Structural analysis and properties of two novel pharmaceutical salts of letermovir

Two novel pharmaceutical salts of letermovir (LM) were successfully achieved by a slow reaction in so-lution containing LM with ethylenediamine (EDA) and diisopropylamine (DIPA). In this article, crystal structure, X-ray diffraction, thermal properties, 1 H NMR, 13 C NMR, HPLC analysis, stability and solubility of salt 1 and salt 2 have been discussed. Salt 1 crystalized in R 3 space group and salt 2 crystalized in P 3 2 21 space group. The formation of salt was proved by pKa rule and single crystal determination. From the perspective of crystal structure, for salt 1 and salt 2 , the strong hydrogen bond makes the crystal structure more stable. The weak interaction between molecules is further studied by Hirshfeld surface and 2D-fingerprint plots. Notably, this is the first report of a single crystal structure of LM, which could contribute to the development of corresponding drugs. In addition, salt 1 and salt 2 showed better solu-bility and stability under wet conditions, and had the potential to replace the bulk drug. (c) 2023 Elsevier B.V. All rights reserved.