Spectrophotometric study of formation, structure, stability and kinetics of charge-transfer complexation of iodine with 1,4,7,10,13,16-hexamethyl-1,4,7,10,13,16-hexaazacyclooctadecane in chloroform solution. Application of hard-modeling approaches and theoretical calculations

Charge-transfer chemistry of azithromycin, the antibiotic used worldwide to treat the coronavirus disease (COVID-19). Part I: Complexation with iodine in different solvents

“… The absorption band at ~364–372 nm was caused by the rapid formation of a tri-iodide ion (I 3 − ) in solution from the CT complexation. This blue-shifted iodine band is the characteristic absorption band of the asymmetric tri-iodide ion (I 3 − ) resulting from the formation of the AZM-I 2 complex [ 157 , 160 , 162 ]. The iodine band observed in the free iodine solution (505 nm for the CH 2 Cl 2 and C 6 H 5 Cl solvents and 517 nm for the CCl 4 solvent) hypsochromically shifted to 364–372 nm upon the addition of the AZM solution.…”

“…In these solvents, CT complexation proceeded through the formation of an asymmetric tri-iodide ion (I 3 − ), as evidenced by the appearance of a band at 364–372 nm that is characteristic of the I 3 − ion. The formation mechanism of the I 3 − ion involves three steps [ 1 , [157] , [158] , [159] , [160] , [161] , [162] ]:…”

“…Extensive research efforts have focused on the complexation of iodine with different types of electron n - and π - donors to form both weak and strong CT complexes. It forms a large number of complexes with a wide variety of heterocyclic, aliphatic, and aromatic molecules [ [145] , [146] , [147] , [148] , [149] , [150] , [151] , [152] , [153] , [154] , [155] , [156] , [157] , [158] , [159] , [160] , [161] , [162] , [163] , [164] , [165] , [166] , [167] ]. The purpose of this study was to characterize the CT interaction of AZM with iodine in four different solvents: CH 2 Cl 2 , CHCl 3 , CCl 4 , and C 6 H 5 Cl.…”