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The enthalpies of dilution of matrine (MAT) in pure water and aqueous sodium chloride solutions were determined by isothermal titration microcalorimetry at 298.15 K, and the corresponding homogeneous enthalpic interaction coefficients were calculated according to the modified McMillan–Mayer model. The values of enthalpic pair-wise interaction coefficients, h 2, are all positive and become more positive with increasing concentration of sodium chloride.

The low-temperature heat capacities of berberine hydrochloride were measured over the temperature range from 78 to 350 K by an adiabatic calorimeter. The thermodynamic functions H T − H 298.15 and S T − S 298.15 were derived from the heat capacity data. The results showed that the structure of berberine hydrochloride was stable over the temperature range from 78 to 350 K. The thermal stability of the compound was further tested by DSC and TG measurements. The results were in agreement with those obtained from adiabatic calorimetry experiment. The standard molar enthalpy of formation in the crystalline state of berberine hydrochloride was obtained from the standard molar energies of combustion in oxygen at T = 298.15 K, measured by a rotating-bomb combustion calorimeter.

The dilution enthalpies of D-mannitol and D-sorbitol in aqueous sodium chloride solution at various concentrations have been determined by isothermal microcalorimetry at 298.15 K. The homogeneous enthalpic interaction coefficients over a quite large range of concentration of aqueous sodium chloride solutions have been calculated according to the excess enthalpy concept. The results show that enthalpic pairwise interaction coefficients (h 2) of D-mannitol and D-sorbitol are positive in aqueous sodium chloride solution and become more positive with increase of the concentration of sodium chloride. The results are interpreted in terms of the different conformations of the two polyols, solute-solute and solute-solvent interactions involved by solvent effects.

Low-temperature heat capacities of a solid complex Zn(Val)SO4·H2O(s) were measured by a precision automated adiabatic calorimeter over the temperature range between 78 and 373 K. The initial dehydration temperature of the coordination compound was determined to be, TD=327.05 K, by analysis of the heat-capacity curve. The experimental values of molar heat capacities were fitted to a polynomial equation of heat capacities (Cp,m) with the reduced temperatures (x), [x=f (T)], by least square method. The polynomial fitted values of the molar heat capacities and fundamental thermodynamic functions of the complex relative to the standard reference temperature 298.15 K were given with the interval of 5 K. Enthalpies of dissolution of the [ZnSO4·7H2O(s)+Val(s)] (Δsol Hm,l0) and the Zn(Val)SO4·H2O(s) (Δsol Hm,20) in 100.00 mL of 2 mol dm−3 HCl(aq) at T=298.15 K were determined to be, Δsol Hm,l0=(94.588±0.025) kJ mol−1 and Δsol Hm,20=–(46.118±0.055) kJ mol−1, by means of a homemade isoperibol solution–react...

The two solid-state coordination reactions (1) CuAc 2 · H 2 O ( s )+2 Ala ( s )→trans- Cu ( Ala ) 2 ( s )+2 HAc ( l )+ H 2 O ( l ) (2) CuAc 2 · H 2 O ( s )+2 Gly ( s )→trans- Cu ( Gly ) 2 · H 2 O ( s )+2 HAc ( l ) have been studied by solution calorimetry. The molar dissolution enthalpies of the reactants and the products in some solvents (such as 2 mol l−1 HCl or its solutions) of these solid–solid coordination reactions have been measured by an isoperibol solution calorimeter. The standard molar formation enthalpies of [trans-Cu(Ala)2(s), 298.15 K] and [trans-Cu(Gly)2(s), 298.15 K] have been determined to be −1015.42 ± 0.06 and 1252.36 ± 0.05 kJ mol−1, respectively, from the results of the molar dissolution enthalpies and other auxiliary thermodynamic data.

The solid-state coordination reactions: 2 HQ ( s )+ Co ( Ac ) 2 ·4 H 2 O ( s )→ Co ( HQ ) 2 ·2 H 2 O ( s )+2 HAc ( l )+2 H 2 O ( l ) 2 HQ ( s )+ Zn ( Ac ) 2 ·2 H 2 O ( s )→ Zn ( HQ ) 2 · H 2 O ( s )+2 HAc ( l )+ H 2 O ( l ) have been studied by solution calorimetry. The molar dissolution enthalpies of the reactants and the products in a certain solvent, 4 mol l −1 HCl, of this solid–solid coordination reaction have been measured using an isoperibol calorimeter. From the results and other auxiliary quantities, the standard molar formation enthalpies of [Co(HQ) 2 ·2H 2 O(s), 298.15 K], [Zn(HQ) 2 ·H 2 O(s), 298.15 K] and have been determined to be Δ f H m Θ (Co(HQ) 2 ·2H 2 O(s), 298.15 K)=−766.9±3.0 kJ mol −1 , Δ f H m Θ (Zn(HQ) 2 ·H 2 O(s), 298.15 K)=−580.7±3.0 kJ mol −1 .