Synthesis, characterization, biological and DFT studies of charge-transfer complexes of antihyperlipidemic drug atorvastatin calcium with Iodine, Chloranil, and DDQ

Extremely coloured charge-transfer complexes (CTCs) of antihyperlipidemic drug, atorvastatin calcium (ATC) acting as n-electron donor with the electron acceptors, namely, iodine as sigma-acceptor, 2,3,4,6-tetra chloro-1,4-benzoquinone (chloranil, CHL), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as pi-acceptors have been explored. Elemental analysis, thermal analysis, FTIR spectroscopy, Raman spectroscopy, NMR spectroscopy, and mass spectroscopy techniques were used to explain the chemical mechanism of the synthesized ATC-CTCs. It has been found that the stoichiometry of the complexes was to be 1:1 ratio in ATC-iodine and 1:2 ratio in ATC-CHL; ATC-DDQ. Elemental and mass analysis were confirmed the above ratio of ATC-CTCs which was [(ATC)I]I-3, [(ATC)(CHL)(2)], and [(ATC)(DDQ)(2)] respectively. The biological activities of the formed ATC-CTCs were also tested against various bacterial strains. In addition, the frontier molecular orbitals (FMO) of the title compound was performed at the HF/6-311G** level to display the favourable reactivity tendency and the best suitable site for the electrophilic and nucleophilic attacks. The natural bond orbital (NBO) analysis was employed to predict the possible non-covalent inter- actions and its result disclosed that the n -> Pi* and Pi -> Pi* interactions had a critical role in the enlight-ening of the stabilization of the compound. The achieved results are more appropriate for the estimation of antihyperlipidemic drug, ATC in pharmaceutical dosage forms. (C) 2021 Elsevier B.V. All rights reserved.