Thermodynamic properties and heat capacities of Co (BTC)1/3 (DMF) (HCOO)

A novel metal organic framework [Co (BTC)_1/3 (DMF) (HCOO)] _n (CoMOF, BTC = 1,3,5-benzene tricarboxylate, DMF = N,N-dimethylformamide) has been synthesized solvothermally and characterized by single crystal X-ray diffraction, X-ray powder diffraction, and FT-IR spectra. The molar heat capacity of the compound was measured by modulated differential scanning calorimetry (MDSC) over the temperature range from 198 to 418 K for the first time. The thermodynamic parameters such as entropy and enthalpy versus 298.15 K based on the above molar heat capacity were calculated. Moreover, a four-step sequential thermal decomposition mechanism for the CoMOF was investigated through the thermogravimetry and mass spectrometer analysis (TG-DTG-MS) from 300 to 800 K. The apparent activation energy of the first decomposition step of the compound was calculated by the Kissinger method using experimental data of TG analysis.     

Molar heat capacities and standard molar enthalpy of formation of pyrimethanil butanedioic salt

A noval anilino-pyrimidine fungicide, pyrimethanil butanedioic salt (C₂₈H₃₂N₆O₄), was synthesized by a chemical reaction of pyrimethanil and butanedioic acid. The low-temperature heat capacities of the compound were measured with an adiabatic calorimeter from 80 to 380 K. The thermodynamic function data relative to 298.15 K were calculated based on the heat capacity fitted curve. The thermal stability of the compound was investigated by TG and DSC. The TG curve shows that pyrimethanil butanedioic salt starts to sublimate at 455.1 K and totally changes into vapor when the temperature reaches 542.5 K with the maximal speed of weight loss at 536.8 K. The melting point, the molar enthalpy (Δ_fus H _m), and entropy (Δ_fus S _m) of fusion were determined from its DSC curves. The constant-volume energy of combustion (Δ_c U _m) of pyrimethanil butanedioic salt was measured by an isoperibol oxygen-bomb combustion calorimeter at T = (298.15 ± 0.001) K. From the Hess thermochemical cycle, the standard molar enthalpy of formation was derived and determined to be Δ_f H _m ^o (pyrimethanil butanedioic salt)=?285.4 ± 5.5 kJ mol^?1.     

Heat capacities and thermodynamic properties of MgNDC

One-three-dimensional metal-organic frameworks Mg_1.5(C₁₂H₆O₄)_1.5(C₃H₇NO)₂ (MgNDC) has been synthesized solvothermally and characterized by single crystal XRD, powder XRD, FT-IR spectra. The low-temperature molar heat capacities of MgNDC were measured by temperature modulated differential scanning calorimetry (TMDSC) over the temperature range from 205 to 470 K for the first time. No phase transition or thermal anomaly was observed in the experimental temperature range. The thermodynamic parameters of MgNDC such as entropy and enthalpy relative to reference temperature of 298.15 K were derived based on the above molar heat capacities data. Moreover, the thermal stability and decomposition of MgNDC was further investigated through thermogravimetry (TG)?Cmass spectrometer (MS). Three stages of mass loss were observed in the TG curve. TG?CMS curve indicated that the oxidative degradation products of MgNDC are mainly H₂O, CO₂, NO, and NO₂.     

The standard molar enthalpy of formation of Ce2(MoO4)3(s) and Sm2(MoO4)3(s) using solution calorimetry

The enthalpies of formations of Ce₂(MoO₄)₃(s) and Sm₂(MoO₄)₃(s) have been measured at 298.15 K using semi adiabatic solution calorimetry. The precipitation reaction between RE(NO₃)₃·6H₂O(s) (R= Ce, Sm) and ammonical solution of Na₂MoO₄(s) was studied. From the enthalpy of precipitation and other required auxiliary data, $ \Updelta_{\text{f}} H_{\text{m}}^{ \circ } \left( { 2 9 8. 1 5 {\text{ K}}} \right) $ Δ f H m ° ( 2 9 8.1 5 K ) of Ce₂(MoO₄)₃(s) and Sm₂(MoO₄)₃(s) have been calculated for the first time as ?4388.7 ± 3.6 and ?4363.4 ± 4.1 kJ mol^?1, respectively. The enthalpy of hydration of anhydrous Ce(NO₃)₃(s) to Ce(NO₃)₃·6H₂O(s) has been calculated. $ \Updelta_{\text{f}} H_{\text{m}}^{ \circ } \left( {{\text{MoO4}}^{ 2- } ,\,{\text{aq}},\, 2 9 8. 1 5 \,{\text{K}}} \right) $ Δ f H m ° ( MoO4 2 ? , aq , 2 9 8.1 5 K ) has also been measured and calculated as ?995.1 kJ mol^?1 from required literature data.     

Crystal Structure, Phase Transition, and Thermodynamic Properties of Bis-dodecylammonium Tetrachlorozincate (C12H25NH3)2ZnCl4(s)

The crystal structure and composition of (C₁₂H₂₅NH₃)₂ZnCl₄(s) were characterized by chemical and elemental analysis, X‐ray powder diffraction technique and X‐ray crystallography. The lattice energy of the title compound was calculated to be U_POT=888.82 kJ·mol^?1. Low temperature heat capacities of the title compound have been measured by a precision automated adiabatic calorimeter over the temperature range from 80 to 403 K. An obvious solid to solid phase transition occurred in the heat capacity curve, and the peak temperature, molar enthalpy and molar entropy of the phase transition of the compound were determined to be T_trs= (364.02±0.03) K, (_trsH_m= (77.567±0.341) kJ·mol^?1, and (_trsS_m= (213.77±1.17) J·K^?1·mol^?1, respectively. Experimental molar heat capacities before and after the phase transition were respectively fitted to two polynomial equations. The smoothed molar heat capacities and fundamental thermodynamic functions of the sample relative to the standard reference temperature 298.15 K were calculated and tabulated at an interval of 5 K.     

Synthesis and thermal behaviors of 1,3-bis(4-aminophenoxy)benzene (TPER) and polyimide based on TPER and pyromellitic dianhydride

1,3-Bis(4-aminophenoxy)benzene (TPER) and poly(amic acid) based on TPER and pyromellitic dianhydride (PMDA) were synthesized. After imidization of the poly(amic acid), polyimide based on TPER and PMDA was obtained. The melting process and the specific heat capacity (C _p) of TPER were examined by DSC and microcalorimetry, respectively. The melting enthalpy, the melting entropy, and the C _p for TPER were obtained. The enthalpy change, the entropy change, and the Gibbs free energy change for TPER were obtained within 283 and 353 K. The thermal decomposition reaction mechanism of the polyimide is classified from the TG–DTG experimental data, and the thermokinetic parameters of the thermal decomposition reaction are E _a = 296.87 kJ mol^?1and log (A/s^?1) = 14.41.     

Heat capacities and thermodynamic properties of one manganese-based MOFs

A metal-organic framework [Mn(4,4′-bipy)(1,3-BDC)] _n (MnMOF, 1,3-BDC = 1,3-benzene dicarboxylate, 4,4′-bipy = 4,4′-bipyridine) has been synthesized hydrothermally and characterized by single crystal XRD and FT-IR spectrum. The low-temperature molar heat capacities of MnMOF were measured by temperature-modulated differential scanning calorimetry for the first time. The thermodynamic parameters such as entropy and enthalpy relative to reference temperature 298.15 K were derived based on the above molar heat capacity data. Moreover, the thermal stability and the decomposition mechanism of MnMOF were investigated by thermogravimetry analysis-mass spectrometer. A two-stage mass loss was observed in air flow. MS curves indicated that the gas products of oxidative degradation were H₂O, CO₂, NO, and NO₂.     

Amino Acid Functionalization of {Ni6PW9}-Based Clusters Under Hydrothermal Conditions

Two novel hexa-nickel(II)-substituted Keggin-type {Ni₆PW₉}-based tungstophosphates [Ni₆(μ ₃-Tris)(en)₃(Pr)(damp)(H₂O)₂(B-α-PW₉O₃₄)]·10H₂O (1) and [Ni₆(μ ₃-Tris)(en)₃(damp)₂(H₂O)₂(B-α-PW₉O₃₄)]·7H₂O (2) (en = ethylenediamine, Pr = CH₃CH₂COO^?, damp = 2-aminoisobutyrate, Tris = pentaerythritol) were hydrothermally synthesized and characterized by IR spectra, elemental analyses, powder X-ray diffraction, thermogravimetric analyses, and single-crystal X-ray diffraction. Crystal data for 1: orthorhombic, Pca2₁, a = 21.6962(7) Å, b = 20.6398(5) Å, c = 14.7825(4) Å, β = 90º, V = 6619.7(3) Å³, Z = 4; for 2: orthorhombic, Pca2₁, a = 21.6978(9) Å, b = 20.6658(7) Å, c = 14.7767(4) Å, β = 90º, V = 6625.9(4) Å³, Z = 4. 1 consists of a {Ni₆(μ ₃-Tris)(en)₃(Pr)(damp)(H₂O)₂}⁹⁺ core and a [B-α-PW₉O₃₄]^9? (PW₉) unit and is covalently functionalized by one Pr and one damp, as well as en and Tris ligands. The structure of 2 is the same to 1 except that the Pr anion in 1 is substituted by the other damp ligand. Most interestingly, 1 contains four kinds of organic ligands, while 2 includes three kinds of organic ligands, which are first observed in polyoxometalate chemistry.     

Determination of heat capacities and thermodynamic properties of two structurally unrelated but isotypic calcium and manganese(II) 2,6-naphthalene dicarboxylate-based MOFs

Two metal-organic frameworks, Ca(2,6-NDC)(DMF) (1) and Mn₃(2,6-NDC)₃(DMF)₄ (2) (where 2,6-NDC = 2,6-naphthalene dicarboxylate and DMF = N,N′-dimethylformamide) have been solvothermally synthesized under optimized conditions and characterized by X-ray powder diffraction, elemental analysis, FT-IR spectroscopy, and TG analysis. The thermal decomposition characteristics were investigated under air atmosphere from 300 to 1,170 K (for 1) and from 300 to 971 K (for 2). The molar heat capacities were measured from 198 to 548 K (for 1) and from 198 to 448 K (for 2) by temperature modulated differential scanning calorimetry (TMDSC) for the first time. The fundamental thermodynamic parameters such as entropy and enthalpy variations with temperature were calculated based on the experimentally determined molar heat capacities.     

配位化合物Zn(Met)3(NO3)2·H2O(s)(Met=L-α-蛋氨酸)的低温热容及标准摩尔生成焓

利用精密绝热热量仪测定了化合物配合物Zn(Met)₃(NO₃)₂·H₂O (s) (Met=L-α-蛋氨酸)在78-371 K温区的摩尔热容. 通过热容曲线解析, 得到了该配合物的起始脱水温度为T_D=325.10 K. 将该温区的摩尔热容实验值用最小二乘法拟合得到了摩尔热容(C_p)对约化温度(T)的多项式方程, 由此计算得到了配合物的舒平热容值和热力学函数值. 基于设计的热化学循环, 选择100 mL of 2 mol·L^-1 HCl为量热溶剂, 利用等温环境溶解-反应热量计, 得到了298.15 K配合物的标准摩尔生成焓为Δ_fH_m⁰[Zn(Met)₃(NO₃)₂·H₂O(s),s]=-(1472.65±0.76) J·mol^-1.     

Thermal behavior and thermodynamic properties of berberine hydrochloride

The low-temperature heat capacities of berberine hydrochloride were measured over the temperature range from 78 to 350 K by an adiabatic calorimeter. The thermodynamic functions H _T ? H _298.15 and S _T ? S _298.15 were derived from the heat capacity data. The results showed that the structure of berberine hydrochloride was stable over the temperature range from 78 to 350 K. The thermal stability of the compound was further tested by DSC and TG measurements. The results were in agreement with those obtained from adiabatic calorimetry experiment. The standard molar enthalpy of formation in the crystalline state of berberine hydrochloride was obtained from the standard molar energies of combustion in oxygen at T = 298.15 K, measured by a rotating-bomb combustion calorimeter.     

Calorimetric study and thermal analysis of [ErY(Ala)4(H2O)8](ClO4)6 (Ala=ALANINE)

A solid complex of rare-earth compounds with alanine, [ErY(Ala)₄(H₂O)₈](ClO₄)₆ (Ala=alanine), was synthesized, and a calorimetric study and thermal analysis for it was performed through adiabatic calorimetry and thermogravimetry. The low-temperature heat capacity of [ErY(Ala)₄(H₂O)₈](ClO₄)₆ was measured with an automated adiabatic precision calorimeter over the temperature range from 78 to 377 K. A solid-solid phase transition was found between 99 and 121 K with a peak temperature at 115.78 k. The enthalpy and entropy of the phase transition was determined to be 1.957 Kj mol^-1, 16.90 j mol^-1 k^-1, respectively. Thermal decomposition of the complex was investigated in the temperature range of 40~550°C by use of the thermogravimetric and differential thermogravimetric (TG/DTG) analysis techniques. The TG/DTG curves showed that the decomposition started from 120 and ended at 430°C, completed in three steps. A possible mechanism of the thermal decomposition was elucidated. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermochemistry on the Complex of Erbium Perchlorate with L-α-Glutamic Acid [Er2（L-Glu）2（H2O）6]（ClO4）4·6H2O（s）

A coordination compound of erbium perchlorate with L-α-glutamic acid, [Er2（Glu）2（H2O）6]（ClO4）4·6H2O（s）, was synthesized. By chemical analysis, elemental analysis, FTIR, TG/DTG, and comparison with relevant literatures, its chemical composition and structure were established. The mechanism of thermal decomposition of the complex was deduced on the basis of the TG/DTG analysis. Low-temperature heat capacities were measured by a precision automated adiabatic calorimeter from 78 to 318 K. An endothermic peak in the heat capacity curve was observed over the temperature region of 290-318 K, which was ascribed to a solid-to-solid phase transition. The temperature Ttrans, the enthalpy △transHm and the entropy △transSm of the phase transition for the compound were determined to be： （308.73±0.45） K, （10.49±0.05） kJ·mol^-1 and （33.9±0.2） J·K^-1·mol^-1. Polynomial equation of heat capacities as a function of the temperature in the region of 78-290 K was fitted by the least square method. Standard molar enthalpies of dissolution of the mixture [2ErCl3·6H2O（s）＋2L-Glu（s）＋6NaClO4·H2O（s）] and the mixture {[Er2（Glu）2（H2O）6]（ClO4）4·6H2O（s）＋6NaCl（s）} in 100 mL of 2 mol·dm^-3 HClO4 as calorimetric solvent, and {2HClO4（1）} in the solution A＇ at T=298.15 K were measured to be, △dHm,1=（31.552±0.026） kJ·mol^-1, △dHm,2 = （41.302±0.034） kJ·mol^-1, and △dHm,3 = （ 14.986 ± 0.064） kJ·mol^-1, respectively. In accordance with Hess law, the standard molar enthalpy of formation of the complex was determined as △fHm-=-（7551.0±2.4） kJ·mol^-1 by using an isoperibol solution-reaction calorimeter and designing a thermochemical cycle.     

稀土高氯酸盐-谷氨酸配合物[Pr2(L-α-Glu)2(ClO4)(H2O)7](ClO4)3•4H2O的低温热容和热化学研究

合成了一种稀土高氯酸盐-谷氨酸配合物. 经TG/DTG、化学和元素分析、FTIR及与相关文献对比, 确定其组成为[Pr₂(L-α-Glu)₂(ClO₄)(H₂O)₇](ClO₄)₃•4H₂O, 纯度为99.0%以上. 利用显微熔点仪分析发现其没有熔点. 在78～370 K温区, 用精密绝热量热仪测量其低温热容, 在285～306 K温区发现一明显吸热峰, 归结为固-固相变过程. 通过相变温区三次重复热容测量, 得到相变温度T_tr、相变焓Δ_trH_m和相变熵Δ_trS_m分别为(297.158±0.280) K, (12.338±0.016) kJ•mol^－1和(41.520±0.156) J•K^－1•mol^－1. 用最小二乘法将非相变温区的热容对温度进行拟合, 得到了热容随温度变化的两个多项式方程. 用此方程进行数值积分, 得到每隔5 K的舒平热容值和相对于273.15 K的热力学函数值. 根据TG/DTG结果, 推测了该配合物的热分解机理. 依据Hess定律, 选择1 mol•dm^－3盐酸为量热溶剂, 利用等温环境溶解-反应量热计, 测定了该配合物的标准摩尔生成焓为: Δ_fH_m⁰＝－(7223.1±2.4) kJ•mol^－1.     

Thermodynamic properties of crystalline phosphate Ba0.5Zr2(PO4)3 over the temperature range from T → 0 to 610 K

The temperature dependence of the heat capacity of crystalline barium zirconium phosphate C _p ^o  = f(T) was measured over the temperature range 6–612 K. The experimental data obtained were used to calculate the standard thermodynamic functions C _p ^o (T), H°(T) ? H°(0), S°(T), G°(T) ? H°(0) over the temperature range from T → 0 to 610 K and standard entropy of formation at 298.15 K. The data on the low-temperature (6 ≤ T/K ≤ 50) heat capacity were used to determine the fractal dimension of Ba_0.5Zr₂(PO₄)₃. Conclusions concerning the topology of the structure of phosphate were drawn. Thermodynamic properties of M_0.5Zr₂(PO₄)₃ (M = Ca, Sr, Ba) were compared.     

Standard enthalpy of formation of (NO2)2[NiF6](cr)

The enthalpies of interactions of (NO₂)₂[NiF₆](cr) with water and aqueous KOH, enthalpies of solution of KF(cr) in dilute aqueous solutions of KNO₃ and KOH, and enthalpy of mixing of solutions of NiF₂, HNO₃, and HF were measured at 298.15 K using isothermic-shell calorimeters. Based on the obtained data and values in the literature, the standard enthalpy of formation of the compound under study was determined by two independent methods: Δ_f H°(NO₂)₂[NiF₆](cr) = −1099 ± 9 kJ/mol.     

苏糖酸钾的低温热溶及标准摩尔生成焓测定

以苏糖酸与碳酸氢钾反应制得苏糖酸钾K(C₄H₇O₅)·H₂O，通过红外光谱、热重、化学分析及元素分析等对其进行了表征。用精密自动绝热热量计测量了该化合物在78K-395K温区的摩尔热容。实验结果表明，该化合物存在明显的脱水转变，其脱水浓度、摩尔脱水焓以及摩尔脱水熵分别为：(380.524 ± 0.093) K，(19.655 ± 0.012) kJ/mol 和 (51.618 ± 0.051) J/（K·mol）。将78K-362K和382K-395K两个温区的实验热容值用最小二乘法拟合，得到了两个表示热容随温度变化的多项式方程。以RBC-II型恒容转动弹热量计测定目标化合物的恒容燃烧能为(-1749.71 ± 0.91) kJ/mol，计算得到其标准摩尔生成焓为(-1292.56 ± 1.06) kJ/mol。     

Synthesis of Some Octahedral Nickel(II) Complexes of One Isomer of Isomeric Me8[14]anes: X-ray Structure of Diisothiocyanato(3,10-C-meso-3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradecane, LC)nickel(II), [NiLC(NCS)2]

One isomer, L_C of the isomeric Me₈[14]anes, L_A, L_B and L_C; on reaction with Ni(NCS)₂ produces a six coordinate octahedral diisothiocyanato complex, [NiL_C(NCS)₂]. This complex undergoes axial substitution reactions with the small ligands to yield corresponding monosubstituted derivatives having general formula [NiL_C(NCS)X] whereas X = Cl, Br, I, NO₂ or NO₃. The complexes have been characterized on the basis of analytical, spectroscopic, magnetic and conductance data. The structure of [NiL_C(NCS)₂] (triclinic, space group P?1, α = 8.0421(17) Å, β = 8.9085(18) Å, χ = 9.687(2) Å, α = 67.561(3) Å, β = 82,896(4) Å, ζ = 598.7(2) Å³, Z = 2, Dc = 1.352 mg/m³, μ(Mo Kα) = 1.003 mm^?1) was confirmed by X-ray crystallography.     

The heat capacity and standard thermodynamic functions of Ni<Subscript>0.5</Subscript>Zr<Subscript>2</Subscript>(PO<Subscript>4</Subscript>)<Subscript>3</Subscript> phosphate over the temperature range from <Emphasis Type="Italic">T</Emphasis> → 0 to 664 K

The temperature dependence of the heat capacity of crystalline nickel zirconium phosphate C°_p = f(T) was measured over the temperature range 6–664 K. The experimental data obtained were used to calculate the standard thermodynamic functions of Ni_0.5Zr₂(PO₄)₃ from T → 0 to 664 K. The standard entropy of phosphate formation from simple substances at 298.15 K was calculated from the absolute entropy of the compound. The data on the low-temperature heat capacity were used to determine the fractal dimension of Ni_0.5Zr₂(PO₄)₃ over the temperature range 30–50 K. Conclusions concerning the heterodynamic characteristics of the structure of Ni_0.5Zr₂(PO₄)₃ were drawn.     

Synthesis,structure and photoluminescence of three 2D Cd(II) coordination polymers based on varied dicarboxylate ligand

Three coordination polymers (CPs) based on different dicarboxylic acids and Cd(II), [Cd₃(tpa)₃(DMA)₄] (1), [Cd₂(thpa)₂(DMA)₂·DMA] (2), and [Cd₃(eba)₃(DMA)] (3) (H₂tpa = terephthalic acid, H₂thpa = thiophenedicarboxylic acid, H₂eba?=?(ethene-1,2-diyl)dibenzoic acid, DMA = N,N′-dimethylacetamide), were synthesized under solvothermal conditions. The CPs were characterized by elemental analysis (EA), single-crystal X-ray crystallography, powder X-ray diffraction, infrared spectroscopy (IR), and thermogravimetric analyses. X-ray crystallographic analysis shows that 1 and 3 exhibit a 2D six-connected hxl network based on hourglass-like [Cd₃(COO)₆] SBUs, whereas 2 displays a 2D 4⁴-sql network based on [Cd₄(COO)₈] SBUs. Thermal stabilities and photoluminescence behaviors of the CPs are also discussed.