Non-photochemical laser-induced nucleation (NPLIN) is an original and promising nucleation method that has been applied with success to small-molecule organic compounds, proteins, and inorganic compounds, leading to almost 50 publications. After the first application of NPLIN to glycine and carbamazepine, our team has performed NPLIN experiments on sulfathiazole (STZ) for the following reasons: (i) STZ is considered as a model drug for studying polymorphism; (ii) some STZ polymorphs present a two-dimensional packing type, while others have one-dimensional packing; (iii) STZ solubility curves, crystal habits, and crystallization characterization are well documented. First, we have determined the metastable zone limit of STZ in water/ethanol (v/v 1:1) for three temperatures (15, 25, and 40 °C). STZ metastable solutions have been irradiated with a nonfocused nanosecond laser (532 nm) at 25 °C. Nucleation induction time and crystal habits have been compared with those obtained by spontaneous nucleation. Nucleation site is the air/solution interface. We have noted Ind 50 (β) the laser intensity required to induce nucleation with 50% efficiency for a given supersaturation coefficient β. The use of this index has allowed us to compare NPLIN experiments for different compounds in different solutions. A dependency of STZ crystal size and crystal number on the irradiation duration, i.e., pulse number, has been established. Moreover, the obtained crystals have been characterized by Raman spectroscopy and X-ray single crystal diffraction. The role of laser polarization (linear or circular) has been established in comparison with spontaneous nucleation. In order to gain a deeper understanding of this behavior, we have calculated ab initio interaction energies for all dimers existing in the different STZ polymorphs. Theoretical results are coherent with observations.

CHARGE, SPIN AND MOMENTUM DENSITY C425 chemical properties of the nitramine [2]. In the communication will be shown results of structure determination together with a charge density analysis of N-phenyl-Nmethylnitramine together with 1-nitroindoline. Topological properties associated with the bond critical points (BCP), molecular geometry, crystal packing and topological properties of those compounds will also be presented.