The dissolution enthalpies of glycine in aqueous solutions of acetamide, N-methylacetamide, N,N-dimethylacetamide, N-ethylformamide,
N,N-diethylformamide and N,N-diethylacetamide were measured at 298.15 K. The enthalpic pair interaction coefficients of glycine
zwitterion-amide molecules were determined by using standard solution enthalpies of glycine in water and aqueous solutions
of amides. The additivity of groups concept of Savage and Wood was used to estimate the contribution of each of the functional
groups of the studied amides.
Authors:V. Drebushchak, Yu. Kovalevskaya, I. Paukov, and E. Boldyreva
Low-temperature heat capacity of two polymorphs of glycine (α and γ) was measured from 5.5 to 304 K and thermodynamic functions
were calculated. Difference in heat capacity between polymorphs ranges from +26% at 10 K to -3% at 300 K. The difference indicates
the contribution into the heat capacity of piezoelectric γ polymorph, probably connected with phase transition and ferroelectricity.
Thermodynamic evaluations show that at ambient conditions γ polymorph is stable and α polymorph is metastable.
Authors:Carmen Paraschiv, B. Jurca, Adelina Ianculescu, and Oana Carp
Two bismuth ferrite potential precursors systems, namely Fe(NO3)3·9H2O-Bi(NO3)3·9H2O-glycine/urea with different metal nitrate/organic compound molar ratios have been investigated in order to evaluate their
suitability as BiFeO3 precursors. The presence into the precursor of both reducing (glycine and urea) and oxidizing (NO3−) components, modifies dramatically their thermal behaviour comparative with the raw materials, both from the decomposition
stoichiometries and temperature occurrence intervals points of view. Also, the thermal behaviour is dependent on the fuel
nature but practically independent with the fuel content. The fuel nature influences also some characteristics of the resulted
oxides (phase composition, morphologies). In the case of the oxides prepared using urea as fuel, a faster evolution toward
a single phase composition with the temperature rise is evidenced, the formation of the BiFeO3 perovskite phase being completed in the temperature range of 500–550°C.
Authors:C. Wen-Sheng, L. Yi, Z. Chuan-Pei, L. Qiang-Guo, and Q. Song-Sheng
The solid-state coordination reactions of lanthanum chloride with alanine and glycine, and lanthanum nitrate with alanine
have been studied by classical solution calorimetry. The molar dissolution enthalpies of the reactants and the products in
2 mol L-1 HCl solvent of these three solid-solid coordination reactions have been measured using an isoperibol calorimeter. From the
results and other auxiliary quantities, the standard molar formation enthalpies have been determined to be ΔfHmθ[La(Ala)3Cl33H2O(s), 298.2 K]= -3716.3 kJ mol-1, ΔfHmθ [La(Gly)3Cl35H2O(s), 298.2 K]= -4223.0 kJ mol-1 and ΔfHmθ [La(Ala)4(NO3)3H2O(s), 298.2 K]= -3867.57 kJ mol-1, respectively.
Authors:Tongshan Sun, Yuting Zhao, Jaihui Jin, and Daqing Wang
Four complexes of rare earth bromides with amino acids, REBr3·3L·3H2O (RE=La, Nd;L=glycine or alanine) were prepared and characterized by means of chemical analysis, elemental analysis, molar conductivity,
thermogravimetry, IR spectra and X-ray diffraction. Their thermal decomposition kinetics from ambient temperature to 500°C
were studied by means of TG-DTG techniques under non-isothermal conditions. The kinetic parameters (activation energyE and pre-exponential constantA) and the most probable mechanisms of thermal decomposition were obtained by using combined differential and integral methods.
The thermal decomposition processes of these complexes are distinguished as being of two different types, depending mainly
on the nature of the amino acid.
Authors:W. Xinmin, Q. Chuansong, Q. Songsheng, and T. Zhicheng
Rare-earth perchlorate complex coordinated with glycine [Nd2(Gly)6(H2O)4](ClO4)6�5H2O was synthesized and its structure was characterized by using thermogravimetric analysis (TG), differential thermal analysis
(DTA), chemical analysis and elementary analysis. Its purity was 99.90%. Heat capacity measurement was carried out with a
high-precision fully-automatic adiabatic calorimeter over the temperature range from 78 to 369 K. A solid-solid phase transformation
peak was observed at 256.97 K, with the enthalpy and entropy of the phase transformation process are 4.438 kJ mol−1 and 17.270 J K−1 mol−1, respectively. There is a big dehydrated peak appears at 330 K, its decomposition temperature, decomposition enthalpy and
entropy are 320.606 K, 41.364 kJ mol−1 and 129.018 J K−1 mol−1, respectively. The polynomial equations of heat capacity of this compound in different temperature ranges have been fitted.
The standard enthalpy of formation was determined to be −8023.002 kJ mol−1 with isoperibol reaction calorimeter at 298.15 K.
Authors:Zh. F. Gesse, G. I. Repkin, V. A. Isaeva, and V. A. Sharnin
Sufficient amount of information about enthalpy changes of reactions in water was accumulated for complex formation between transition metals ions and amino acids anions and glycine-ion [ 1 – 3 ] and for complex formation of glycine and