300cm⁻¹ of La(C₂H₅SO₄)₃· 9H₂O, the absorption bands of the infrared-active E_1u species have also been obtained. The vibrational assignment for the ethylsulfate group has been made by comparing the spectra of La(C₂H₅SO₄)₃·9H₂O and La(C₂H₅SO₄)₃·9D₂O with those of KC₂H₅SO₄ and using a group-theoretical consideration.     

Anisotropic contributions in the ligand polarization model for the f-f transition probabilities of Eu(III) complexes

The intensities of the ΔM = ± 1 component of the ⁷f_o→ ⁵D₂ transition in D₃ complexes containing the [ EuO₉] cluster, and of other d-d or f-f transitions in D₃ complexes with the yz- and xz-components of the electric quadrupole as the leading moment, are found to be dependent upon the polarizability anisotropy of the ligands. The expectation is supported by determinations of the single-crystal absorption intensities of Na₃ [Eu(diglycollate)₃]·2NaClO₄·6H₂O and [Eu(H₂O)₉] (C₂H₅SO₄)₃.     

Study of spectroscopic properties of Europium (III) Tris(β-diketonate) complex and α-Cyclodextrin in aqueous medium

The solubilization of an europium (III) β-diketonate chelate in aqueous medium and the changes in its photophysical properties upon its inclusion into an α-cyclodextrin hydrophobic cavity are described. The complex [Eu(tta)₃·(H₂O)₂] (tta = 4,4,4-trifluoro-1-(thiophen-2-yl)butane-1,3-dione) was synthesized, characterized, and incorporated into the hydrophobic cavity by stirring in an α-cyclodextrin aqueous solution. The inclusion was confirmed by ¹H NMR, and the stoichiometry of association was obtained by the Job method. The maximum in the excitation spectrum of the α-CD inclusion compound in aqueous solution was shifted 28 nm compared with the maximum of non α-CD complex. The emission spectrum of the association is similar to that of the free solid complex and displays the characteristic ⁵D₀ → ⁷F_0-4 Eu³⁺ transitions.     

Metal(II) Complexes Based on Imidazo[4, 5‐f]‐1, 10‐phenanthroline and Bridging Dicarboxylato Ligands: Synthesis,Characterization and Photoluminescence

Eight metal(II) complexes based on imidazo[4, 5‐f]‐1, 10‐phenanthroline (HIMP) and bridging dicarboxylato ligands such as 4, 4′‐biphenyldicarboxylic acid (H₂BPDC), 1, 4‐benzenedicarboxylic acid (H₂BDC), thiophene‐2, 5‐dicarboxylic acid (H₂TDC), and 2, 6‐naphthalenedicarboxylic acid (H₂NDC) were hydrothermally synthesized and structurally characterized by single‐crystal X‐ray diffraction. Complexes 1 , 3 , 6 , and 7 are molecular dinuclear metal complexes. Complexes 2 , 4 , and 5 exhibit chain‐like structures. Compound 8 shows a novel 3D architecture, in which Zn^II dimers are connected by four NDC^2– anions. In the metal(II) complexes, HIMP exhibits a similar chelating coordination mode. Different π ··· π stacking interactions are observed in the complexes. The emission of HIMP is completely quenched in complexes 1 – 4 due to the strong π ··· π stacking interactions in the structures. Complexes 5 – 8 exhibit different photoluminescence properties. Firstly, we quantitatively investigated the effect of the strong HIMP–HIMP stacking interactions on the emission quenching of HIMP in the metal complexes. It was found that a higher extent of π ··· π stacking interactions in the complexes resulted in a higher extent of the emission quenching of HIMP. The introduction of aromatic conjugated carboxylate groups into metal(II)‐HIMP complexes changed the extent of the strong π ··· π stacking interactions in the structures and thus the photoluminescence properties of the complexes.     

Studies of the hydrated oxonium radical H3O·(H2O)n and the ammoniated ammonium radical NH4·(NH3)n by neutralized ion beam techniques

Neutralized ion beam studies of the clusters NH₄·(NH₃)_n and H₃O·(H₂O)_n,n = 0–3, and their fully deuterated analogs are presented. Stabilization of the hypervalent monomer radicals is found to accompany solvation. Cluster stability is found to decrease with increasing size. Reasons for this observation are discussed. Internally excited clusters are found to stabilize efficiently through the sequential loss of structural units (NH₃ or H₂O). The mixed isotopic dimer clusters (D₂¹⁸O)·D·(D₂¹⁶O) and (HDO)·D·(D₂O) are also investigated. Presence of the D₃¹⁶O radical structural unit is found to be crucial to dimer stability. This is consistent with the results of earlier investigations involving the monomer which showed the surprising lifetime progression τ(D₃¹⁶O) ≫; τ(D₃¹⁸O) ⩾ τ(H₃¹⁶O).     

Study on the Phase Diagram of CsCl-CeCl3-HCl(11%)-H2O System and the Properties of the Compounds

The equilibrium solubility of CsCl-CeCl3-HCl(11%)-H2O qua-ternary system at 25℃ has been determined by the physicchemical analysis method ,and the phase diagram was plotted, Two new double salts 3CsCl.CeCl3.3H2O and CsCl.CeCl3.4H2O obtained from the complicated system were identified and characterized by XRD,TG-DTA ,DSC,UV and fluorescence spectroscopy, Studies on the fluorescence excitation and emission show that 3CsCl.CeCl3.3H2O and CsCl.CeCl3.4H2O have upconversion luminescence of infrared-visible range,and the upconversion emission intensity increases with the increase of ratio of CeCl3 in CsCl.     

Crystal Structures and Magnetic Properties of Charge-Transfer Salts: Cobaltocenium Bis(cis 1,2-diphenylethene-1,2-dithiolato)metalates (Metal = Ni,Pd, Pt)

Charge-transfer salts [Co(C₅H₅)₂][M(dpt)₂] (M = Ni and Pt; dpt = cis-1,2-diphenylethene-1,2-dithiolate) were synthesized and crystallographically characterized. [Co(C₅H₅)₂][Ni(dpt)2] crystallizes in the monoclinic space group C2/c with a = 25, 607(3) Å, b = 9.4151(11) Å, c = 14.407(4) Å, β = 101.373(22)°, V = 3405.3(10) Å₃ and Z = 4. [Co(C₅H₅)₂][Pt(dpt)₂] belongs to the triclinic space group $ {\rm P}\bar 1 $ with a = 9.4666(11) Å, b = 13.9869(12) Å, c = 14.2652(9) Å, α = 99.983(6)°, β = 90.034(7)°, γ = 109.751(7)°, V = 1747.2(3) ų and Z = 2. Both structures consist of ··· D⁺A^?D⁺A^?D⁺A^? ··· linear chains with the local C₅ axis of the eclipsed [Co(C₅H₅)₂]⁺ cation parallel to the best MS₄ plane of the [M(dpt)₂]^? anion. Magnetic susceptibility measurements show that χ_M T values of the complexes [Co(C₅H₅)₂][M(dpt)₂] (M = Ni, Pd, and Pt) remain nearly constant in the temperature range 15–300 K, but decrease rapidly with further decreasing of temperature, indicating weak antiferromagnetic interactions at low temperatures.     

Collisional de-excitation of the metastableD-states of Ba+ by He,Ne, N2 and H2

The rate constants 〈σ · υ〉 for collisional de-excitation of the metastable 5D states of Ba⁺ ions have been determined in an ion trap experiment. TheD-states are selectively populated by pulsed laser excitation of the 6P _1/2 or 6P _3/2 state and the decay at different background pressures is monitored by the change in fluorescence intensity of the excited ions. From the pressure dependence of the decay constants we calculate the de-excitation rate constants for different collision partners, averaged over the velocity distribution of the trapped ion cloud. For He, Ne, H₂ and N₂ we obtain in the c.m. energy range of 0.1–0.5 eV: 〈σ·υ〉 (He)=3.0±0.2·10^?13cm³/s, 〈σ·υ〉 (Ne)=5.1±0.4·10^?13cm³/s, 〈σ·υ〉 (H₂)=3.7±0.3·10^?11cm³/s, 〈σ·υ〉 (N₂)=4.4±0.3·10^?11cm³/s. The results can be understood qualitatively by a consideration of the ion-atom and ion-molecules interaction potential.     

Supramolecular networks constructed from mono- and bi-nuclear lanthanide complexes with 1,2-phenylenedioxydiacetic acid

[Tb₂(1,2-pdoa)₃ · 6H₂O] · H₂O (1) and [La(1,2-pdoa)(1,2-H₂pdoa)(OH) · H₂O] · 5H₂O (2) (1,2-H₂pdoa = 1,2-phenylenedioxydiacetic acid) have been synthesized and structurally characterized by single crystal X-ray diffraction. Complex 1 is a binuclear molecule in which one 1,2-pdoa ligand is a tetradentate bridge linking two Tb³⁺ ions, the other two 1,2-pdoa ligands bond Tb1³⁺ and Tb1A³⁺ via tetradentate chelating coordination. Tb³⁺ is nine-coordinate by six oxygens of 1,2-pdoa and three waters. Complex 2 is mono-nuclear with La³⁺ ten-coordinate by eight oxygens of two 1,2-pdoa, one hydroxide and one water. 1,2-Pdoa is tetradentate chelating with La³⁺ ion. The packing diagrams of 1 and 2 show supramolecular networks via H-bonds. The fluorescence spectrum of 1 shows characteristic emission of Tb³⁺ with ⁵D₄ → ⁷F_j (j = 6–3) transitions.     

Syntheses,Structures and Magnetic Properties of Three New Extended Iron‐containing Heteropolytungstates

Three new extended iron‐containing heteropolytungstates were synthesized and structurally characterized: K₆[{Fe^II(H₂O)₄}₂(H₂W₁₂O₄₂)]·15H₂O ( 1 ), Na₅[{Fe(H₂O)₃}₂{Fe(H₂O)₄}_0.5(H₂W₁₂O₄₂)]·30H₂O ( 2 ) and (H₃O)⁺₂[{Fe(H₂O)₄Fe(H₂O)₃}₂(H₂W₁₂O₄₂)]·20H₂O ( 3 ). 1 and 3 crystallize in the monoclinic system, space group P2₁/n with a = 14.9967(5), b = 10.3872(3), c = 18.8237(6)Å, β = 93.407(1)°, V = 2927.1(2)ų and D_c = 4.151 g cm^—3 for 1 , and space group P2₁/c with a = 12.1794(4), b = 22.4938(4), c = 11.6941(3) Å, β = 105.731(2)°, V = 3083.7(1) ų, and D_c = 4.043 g cm^—3 for 3 . 2 is triclinic, space group P1¯, with a = 12.121(2), b = 12.426(3), c = 13.247(3)Å, α = 68.33(3), β = 71.33(3), γ = 71.44(3)°, V = 1710.7(6)ų and D_c = 3.735 g cm^—3. In all cases, the structures are based on paradodecatungstate polyoxoanions, which are linked by iron ions into chains, layers and a three‐dimensional structure for 1 , 2 and 3 , respectively.     

Copper(II) and Cadmium(II) Complexes Based on N,N‐Bis(3, 5‐dimethyl‐2‐hydroxybenzyl)‐N‐(2‐pyridylmethyl)amine Ligand: Syntheses,Structures, Magnetic,and Luminescent Properties

The reaction of the aryl‐oxide ligand H₂L [H₂L = N,N‐bis(3, 5‐dimethyl‐2‐hydroxybenzyl)‐N‐(2‐pyridylmethyl)amine] with CuSO₄ · 5H₂O, CuCl₂ · 2H₂O, CuBr₂, CdCl₂ · 2.5H₂O, and Cd(OAc)₂ · 2H₂O, respectively, under hydrothermal conditions gave the complexes [Cu(H₂L¹)₂] · SO₄ · 3CH₃OH ( 1 ), [Cu₂(H₂L²)₂Cl₄] ( 2 ), [Cu₂(H₂L²)₂Br₄] ( 3 ), [Cd₂(HL)₂Cl₂] ( 4 ), and [Cd₂(L)₂(CH₃COOH)₂] · H₂L ( 5 ), where H₂L¹ [H₂L¹ = 2, 4‐dimethyl‐6‐((pyridin‐2‐ylmethylamino)methyl)phenol] and H₂L² [H₂L² = 2‐(2, 4‐dimethyl‐6‐((pyridin‐2‐ylmethylamino)methyl)phenoxy)‐4, 6‐dimethylphenol] were derived from the solvothermal in situ metal/ligand reactions. These complexes were characterized by IR spectroscopy, elementary analysis, and X‐ray diffraction. A low‐temperature magnetic susceptibility measurement for the solid sample of 2 revealed antiferromagnetic interactions between two central copper(II) atoms. The emission property studies for complexes 4 and 5 indicated strong luminescence emission.     

Preparation and crystal data for two trimetaphosphate tellurates: Te(OH)6 · 2Na3P3O9 · 6H2O and Te(OH)6 · K3P3O9 · 2H2O

Te(OH)₆ · 2Na₃P₃O₉ · 6H₂O, is hexagonal (P6₃/m) with a = 11,67(1), c = 12,12(1) Å, Z = 2 and D_x = 2,225 g/cm³. Te(OH)₆ · K₃P₃O₉ · 2H₂O, is monoklin (P2₁/c) with a = 19,61(5), b = 7,456(1), c = 14,84(6) Å, = 108,01(4), Z = 4 and D_x = 2,506 g/cm³. Both compounds are the first examples of phosphate tellurates in which the anion phosphate is condensed to the ring anion P₃O₉. As in phosphate tellurates already described the phosphate groups are independent of the TeO₆ octahedra.     

Optical Spectroscopy of Pr3+ Ion Singly Doped LiLuF4 Single Crystal by Bridgman Method

High quality LiLuF₄ single crystals doped with various Pr³⁺ ions were synthesized by a vertical Bridgman method in completely sealed platinum crucibles. The excitation spectra spans from 420 nm to 500 nm. The prepared single crystals exhibit a blue band at 480 nm (³P₀→³H₄), a green band at 522 nm (³P₁→³H₅), and a red band at 605 nm (¹D₂→³H₄) when excited at 446 nm; their corresponding average lifetimes are 38.5 μs, 37.3 μs, and 36.8 μs, respectively, which are much longer than those in oxide single crystals. The effects of excitation wavelength and doping concentration on emission intensities and chromaticity coordinates are investigated. The optimal Pr³⁺ concentration is confirmed to be 0.5%. The temperature dependent emission shows that the emission intensity constantly decreases with the increase of temperature from 298 K to 443 K due to the enhancement of non-radiative quenching at high temperature. The ³P₀→³H₄ transition is the most vulnerable to temperature, followed by the ³P₁→³H₅ transition and ¹D₂→³H₄ transition.     

An unusually intense effect of the medium acidity on the rate of oxidation of U4+ and the yield of chemiluminescence in aqueous solutions of HClO4 containing K2S2O8

Light emission from aqueous solutions of HClO₄ containing U⁴⁺ and S₂O₈ ^2? has been observed. The emitter of chemiluminescence (CL) is the electron-excited uranyl ion (^*UO ₂ ²⁺ ), the product of U⁴⁺ oxidation. A hundredfold decrease in the HClO₄ concentration (from 1 to 0.01 mol L^?1) results in a 250-fold increase in the reaction rate constant, a 5000-fold increase in the initial CL (from 4·10⁵ to 2·10⁹ photon s^?1), a more than tenfold increase in the CL yield (from 5.6·10^?8 to 1.6·10^?6), and a 200-fold increase in the excitation yield of UO ₂ ²⁺ (from 6·10^?6 to 1.3·10^?3). The kinetic isotope effect of the reaction has been studied. The value for the ratio of the rate constantsk _H/k _D=2.1 has been determined by extrapolation to the 100% degree of deuteration of 0.1M perchloric acid. The peculiarities of the chemiluminescence stage in the reaction of U⁴⁺ oxidation in solutions of potassium persulfate were explained by the participation of the products of hydrolysis of the U⁴⁺ aqua ion (UOH³⁺ and U(OH) ₂ ²⁺ ), whose relative fraction increases as the HClO₄ concentration decreases.     

Crystal Structure and Luminescence of [Eu(TTA)3·DAF]·0.5C7H8 Complex Excited by Visible Light

The non‐ionic europium(III) complex [Eu(TTA)₃·DAF]·0.5C₇H₈ (TTA = 2‐thenoytrifluoroacetonate, DAF = 4, 5‐diazafluoren‐9‐one) was synthesized. The structural determination has been carried out. DAF coordination induces the both excitation spectra in the solid state and solution having a red shift and sensitizes Eu³⁺ luminescence under visible light excitation.