You-Ying Di

Crystal structures, lattice potential energies, and thermochemical properties of crystalline compounds (1-C(n)H(2n+1)NH3)2ZnCl4(s) (n = 8, 10, 12, and 13).

As part of our ongoing project involving the study of (1-C(n)H(2n+1)NH(3))(2)MCl(4)(s) (where M is a divalent metal ion and n = 8-18), we have synthesized the compounds (1-C(n)H(2n+1)NH(3))(2)ZnCl(4)(s) (n = 8, 10, 12, and 13), and the details of the structures are reported herein. All of the compounds were crystallized in the monoclinic form with the space group P2(1)/n for (1-C(8)H(17)NH(3))(2)ZnCl(4)(s), P21/c for (1-C(10)H(21)NH(3))(2)ZnCl(4)(s), P2(1)/c for (1-C(12)H(25)NH(3))(2)ZnCl(4)(s), and P2(1)/m for (1-C(13)H(27)NH(3))(2)ZnCl(4)(s). The lattice potential energies and ionic volumes of the cations and the common anion of the title compounds were obtained from crystallographic data. Molar enthalpies of dissolution of the four compounds at various molalities were measured at 298.15 K in the double-distilled water. According to Pitzers theory, molar enthalpies of dissolution of the title compounds at infinite dilution were obtained. Finally, using the values of molar enthalpies of dissolution at infinite dilution (Δ(s)H(m)(∞)) and other auxiliary thermodynamic data, the enthalpy change of the dissociation of [ZnCl(4)](2-)(g) for the reaction [ZnCl(4)](2-)(g)→ Zn(2+)(g) + 4Cl(-)(g) was obtained, and then the hydration enthalpies of cations were calculated by designing a thermochemical cycle.

Crystal structure and thermodynamic properties of phase change material bis(1-dodecylammonium) tetrachlorochromate (C12H25NH3)2CdCl4(s)

A novel complex bis(1-dodecylammonium) tetrachlorochromate (C12H25NH3)2CdCl4(s) (abbreviated as C12Cd(s)) was synthesized by liquid phase reaction. Crystal structure and composition of the complex were determined by X-ray crystallography, chemical analysis, and elemental analysis. It is triclinic, the space group is P−1 and Z = 2. Lattice potential energy (LPE) of the complex was calculated to be kJ·mol−1 from crystallographic data. Low-temperature heat capacities were measured by a precise automatic adiabatic calorimeter over the temperature range from 78 to 370 K. The temperature, molar enthalpy, and entropy of the phase transition of the complex were determined to be 331.88 ± 0.02 K, 55.79 ± 0.46 kJ·mol−1, and 168.10 ± 1.38 J·K−1·mol−1, respectively. Two polynomial equations of the heat capacities as a function of temperature were fitted by least-square method. Smoothed heat capacities and thermodynamic functions of the complex were calculated.

Investigation on phase transitions of 1-decylammonium hydrochloride as the potential thermal energy storage material

1-Decylammonium hydrochloride was synthesized by the method of liquid phase synthesis. Chemical analysis, elemental analysis, and X-ray single crystal diffraction techniques were applied to characterize its composition and structure. Low-temperature heat capacities of the compounds were measured with a precision automated adiabatic calorimeter over the temperature range from 78 to 380 K. Three solid–solid phase transitions have been observed at the peak temperatures of 307.52 ± 0.13, 325.02 ± 0.19, and 327.26 ± 0.07 K. The molar enthalpies and entropies of three phase transitions were determined based on the analysis of heat capacity curves. Experimental molar heat capacities were fitted to two polynomial equations of the heat capacities as a function of temperature by least square method. Smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at intervals of 5 K based on the fitted polynomials.

n-Dodecyl­ammonium bromide monohydrate

In the title compound, C12H28N+·Br−·H2O, the ionic pairs formed by n-dodecylammonium cations and bromide anions are arranged into thick layers; these layers are linked in a nearly perpendicular fashion [the angle between the layers is 85.84 (5)°] by hydrogen-bonding interactions involving the water molecules. The methylene part of the alkyl chain in the cation adopts an all-trans conformation. In the crystal structure, molecules are linked by intermolecular N—H⋯Br, O—H⋯Br and N—H⋯O hydrogen bonds.

Synthesis, Crystal Structure and Low-temperature Heat Capacities of Bis(n-undecylammonium)tetrachlorocadmiumate

The crystalline bis(n-undecylammonium)tetrachlorocadmiumate (C11H23NH3)2CdCl4(s) (abbre- viated as C11Cd(s)) was synthesized. The crystal structure and composition of the complex were determined by single crystal X-ray diffraction, chemical analysis and elementary analysis. The lattice potential energy was calculated to be UPOT=908.18 kJmol -1 from crystallographic data. Low-temperature heat capacities of the complex were measured by a precision automatic adiabatic calorimeter over the temperature range from 78 to 395 K. The experimental results show that there are two continuous phase changes appearing in the temperature region. The peak temperatures, molar enthalpies and entropies of two phase transitions for the complex were determined to be: Ttrs,1=(321.88±0.07) K, ΔtrsHm,1=(37.59±0.17) kJmol -1 and ΔtrsSm,1=

Low-temperature heat capacities and thermodynamic properties of n-undecylammonium bromide monohydrate C11H28BrNO(s)

Crystal structure of n-undecylammonium bromide monohydrate was determined by X-ray crystallography. Low-temperature heat capacities of the compound were measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 390 K. Two solid–solid phase transitions were observed for the title compound. The temperatures, molar enthalpies, and entropies of the phase transitions were derived based on the analysis of heat–capacity curve. Two polynomial equations of heat capacities as a function of temperature were fitted by least-squares method. Based on the two polynomial equations, smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at 5 K intervals.

Crystal Structure and Solid–Solid Phase Transition of 1-Dodecylamine Hydrobromide

Abstract 1-dodecylamine hydrobromide was synthesized. The crystal structure of the compound was determined by X-ray crystallography. Low-temperature heat capacities of the title compound were measured by an adiabatic calorimeter over the temperature range from 78 to 390 K. Three solid–solid phase transitions were observed at the peak temperatures of (329.278±0.234), (337.805±0.326), and (347.371±0.154) K. The molar enthalpies and entropies of the three phase transitions of the substance were calculated based on the analysis of heat capacity curves. Experimental values of heat capacities for the title compound were fitted to two polynomial equations. Three solid–solid phase transitions and a melting process of 1-dodecylamine hydrobromide were verified by DSC technique. In addition, the reversibility and repeatability of the three phase transitions were discussed.

Thermochemistry on the Solid State Coordination Compounds M(Nic)2 · H2O(s) (M = Mn and Mg, Nic = Nicotinate)

Abstract Two novel solid state coordination compounds – manganese nicotinate monohydrate and magnesium nicotinate monohydrate were synthesized by the method of room temperature solid phase synthesis and ball grinder. FTIR, chemical and elemental analyses and X-ray powder diffraction techniques were applied to characterize the structure and composition of these complexes. In accordance with Hess’ law, hermochemical cycles were designed, the enthalpy changes of the solid phase reactions of nicotinic acid with manganese acetate tetrahydrate and magnesium acetate tetrahydrate were determined as ΔrH0m,l = (39.66±0.36) kJ · mol–1 and ΔrH0m,2 = (40.73±0.17) kJ · mol–1 by use of an isoperibol solution-reaction calorimeter, respectively. The standard molar enthalpy of formation of the title complexes M(Nic)2 · H2O(s) were calculated as ΔfH0Mn(Nic)2·H2O = –(1165.01±2.01) kJ · mol–1 and ΔfH0Mg(Nic)2·H2O = –(1390.49±1.99) kJ · mol–1 by use of the enthalpies of dissolution and other auxiliary thermodynamic data. In addition, the values of the standard molar enthalpies of formation of M(Nic)2·H2O(s) (M = Mg, Mn, Zn) were compared, a law of change of [–ΔfH0Zn(Nic)2·H2O] < [–ΔfH0Mn(Nic)2·H2O] < [–ΔfH0Mg(Nic)2·H2O] can be obtained, and was in relation with the stability of the three monohydrated nicotinates.

n-Tridecyl-amine chloride monohydrate.

In the title compound, C13H30N+·Cl−·H2O, the C13H27 alkyl chain is in an all-trans conformation. In the crystal, intermolecular N—H⋯Cl, N—H⋯O and O—H⋯Cl hydrogen bonds connect the components into layers parallel to (010), with the alkyl chains oriented approximately perpendicular to these layers.

Penta­decyl­ammonium methyl sulfate

In the crystal of the title compound, C15H34N+·CH3SO4 −, the cations and anions are joined together via strong N—H⋯O hydrogen bonds into layers parallel to (001).