Formation and stabilization mechanism of mesoscale clusters in solution

Polymorphism of Pradofloxacin: Crystal Structure Analysis, Stability Study, and Phase Transformation Behavior

PURPOSE

Pradofloxacin is an important antibiotic with poor physical stability. At present, there is no systematic study on its polymorphic form. The purpose of this study is to develop new crystal forms to improve the stability of Pradofloxacin and systematically study the crystal transformation relationships to guide industrial production.

METHOD

In this work, three solvent-free forms (Form A, Form B and Form C), a new dimethyl sulfoxide solvate (Form PL-DMSO) and a new hydrate (Form PL-H) were successfully obtained and the single crystal data of Form A, Form B and Form PL-DMSO were solved for the first time. Various solid state analysis techniques and slurry experiments have been used to evaluate the stability and determine phase transformation relationships of five crystal forms, the analysis of crystal structure provided theoretical support for the results.

RESULT

The water vapor adsorption and desorption experiences of Forms A, B, C and Form PL-H were studied, and the results show that the new hydrate has good hygroscopic stability and certain development potential. The thermal stability of different forms was determined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) and the crystal structure shows that there are more hydrogen bonds and C - H···π interactions in form B, which is the reason why Form B is more stable than form A. Finally, the phase transformation relationships of the five crystal forms were systematically studied and discussed.

CONCLUSION

These results are helpful to provide guiding methods in the production and storage of pradofloxacin.

Perspective: New directions in dynamical density functional theory

Classical dynamical density functional theory (DDFT) has become one of the central modeling approaches in nonequilibrium soft matter physics. Recent years have seen the emergence of novel and interesting fields of application for DDFT. In particular, there has been a remarkable growth in the amount of work related to chemistry. Moreover, DDFT has stimulated research on other theories such as phase field crystal models and power functional theory. In this perspective, we summarize the latest developments in the field of DDFT and discuss a variety of possible directions for future research.