Structural characterization,thermal, ac conductivity and dielectric properties of (C7H12N2)2[SnCl6]Cl2·1.5H2O

(C₇H₁₂N₂)₂[SnCl₆]Cl₂·1.5H₂O is crystallized at room temperature in the monoclinic system (space group P2₁/n). The isolated molecules form organic and inorganic layers parallel to the (a, b) plane and alternate along the c-axis. The inorganic layer is built up by isolated SnCl₆ octahedrons. Besides, the organic layer is formed by 2,4-diammonium toluene cations, between which the spaces are filled with free Cl^? ions and water molecules. The crystal packing is governed by means of the ionic N—H···Cl and Ow—H···Cl hydrogen bonds, forming a three-dimensional network. The thermal study of this compound is reported, revealing two phase transitions around 360(±3) and 412(±3) K. The electrical and dielectric measurements were reported, confirming the transition temperatures detected in the differential scanning calorimetry (DSC). The frequency dependence of ac conductivity at different temperatures indicates that the correlated barrier hopping (CBH) model is the probable mechanism for the ac conduction behavior.     

Synthesis, Crystal Structure and Luminescent Property of Complex [Tb0.1Gd0.9(TPTZ)(H2O)6]Cl3·3H2O

The complex [Tb_0.1Gd_0.9(TPTZ)(H₂O)₆]Cl₃·3H₂O was prepared through the reaction of 2,4,6-tris-(2-pyridyl)-1,3,5-triazine (TPTZ) with TbCl₃:GdCl₃ (0.1:0.9) in absolute ethanol at room temperature. Single crystal X-ray diffraction revealed that the metal atom is nine-coordinated with three nitrogen atoms from one TPTZ ligand and six oxygen atoms from six water molecules. The complex emits intense green fluorescence under ultraviolet light. The luminescence peaks correspond to the characteristic emission ⁵D₄→⁷F_J (J = 3–6) transitions of the Tb³⁺ ion.     

DFT(B3LYP/LanL2DZ), non-linear optical and electrical studies of a new hybrid compound: [C6H10(NH3)2]CoCl4·H2O

A new organic-inorganic material [C₆H₁₀(NH₃)₂]CoCl₄·H₂O was reported. The title compound was synthesized at room temperature by slow evaporation and then characterized by a single X-ray diffraction, spectroscopic measurements, thermal analysis and dielectric technique. It crystallizes in the non-centrosymmetric space group Pna2₁ with the following unit cell parameters: a=12.5328(1) Å, b=9.0908(1) Å, c=11.7440(1) and α=β=γ=90°. The structure can be described by the alternation of two different cationic-anionic layers. It consists of isolated H₂O, isolated [CoCl₄]²⁻ tetrahedral anions and diammoniumcyclohexane [C₆H₁₀(NH₃)₂]²⁺ cations, which are connected via N–H…Cl, N–H…O and O–H…N hydrogen bonds. The Hirshfeld surface analysis was conducted to investigate intermolecular interactions and associated 2D fingerprint plots, revealing the relative contribution of these interactions in the crystal structure quantitatively. Theoretical calculations were performed using DFT/B3LYP/LanL2DZ method for studying the molecular structure and vibrational spectra and especially to examine the non-linear optical behavior of the compound. Solid state ¹³C NMR spectrum shows three signals correspond to three different carbon environments. Thermal analysis discloses a phase transition at the temperature 315 K and the evaporation of water molecule at 327 K. A detailed dielectric study was reported and shows a good agreement with thermal measurements.     

配合物Eu(C5H8NO3)2(C3H5N2)2Cl3·3H2O光致发光性能

利用OPO激光激发光谱和三维荧光光谱研究了配合物Eu(C5H8NO3)2(C3H5N2)2Cl3·3H2O固体粉末在不同激发光源下的荧光特性,测试了不同浓度配合物水溶液的荧光光谱.固体荧光结果显示该配合物具有很好的荧光性能,当激发光波长为320-400nm时,产生波长分别为400-500nm、580-620nm及690-710nm的三个荧光区;当激发光波长为700-880nm时产生峰值为450nm升频转换荧光,激发光波长为700-800nm时产生峰值分别为590nm和615nm的升频转换荧光.溶液荧光结果表明在10-4-10-2mol/L浓度范围内荧光强度与溶液浓度呈正相关.对其可能的发光机制进行了探讨.     

Structure and magnetotransport properties of the new quasi-two-dimensional molecular metal β″-(BEDT-TTF)4H3O[Fe(C2O4)3] · C6H4Cl2

The β″-(BEDT-TTF)₄A^I[M^III(C₂O₄)₃] · G(A^I=NH ₄ ⁺ , H₃O⁺, K⁺, Rb⁺; M^III=Fe, Cr; G = “guest” solvent molecule) family of layered molecular conductors with magnetic metal oxalate anions exhibits a pronounced dependence of the conducting properties on the type of neutral solvent molecules introduced into the complex anion layer. A new organic dichlorobenzene (C₆H₄Cl₂)-containing conductor of this family, namely, β″-(BEDT-TTF)₄H₃O[Fe(C₂O₄)₃] · C₆H₄Cl₂, is synthesized. The structure of the synthesized single crystals studied by X-ray diffraction is characterized by the following parameters: a = 10.421(1) Å, b= 19.991(2) Å, c= 35.441(3) Å, β = 92.87(1)°, V= 7374(1) ų, space groupC2/c, and Z = 4. In the temperature range 0.5&;2-300 K, the conductivity of the crystals is metallic without changing into a superconducting state. The magnetotransport properties of the crystals are examined in magnetic fields up to 17 T at T = 0.5 K. In fields higher than 10 T, Shubnikov-de Haas oscillations are detected, and the Fourier spectrum of these oscillations contains two frequencies with maximum amplitudes of about 80 and 375 T. The experimental results are compared with the related data obtained for other phases of this family. The possible structural mechanisms of the effect of a guest solvent molecule on the transport properties of the β″-(BEDT-TTF)₄A^I[M^III(C₂O₄)₃] · G crystals are analyzed.     

[Co (C5O2H8)2]·H3COH的 水热合成和晶体结构

合成了[Co (C5O2H8)2]·H3COH金属配合物,通过X射线衍射仪测得配合物[Co(C5O2HD2]·H3COH的晶体结构.晶体属于单斜晶系,空间群为P2 (1)/c,其晶胞参数为a=0.93325(16)nm,b=1.15015(16)nm,c=1.30029(16)nm,α=90.00°,γ=90.00°,...     

50-5000 eV电子被C4H8O, C5H10O2, C6H5CH3和C4H8O2散射的总截面

使用电子被C, H和O原子散射总截面的实验数据, 利用修正后的可加性规则计算了能量为50-5000 eV的电子被4个复杂大分子C4H8O, C5H10O2, C6H5CH3和C4H8O2散射的总截面, 并将计算结果与实验结果及其他理论计算结果进行了比较. 结果表明, 即使是在几十电子伏的入射能量下, 修正后的可加性规则计算出的总截面依然能与实验结果符合很好, 而使用未修正的可加性规则进行计算, 即使是在几百电子伏的入射能量下得到的总截面仍偏离实验值较远. 分析表明, 未修正的可加性规则计算得到的总截面在中低能区过大、随电子入射能量的增加而衰减太快的问题是由可加性规则本身引起的, 其实质是未考虑低能下分子内原子间的相互屏蔽对散射总截面的计算所带来的影响.     

Low-temperature x-ray diffraction studies of the crystallographic parameters and thermal expansion of (CH3)2NH2Al(SO4)2 · 6H2O crystals

The a, b, c, and β crystallographic parameters of the (CH₃)₂NH₂Al(SO₄)₂ · 6H₂O crystal (DMAAS) have been measured by x-ray diffraction in the 90–300-K temperature range. The thermal expansion coefficients along the principal crystallographic axes α_a, α_b, and α_c have been determined. It was shown that, as the temperature is increased, the parameter α decreases and b increases, whereas c decreases for T<T _c (where T _c is the transition temperature) and increases for T>T _c, so that one observes a minimum in the c=f(T) curve in the region of the phase transition (PT) temperature T _c ～ 152 K. The thermal expansion coefficients α_a, α_b, and α_c vary in a complicated manner with increasing temperature, more specifically, α_a and α_c assume negative values at low temperatures, and the α_a=f(T), α_b=f(T), and α_c=f(T) curves exhibit anomalies at the PT point. The crystal has been found to be substantially anisotropic in thermal expansion.     

MnV2O6⋅V2O5 cross-like nanobelt arrays: synthesis, characterization and photocatalytic properties

Single-crystalline MnV₂O₆?V₂O₅ cross-like nanobelt arrays were successfully synthesized by hydrothermal reaction. The products were characterized by X-ray diffraction, transmission electron microscopy and high-resolution transmission electron microscopy. The effects of the reaction conditions such as pH, V⁵⁺/Mn²⁺ ratio, carboxymethyl cellulose concentration and reaction time on the morphology of the products were studied. The band gap of the as-prepared products was calculated via diffuse reflectance spectral analysis and their activity of photocatalytic oxidation was evaluated by photodegradation of methylene blue under visible-light irradiation. The results showed that the degradation efficiency of methylene blue catalyzed by the calcinated products is remarkably enhanced due to Mn doping, suggesting that MnV₂O₆?V₂O₅ cross-like nanobelt arrays are a good candidate for visible-light-driven photocatalysts.     

Electron paramagnetic resonance of quasi-one-dimensional crystal [Nd2(Cl3COO)6(H2O)3]n · nH2O

A quasi-one-dimensional single crystal of [Nd₂(Cl₃COO)₆(H₂O)₃]_n · nH₂O in which chains are built up of two alternating neodymium-ion dimer fragments is studied by the EPR technique. It is found that anisotropic interactions between neodymium ions in a chain are responsible for the complex shape of the EPR spectrum. Two groups of EPR signals are distinguished in the spectrum. Each group corresponds to one of the chain dimers disturbed by the interaction with neighbors in the chain. The shape of the EPR spectra is interpreted as a superposition of the spectra of chain fragments which have different lengths and are formed by the alternating magnetic triplet and nonmagnetic singlet states in the chain. Consideration is given to two cases when two alternating dimer fragments are either equivalent or nonequivalent to each other. It is shown that the spectral shape is primarily determined by the superposition of the spectra of an isolated triplet state (S=1), two interacting triplet states, and three interacting triplet states whose weighting contributions differ for the above two cases. The tensors of the anisotropic spin-spin interaction are determined, and the contribution from the isotropic component of the interaction is estimated.     

The 4 A 2→2 E transitions of 2[Cr(en)3Cl3]KCl. 6H2O in strong magnetic fields

The Zeeman effect of the R absorption lines for the pure compound 2[Cr(en)₃Cl₃]KCl.6H₂O has been measured photographically, using a strong pulsed magnet with fields of up to 200 000 gauss at 77 K. The results indicate g _∥ (⁴ A ₂) = 1·82 , g _⊥(⁴ A ₂) = 1·90 with g _∥(ē) = -1·82 and g _∥ (2ā) = 1·82. The uncertainties are of the order of ± 0·05.     

混配配合物[Co(cpida)(C7H5N2)2]·C7H5N2·5H2O

在溶液中用N-(邻苯甲酸基)-亚氨基二乙酸、苯并咪唑和Co(Ac)2·4H2O进行自组装合成了标题三元金属混配配合物.用元素分析、红外光谱、单晶衍射对配合物的组成和结构进行了表征,确定配体N-(邻苯甲酸基)-亚氨基二乙酸中的3个羧基为单齿形式与中心金属钴离子配位.     

Influence of isomorphous substitution of metal ion on the low-frequency dielectric dispersion in NH2(CH3)2Al1−xCrx(SO4)2⋅6H2O ferroelectrics

This paper is devoted to the study of the influence of metal ion isomorphous substitution on the ferroelastic-ferroelectric phase transition and dispersion caused by the motion of domain walls in dimethylammonium metal sulfate hexahydrate DMAAl_1?xCr_xS ferroelectric crystals (x = 0, 0.065, 0.2). It is shown that such a substitution significantly changes the phase transition temperature and parameters of the dielectric dispersion. These changes are explained in terms of interaction between the metal-hydrate complexes and DMA groups that carry the dipole moment and due to this they are responsible for the phase transitions and motion of the domain walls.     

Diode laser measurements of air and nitrogen broadening in the ν2 bands of HDO,H216O,and H218O

Pressure-broadening coefficients for several rotation-vibration lines in the ν₂ bands of HDO, H₂¹⁶O, and H₂¹⁸O have been determined from laboratory spectra recorded in the 1260- to 1360-cm⁻¹ region with a tunable diode laser spectrometer system. Air and nitrogen were used as the broadening gases and, for all the measured transitions, the nitrogen-broadened half-widths were found to be consistently larger than the corresponding air-broadened half-widths by about 12%. The results have been compared to previously published values when appropriate.     

Phase transition studies in CoSiF6·6H2O and Co1−xZnxSiF6·6H2O by Mn(II) EPR

Phase transition studies on single crystals of CoSiF₆·6H₂O and Co_1−xZn_xSiF₆·6H₂O (x = 0.082, 0.182, 0.248) using Mn(II) EPR at X-band were carried out in the temperature range 10–300 K. Phase transitions with considerable thermal hysteresis have been detected in CoSiF₆·6H₂O and Co_1−xZn_xSiF₆·OH₂O (x = 0.082, 0.182). In CoSiF₆·6H₂O, the transition temperatures during cooling (T^c_c) and during heating (T^h_c) were found to be considerably less than those obtained previously from magnetic anisotropy experiments, i.e. 230 and 246 K as against 246 and 259 K. These characteristic temperatures for the dilute crystals having x = 0.082 and 0.182 were 205, 218 K and 175, 185 K, respectively. It is thus evident that magnetic dilution with zinc causes a progressive reduction in the transition temperatures as well as in the thermal hysteresis. The phase transition manifests itself in a large discontinuous increase in the Mn(II) zero-field splitting parameter (D), i.e. from −187 ± 1 G to −290 ± 1 G, in these crystals. The hyperfine coefficient (A) also increases discontinuously from 99 ± 1 G to 102 ± 1 G at T_c. In the dilute crystal with x = 0.248 a very slow continuous decrease in D and practically no change in A have been detected with a lowering of the temperature. A small temperature independent positive g-shift (g = 2.020 ± 0.005) has been observed in all the crystals studied. The spin-lattice relaxation time (T₁) of the Co(II) ion in CoSiF₆·6H₂O at different temperatures, both above and below T_c, has been estimated from the observed Mn(II) hyperfine linewidth. A discontinuous change in T₁ at T_c has been observed. Analysis of the temperature dependence of the linewidth has further revealed that a two-level Orbach process describes well the thermal behaviour of the spin-lattice relaxation of the Co(II) ions in these crystals. The location of the first excited level in CoSiF₆·6H₂O determined from such studies at temperatures both above and below T_c has been examined in the light of the ligand field energy scheme of the Co(II) ion in an octahedral field. It is concluded that the phase transition in this crystal is probably accompanied by a change in sign of the axial field parameter (Δ).     

Correlation of dielectric properties,Raman spectra and calorimetric measurements of β-cyclodextrin-polyiodide complexes (β-cyclodextrin)2 ·BaI7 ·11H2O and (β-cyclodextrin)2 ·CdI7·15H2O

The frequency and temperature dependence of real and imaginary parts of the dielectric constant (ε′,?ε″), the phase shift (?) and the ac-conductivity (σ) of polycrystalline complexes (β-CD)₂·BaI₇·11H₂O and (β-CD)₂·CdI₇·15H₂O (β-CD?=?β-cyclodextrin) has been investigated over the frequency and temperature ranges 0–100?kHz and 140–420?K in combination with their Raman spectra, DSC traces and XRD patterns. The ε′(T), ε″(T) and ?(T) values at frequency 300?Hz in the range T<330?K show two sigmoids, two bell-shaped curves and two minima respectively revealing the existence of two kinds of water molecule, the tightly bound and the easily movable. Both complexes show the transition of normal hydrogen bonds to flip-flop type at 201?K. In the β-Ba complex most of the eleven water molecules remain tightly bound and only a small number of them are easily movable. On the contrary, in the β-Cd case the tightly bound water molecules are transformed gradually to easily movable. Their DSC traces show endothermic peaks with onset temperatures 118°C, 128°C for β-Ba and 106°C, 123°C, 131°C for β-Cd. The peaks 118°C, 106°C, 123°C are related to the easily movable and the tightly bound water molecules, while the peaks at 128°C, 131°C are caused by the sublimation of iodine. The activation energy of Ba²⁺ ions is 0.52?eV when all the water molecules exist in the sample and 0.99?eV when the easily movable water molecules have been removed. In the case of β-Cd the corresponding activation energies are 0.57?eV and 0.33?eV. The Raman peaks at 179?cm^?1, 170?cm^?1 and 165–166?cm^?1 are due to the charge transfer interactions in the polyiodide chains.     

[Fe3O（Ala）6（H2O）3]（ClO4）7和[Fe3O（Gly）6（H2O）3]（NO3）7·3H2O的顺原共振谱及变温磁化率研究

本文通过对[Fe 3O(Ala) 6(H 2O) 3](ClO 4) 7和[Fe 3O(Gly) 6(H 2O) 3](NO 3) 7·3H 2O的ESR谱的解析及变温磁化率的研究,得出它们的ESR谱具有各向同性的特点;朗德因子分别为2.019和1.997;两种配合物中铁离子间有反铁磁相互作用.     

Pressure dependence of vibrational Raman scattering of narrow-band, 248-nm, laser light by H2, N2, O2, CO2, CH4, C2H6, and C3H8 as high as 97 bar

We have previously investigated methods that image high-pressure processes such as combustion inside automobile cylinders and aircraft engines, or chemical phenomena in supercritical fluids. Here we show that vibrational Raman scattering can simply obtain, quantitatively, densities of some combustion-relevant molecules. We use narrow-band KrF excimer-laser light. Measurements for H₂, N₂, O₂, CO₂, and CH₄ are in the pressure range from 1 to 60 bar, whereas those for C₂H₆ and C₃H₈ are up to their respective vapor pressures. All these species are at ambient temperature. Additional measurements are described for CO₂ up to 96.8 bar and 318 K, where CO₂ is a supercritical fluid. The O₂ measurements are complicated by a photochemical formation of O₃; those in supercritical CO₂ by drastic bending of the laser beam within this medium. We show that, for each gas, the Raman signal is directly proportional to gas density, thereby making quantitative analysis particularly convenient. For each species, we present an estimate of its Raman cross-section relative to that of N₂. However we recommend that future diagnostics users calibrate their own systems for relative species sensitivity. Received: 23 December 1999 / Revised version: 6 June 2000 / Published online: 20 September 2000