Exceptional thermal stability and thermodynamic properties of lithium based metal–organic framework

Abstract

A three-dimensional lithium-based metalorganic framework Li 2 (2,6-NDC) (2,6-NDC = 2,6-naphthalene dicarboxylate) has been synthesized solvothermally and characterized by X-ray powder diffraction, elemental analysis, FT-IR spectroscopy, thermogravimetry and mass spectrometer analysis (TG-MS). The framework has exceptional stability and is stable to 863 K. The thermal decomposition characteristic of this compound was investigated through the TG-MS from 293 to 1250 K. The molar heat capacity of the compound was measured by temperature modulated differential scanning calorimetry (TMDSC) over the temperature range from 195 to 670 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.

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

“…Through the polynomial representing heat Besides the fundamental and practical importance in compiling various thermodynamic parameters (here C p,m , DH and DS) and their variation with temperature for the two compounds investigated in this study, we have compared the present values with those obtained by our group using the same experimental methods for three other MOFtype materials based on NDC and optionally DMF in their structure, namely Li 2 (2,6-NDC) [24], Li 2 (1,4-NDC)(DMF) [26], and Mg(2,6-NDC)(DMF) 0.66 [31]. While the C p,m , DH and DS values are relatively close for the above studied Ca and Mn compounds, the same parameters for the other three samples give markedly different and random values, confirming that their thermodynamic parameters are rather related to the structure of the compounds than to the nature of their constituents.…”

“…In particular, among compounds prepared in the presence of diethylformamide (DEF) used as solvent and co-ligand, Zn 4 O(2,6-NDC) 3 (DEF) 6 was shown to exhibit a large surface area and thereby an important gas sorption capacity, while Mg 3 (2,6-NDC) 3 (DEF) 4 framework showed a high H 2 adsorption enthalpy and a selective uptake of H 2 and O 2 over N 2 and CO [21][22][23]. Similar (2,6-NDC)-based microporous compounds involving Mg [20] and Li [24] have been reported. The Mg compound, involving a permanent porosity with a large Langmuir surface area and specific pore volume, showed a significant hydrogen storage capacity.…”