Investigation of potential anti-malarial lead candidate 2-(4-fluorobenzylthio)-5-(5-bromothiophen-2-yl)-1,3,4-oxadiazole: Insights from crystal structure, DFT, QTAIM and hybrid QM/MM binding energy analysis

A combined study involving single crystal X-ray diffraction and various theoretical approaches has been used to characterize the 2-(4-fluorobenzylthio)-5-(5-bromothiophen-2-yl)-1,3,4-oxadiazole compound. The crystal structure is primarily stabilized by intermolecular C-H center dot center dot center dot pi, C-H center dot center dot center dot N and C-H center dot center dot center dot F. A short and very rare halogen-halogen contact (Br center dot center dot center dot F) which adopts type I trans geometry along with the S center dot center dot center dot S, N center dot center dot center dot S contacts, which play an important role in the stabilization of the crystal packing. The importance of these contacts is established through various theoretical approaches such as QTAIM and NBO analysis. A detailed CSD analysis of Br center dot center dot center dot F contacts is performed to understand the geometrical preference. A detailed in silico analysis is performed to explore the binding potential of the title compound against the Plasmodium falciparum dihydrofolate reductase (PfDHER). The results clearly suggest that the title compound may be a promising anti-malarial lead candidate by inhibiting the DHFR target and halogenated fragments of the molecule are important for the stabilization of the protein-ligand complex formation. (C) 2018 Elsevier B.V. All rights reserved.