Prediction of crystal morphology of 3,4-Dinitro-1H-pyrazole (DNP) in different solvents.

Analytical grade ethyl acetate was used to recrystallize 3,4-Dinitro-1H-pyrazole (DNP), it was found that there were two different morphologies of the crystals. There is a possibility that ethyl acetate undergoes hydrolysis due to the absorption of moisture in the air. The influence of the hydrolysis products of acetic acid and ethanol on the morphology of DNP crystal was considered. In order to investigate the effect of solvents on DNP morphology, there is ongoing research to validate molecular dynamics (MD) simulation results with experiment data. The morphology of DNP in vacuum was predicted by the attachment energy (AE) model, and the growth morphology of DNP in different solvents was simulated by MD method. The modified AE model was successfully verified the phenomenon by the prediction of DNP crystals morphology in Ethyl acetate, H2O, H2O/EtOH and H2O/AcOH. The calculated results show that the two different crystal shapes are diamond and hexagon, respectively. The results are in agreement with the crystal morphology obtained by experiment.