Heat capacity and thermodynamical properties of the crystal of [RE2(Glu)2(H2O)8](ClO4)4·H2O (RE = Nd, Eu, Dy)

Abstract

Thermodynamical data of rare earth complexes with amino acid are important for engineering chemistry and fundamental chemistry. However, they have rarely been reported. In this work, a series of crystalline complexes of rare earth perchlorate coordinated with glutamic acid have been synthesized in water medium, and their thermodynamical data, including the heat capacity in low temperature range and the standard enthalpy of formation, were determined. These complexes were identified to be [RE 2 (Glu) 2 (H 2 O) 8 ](ClO 4 ) 4 ·H 2 O (RE = Nd, Eu, Dy) by using thermogravimetric analysis (TG), differential thermal analysis (DTA), and chemical and elementary analyses. Their purity has been determined. No melting points were observed for all the three complexes. The heat capacity of the complexes was measured by an adiabatic calorimeter from 79 to 370 K. Abnormal heat capacity values were detected for two of the complexes and the decomposition range of one complex was found. The temperature, enthalpy change and entropy change of the decomposition processes of the three complexes were calculated. The polynomial equations of heat capacity in the experimental temperature range have been obtained by least squares fitting. The standard enthalpy of formation was determined by an isoperibol reaction calorimeter at 298.15 K.complex of rare earth, [RE 2 (Glu) 2 (H 2 O) 8 ](ClO 4 ) 4 ·H 2 O (RE = Nd, Eu, Dy; Glu = glutamic acid), low-temperature heat capacity, standard enthalpy of formation

Standard Enthalpies of Formation of Rare Earthl-Proline Chloride Complexes [RE(l-Pro)2(H2O)5]Cl3(RE = Ho, Er)

“…A WZS-1 Abbe refractometer and UV-16 ultraviolet−visible spectrophotometer were used to study the refractive index and ultraviolet spectrum of the reactant [RE(NO 3 ) 3 ·6H 2 O + 2 l -Pro + 3NaCl] and the product {[RE( l -Pro) 2 (H 2 O) 5 ]Cl 3 + 3NaNO 3 + H 2 O} in 2.4 cm 3 of 2 mol·dm −3 HCl solution, the results show that the reactant and product have the same refractive index and ultraviolet spectrum. So we concluded that the tested states have the same final thermochemistry state in the experiments, which means the design of the thermochemical cycle is reasonable …”

“…So we concluded that the tested states have the same final thermochemistry state in the experiments, which means the design of the thermochemical cycle is reasonable. 16…”

Thermodynamical Study on Rare Earth L-Isoleucine Chlorate Complexes [RE₂(lle)₄(H₂O)₈](ClO₄)₆ (RE = Nd, Er)

“…1) was designed according to Hess law. [5] Δ r O were weighed and mixed in the bottom of the sample cell. A tube loaded with 1.8 mL of 2 mol•L -1 HCl solution was placed above the mixed complexes.…”

“…The dissolution enthalpies of the reactants (RECl3•6H 2 O+Ile+NaClO 4 •H 2 O, n RECl3•6H2O : n Ile : n NaClO4•H2O = 1 : 2 : 3) and products {[RE 2 (Ile) 4 (H 2 O) 8 ](ClO 4 ) 6 +NaCl, n [RE2(Ile)4(H2O)8](ClO4)6 :n NaCl = 1 : 6} in 1.8 ml 2 mol•L -1 HCl solution. H represents the dilution enthalpy of the process of adding 0.0047 g water into 1.8 mL of 2 mol•L -1 HCl solution, and the value of Δ d H was so small that can be neglected [5]. …”