Charge-transfer chemistry of azithromycin, the antibiotic used worldwide to treat the coronavirus disease (COVID-19). Part III: A green protocol for facile synthesis of complexes with TCNQ, DDQ, and TFQ acceptors

Investigating the chemical properties of molecules used to combat the COVID-19 pandemic is of vital and pressing importance. In continuation of works aimed to explore the charge-transfer chemistry of azithromycin, the antibiotic used worldwide to treat COVID-19, the disease resulting from infection with the novel SARS-CoV-2 virus, in this work, a highly efficient, simple, clean, and eco-friendly protocol was used for the facile synthesis of charge-transfer complexes (CTCs) containing azithromycin and three π-acceptors: 7,7,8,8-tetracyanoquinodimethane (TCNQ), 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), and tetrafluoro-1,4-benzoquinone (TFQ). This protocol involves grinding bulk azithromycin as the donor (D) with the investigated acceptors at a 1:1 M ratio at room temperature without any solvent. We found that this protocol is environmentally benign, avoids hazardous organic solvents, and generates the desired CTCs with excellent yield (92–95%) in a straightforward means.