Testosterone (17β-hydroxyandrost-4-en-3-one) is the primary naturally occurring anabolic-androgenic steroid. The crystal structures of three short esterified forms of testosterone, including propionate, phenylpropionate, and isocaproate ester, were determined via single-crystal X-ray diffraction. Furthermore, all the samples were investigated using powder X-ray diffraction, and their structural features were described and evaluated in terms of crystal energies and Hirshfeld surfaces. They were also compared with the base form of testosterone (without ester) and the acetate ester. Moreover, from a pharmaceutical perspective, their solubility was evaluated and correlated with the length of the ester.
Keywords: 17β-hydroxyandrost-4-en-3-one; crystal structure; ester; lattice energy; solubility; testosterone.