Molecular Mechanism of Conformational Crossover of Mefenamic Acid Molecules in scCO.

In this work, we studied conformational equilibria of molecules of mefenamic acid in its diluted solution in scCO under isochoric heating conditions in the temperature range of 140-210 °C along the isochore corresponding to the scCO density of 1.1 of its critical value. This phase diagram range totally covers the region of conformational transitions of molecules of mefenamic acid in its saturated solution in scCO.

Correlation between the conformational crossover of carbamazepine and its polymorphic transition in supercritical CO: On the way to polymorph control.

In this paper we have established a correlation between the conformation crossover of carbamazepine and associated polymorph transformation. This was achieved by using a combination of quantum chemical calculations and in situ IR spectroscopy for performing a conformational analysis of carbamazepine molecules in its saturated solution in scCO being in permanent contact with the carbamazepine solid form. Using quantum calculations, we determined two carbamazepine conformers, whose spectral signatures were then found in experimental IR spectra.

Conformational equilibria of pharmaceuticals in supercritical CO, IR spectroscopy and quantum chemical calculations.

In this work we demonstrate a self-consistent effective technique of analyzing the conformational equilibria of active pharmaceutical ingredient (API) molecules dissolved in supercritical carbon dioxide in a wide range of thermodynamic parameters of state. This approach can be useful for pharmaceutics when the crystalline forms of pharmaceuticals with a high purity degree and desirable polymorphism are produced using CO-based supercritical fluids technologies. Within this approach we use a combination of quantum chemical calculations and in situ IR spectroscopy.

Application of Chemometrics Approaches to Analysis of Mid-Infrared Spectra of Ibuprofen Diluted in Supercritical Carbon Dioxide.

This work represents a comprehensive analysis of mid-infrared (mid-IR) spectra of ibuprofen diluted in supercritical CO (in the temperature range of 40-90 ℃ and at the CO density corresponding to 1.3 of its critical value). The study employed mathematical approaches based on data matrix analysis such as two-dimensional cross-correlation analysis (2D-COS) and principal component analysis (PCA).

The interplay between the paracetamol polymorphism and its molecular structures dissolved in supercritical CO2 in contact with the solid phase: In situ vibration spectroscopy and molecular dynamics simulation analysis.

The aim of this paper is to characterize the distribution of paracetamol conformers which are dissolved in a supercritical CO2 phase being in equilibrium with their corresponding crystalline form. The quantum calculations and molecular dynamics simulations were used in order to characterize the structure and analyze the vibration spectra of the paracetamol conformers in vacuum and in a mixture with CO2 at various thermodynamic state parameters (p,T). The metadynamics approach was applied to efficiently sample the various conformers of paracetamol.