A gravimetric method is adopted to measure the solid–liquid
equilibrium of N
1,N
3,N
5-tris(pyridin-4-yl)benzene-1,3,5-tricarboxamide
(TPBTC), a hydrogen-bonded organic framework (HOF) monomer in different
solvents (methanol, dichloromethane, isopropanol, n-hexane, acetone, ethanol, 2-butanone, n-butanol,
acetonitrile, water, ethyl acetate, and n-propanol).
The experiment is carried out at atmospheric pressure, and the experimental
temperatures range from 283.15 to 323.15 K. The powder X-ray diffraction
analysis was performed on the equilibrium solid-phase characterization
of TPBTC in different solvents, and the solid form of solute in equilibrium
with different solvents was a mixture of three kinds of crystalline
forms and an amorphous form. In the 12 monosolvents, the solubility
increased with absolute temperature, and the following order was obtained:
2-butanone > isopropanol > n-propanol > n-butanol > ethyl acetate > acetonitrile > methanol
> ethanol > dichloromethane
> n-hexane > acetone > water. In the studied
temperature
range, the maximum and minimum values were recorded for 2-butanone
(0.6753 × 10–3 mol/mol at 323.15 K) and water
(0.004650 × 10–3 mol/mol at 283.15 K), respectively.
The solubility behavior and solvent effects in various solvents were
first investigated by the hydrogen bond acceptor tendencies as the
main factor then interpreted by solvent polarity, cohesive energy
density, and steric effect for some exceptions. In addition, the solid–liquid
equilibrium data of TPBTC were correlated with the Yaws model and
the Apelblat model. Furthermore, the two thermodynamic models were
evaluated using the Akaike Information Criterion and Akaike weights.
It can be observed that the Yaws model was more appropriate than the
Apelblat model.