Intermolecular charge-transfer complexes between chlorothiazide antihypertensive drug against iodine sigma and picric acid pi acceptors: DFT and molecular docking interaction study with Covid-19 protease

The interaction of chlorothiazide (CH) as donor (D) with picric acid (PA) and iodine (I2) as π- and σ-acceptors (A), respectively, gives charge-transfer (CT) complexes as a final products. The reaction of donor and acceptors were studied spectrophotometrically. The complexes are generally of the n-π* and n-σ* types, with the ground state wave function primarily characterized by the non-bonding structure. For the micro determination of chlorothiazide using picric acid and iodine as acceptors, the ideal conditions encouraging the formation of complexes are thoroughly explored. It was discovered that the stoichiometry of the molecular structure is 1:1 (D:A). The equilibrium constant and the molar extinction coefficient were calculated using Benesi-Hildebrand and its modifications. DFT/TD-DFT calculations with B3LYP/LanL2DZ and 6-311G++ level of theory were used to provide comparable theoretical data along with electronic energy gap of HOMO→LUMO. Molecular docking calculations have been performed between CT complexes and Covid-19 protease (6LU7) to study the interaction between them and their inhibitory effect.

The derivation and characterization of quinine charge-transfer complexes with inorganic and organic acceptors in liquid and solid form

Quinine (QN), chloroquine (CQ), and hydroxychloroquine (HCQ) belong to the 4-aminoquinoline family. QN was used to treat the Spanish Flu, while CQ and HCQ are under consideration for the treatment of COVID-19. This work aimed to investigate the charge-transfer (CT) interaction between QN compound with five acceptor molecules: iodine crystals (A1), 7,7,8,8-tetracyanoquinodimethane (A2), 2,3-dichloro-5,6-dicyano-p-benzoquinone (A3), chloranilic acid (A4), and tetrafluoro-1,4-benzoquinone (A5). The experimental results indicated that QN formed stable and vividly colored CT complexes with these acceptors. Strong color changes occurred upon complexation in both liquid and solid forms. The analytical findings suggest that QN reacted with the A2, A3, A4 and A5 acceptors at a 1:1 molar ratio and a 1:2 ratio with A1 acceptor. The charge migration occurred from QN to A1 via the formation of a tri-iodide complex, while the charge migration occurred from QN to A2, A3, A4, and A5 acceptors through an n → π* interaction.

New Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Zn(II), Cd(II), and Hg(II) Gibberellate Complexes: Synthesis, Structure, and Inhibitory Activity Against COVID-19 Protease.

Transition metals such as Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Zn(II), Cd(II), and Hg(II) have been reacted with gibberellic acid (HGA) to give novel complexes, and those have been characterized by physical, spectral and analytical methods. The plant hormone gibberellate acts as a deprotonated bidentate ligand in the complexation reaction with central metal ions in the ratio 1 : 2 (M n+ : GA). The complexes [M(GA)2(H2O)2], where [M = Mn(II), Co(II), and Ni(II)] form octahedral structures, while [M(GA)2] complexes [M = Zn(II), Cd(II), and Hg(II)] display four-coordination geometry. The octahedral structures of Cr(III) and Fe(III) complexes are characterized by the general formula [M(GA)2(H2O)(Cl)]. Computational study carried out has determined possible interactions of the complexes with COVID-19 (6LU7).