Disappearing Conglomerates

International audienc

Disappearing conglomerates, assessment of the threat

International audienc

On the existence of a dynamic critical point by using wet milling on (±) modafinil

This study has been carried out on the molecular compound (±) modafinil, which exhibits five pure polymorphic forms (I, III, IV, V and VI). At P = 1 atm, irrespective of temperature and without any milling energy, Form I is the stable form. Therefore, the other polymorphic forms (III, IV, V and VI) are of monotropic character. The steady states of (±) modafinil have been investigated as a function of wet milling parameters (milling intensity and water concentration). The results presented here suggest the existence of a dynamic critical point defined by Tc ≈ 40°C, Pc ≈ 1 atm, Ic ≈ k R; R=50, Xc = 2% mass percent of water, respectively the critical: mean temperature, global pressure, milling intensity proportional to R and water composition (in mass percent)

In situ X-ray for monitoring crystallization in solution : In-situX®

International audienc

Relevance of Second Harmonic Generation Microscopy (SHG-M) in Material Sciences

International audienc

Practical Role of Racemization Rates in Deracemization Kinetics and Process Productivities

International audienc

Prenucleation self-assembly and chiral discrimination mechanisms during solution crystallisation of racemic diprophylline

The crystallisation behaviour of (RS)-diprophylline (DPL) in two different solvents is investigated to assess the incidence of solvated pre-associations on nucleation, crystal growth and chiral discrimination. In the solvated state, Raman spectroscopy shows that dimeric associations similar to those depicted in the crystalline solid solution (ssRII) predominate in isopropanol (IPA), which may account for the systematic spontaneous nucleation of this crystal form from this solvent. By contrast, spontaneous nucleation in DMF yields the stable racemic compound RI, consistently with the distinct features of the Raman spectrum collected in this solvent. A crystal growth study of ssRII in IPA reveals that the crystal habitus is impacted by the solution enantiomeric excess; this is explained by increased competition between homo- and heterochiral pre-associations. This is supported by a molecular modelling study on the enantiomeric selectivity of the DPL crystal lattices. The combination of assessment methods on solution chemistry, nucleation and chiral discrimination provides methodological tools from which the occurrence of solid solutions can be rationalised

Chirality and supramolecular chirality, chiral discrimination in the solid-state and break of symmetry

International audienc

Preferential Crystallization

International audienc

Chiral Discrimination in the Solid State: Applications to Resolution and Deracemization

International audienc