The past three decades have witnessed the rapid development of fast scanning calorimetry (FSC), a novel calorimetric technique that employs micromachined sensors. The key advances of this technique are the ultrahigh scanning rate, which can be as high as 106 K s–1, and the ultrahigh sensitivity, with a heat capacity resolution typically better than 1 nJ K–1. Nanocalorimetry has attracted much attention in materials science, where it is applied to perform quantitative analysis of rapid phase transitions, particularly on fast cooling. Another emerging area of application of FSC is physical chemistry, with a focus on the thermophysical properties of thermally labile compounds. Quantities like fusion temperature, fusion enthalpy, sublimation, and vaporization pressures and enthalpies of such molecules became available. This paper shortly reviews the development of FSC and summarizes its applications to various materials ranging from polymers (including proteins) to pharmaceuticals. Several of them are based on results from the laboratory of fast scanning calorimetry at Kazan Federal University, where applications of FSC, especially for biopolymers and low-molecular-mass organic compounds, were developed. Furthermore, FSC, coupled with structural characterization techniques, such as polarized optical (POM) and atomic force (AFM) microscopy, as well as infrared spectroscopy (IR), is presented. Finally, current challenges and future outlooks are discussed. Given the unique attributes of the technique, nanocalorimetry is expected to attract increasing attention, especially concerning the characterization of fast phase transitions and evaluation of thermally labile compounds.
This work aims to assess the intermolecular interaction of choline ionic liquids (ILs) (choline malonate ([Ch][Mal]), choline succinate ([Ch][Suc]), and choline valinate ([Ch][Val]) with two enzymes (lysozyme and α-chymotrypsin). We evaluated the state of the tertiary protein structure using circular dichroism (CD) spectrometry and quantified the binding parameters of the binding of the ionic liquids to the enzymes by fluorescence spectroscopy. The binding energies of the enzymes and the localization of ions on them were estimated using the molecular docking. We then analyzed the relationship between the enzymes’ thermostability and their tendency towards aggregation in the enzyme/ionic liquid systems. The obtained results were compared with previous data on albumins to identify similarities and differences between the behavior of enzymes and albumins in ionic liquid solutions. Despite the comparable values of the binding constants, the effect of ionic liquids on the thermostability of enzymes was the opposite of their effect on albumins. In addition, although these ionic liquids promoted aggregation in both enzymes and albumins, this effect was much more pronounced for albumins.
In this work, an approach to the calculation of hydrogen bonding enthalpies is proposed. It employs the correlation proposed by M.H. Abraham, establishing the connection between the equilibrium constant (KHB) and acidity () and basicity () parameters: log KHB = 7.354 · · − 1.099. Hydrogen bonding enthalpy (ΔHBH) is found using the compensation relationship with Gibbs energy (ΔHBG): ΔHBG = 0.66 · ΔHBH + 2.5 kJ·mol−1. This relationship enables the calculation of the enthalpy, Gibbs energy and entropy of hydrogen bonding. The validity of this approach was tested against 122 experimental hydrogen bonding enthalpies values available from the literature. The root mean square deviation and average deviation equaled 1.6 kJ·mol−1 and 0.5 kJ·mol−1, respectively.
In the present work, the thermochemistry of solution, solvation, and hydrogen bonding of cyclic amides in proton acceptor (B) and proton donor (RXH) solvents were studied. The infinite dilution solution enthalpies of δ-valerolactam, N-methylvalerolactam, ε-caprolactam, and N-methylcaprolactam were measured at 298.15 K. The solvation enthalpies of cyclic amides were calculated based on the measured solution enthalpies and sublimation/vaporization enthalpies from literature. The enthalpies of hydrogen bonding between cyclic amides and proton acceptor and donor solvents were then calculated as a difference between the total solvation enthalpy and the non-specific contribution. The latter was estimated via two different approaches in proton donor and proton accepting solvents. The effect of the cycle size on the strength of hydrogen bonding of the cyclic amides in solution is discussed.
1,3,5-Tris-(α-naphthyl)benzene is an organic non-electrolyte with notable stability of an amorphous phase. Its glassy and supercooled liquid states were previously studied by spectroscopic and calorimetric methods. Despite the continuing interest in its amorphous state and, particularly, vapor-deposited glasses, the thermodynamic parameters of the vaporization of 1,3,5-tris-(α-naphthyl)benzene have not been obtained yet. Likewise, the reliable evaluation of the thermodynamic parameters of fusion below the melting point, required to establish the thermodynamic state of its glass, is still an unsolved problem. In this work, the heat capacities of crystalline and liquid phases, the temperature dependence of the saturated vapor pressures, fusion and vaporization enthalpies were determined using differential and fast scanning calorimetry and were verified using the estimates based on solution calorimetry. The structural features of 1,3,5-tris-(α-naphthyl)benzene are discussed based on the computations performed and the data on the molecular refractivity. The consistency between the values obtained by independent techniques was demonstrated.