Spectroscopic studies of charge-transfer complexation of iodine with a new benzo-substituted macrocyclic diamide in chloroform, dichloromethane and their 1:1 mixture

Abstract

Charge-transfer complexation of iodine with a new benzo-substituted macrocyclic diamide 5, 6,7,8,9,10-hexahydro-2H-1,13,4,7,10-benzodioxatriazacyclopentadecine-3,11(4H,12H)-dione (L) with iodine was studied spectrophotometrically in chloroform, dichloromethane and their 1:The observed time dependence of the charge-transfer band and subsequent formation of I 3 -ion are related to the slow formation of the initially formed 1:1 L.I 2 outer complex to an inner electron donor-acceptor (EDA) complex, followed by fast reaction of the inner complex with iodine to form a triiodide ion, as follows: L + I 2 o L.I 2 (outer complex), fast L.I 2 (outer complex) o (L.I + )I -(inner complex), slow (L.I + )I -(inner complex) + I 2 o (L.I + )I 3 -, fastThe pseudo-first-order rate constants for the transformation process were evaluated in different solvent systems. The stability constants of the resulting EDAr complexes were also evaluated and the solvent effect on their stability is discussed. The resulting complexes were isolated and characterized by FTIR and 1 H NMR spectroscopy.

Kinetic Study of Charge Transfer Complexes of Iodine With Some Crown Ethers in Nonaqueous Solvents

“…3 show the absorbance-time curves DB24C8.I 2 and B18C6.I 2 complexes in chloroform , dichloromethane and 1,2-dichloroethane solution. The above experimental observations seem to be in accord with the following mechanism, which has been proposed before [9][10][11][12][13]. The proposed mechanism for formation of the charge transfer complex as presented at the following:…”

“…The stability of these complexes appears to be related to the macrocycles , cavity sizes; It is at maximum when the cavity diameter matches the ionic size [8]. During the past two decades, a growing interest has been focused on the complexing ability of these macrocyclic ligands as electron-pair molecules towards neutral and, especially, molecular iodine [9][10][11][12][13]. Iodine has been found to form with many compounds charge transfer complexes whose properties have been thoroughly studied [14][15][16][17][18].…”

“…Various physico-chemical techniques such as: spectrophotometry [19,20], NMR spectrometry [21], polarography [22,23], potentiometry [24] and conductometry [25][26][27] have been used to study the complex formation between macrocyclic polyethers (crown ethers) and various metal cations in solutions. Following our previous report on the spectroscopic study of charge transfer complexes of crown ethers with iodine in different halocarbone solvents [9,10], in this paper we report here the results of a spectrophotometric investigation of the kinetics of complex formation of iodine with 15-crown-5 (15C5), dicyclohexyl-18-crown-6 (DC18C6), benzo-18-crown-6 (B18C6) and dibenzo-24-crown-8 (DB24C8) in chloroform, dichloromethane and 1,2-dichloroethane solutions.…”

Spectrophotometric Investigation of the Charge–Transfer Interaction of 2,3-Dicyano-1,4-naphthoquinone with N-Ethylaniline in Chlorinated Solvents

“…A substantial amount of work has been carried out to correlate the change in rates of the reactions with the nature and properties of the solvent. In many instances the rate of reaction increases with increases in dielectric constant of the medium [25,26]. In other cases, a decrease in rate of reaction with increasing dielectric constant has been reported [27,28].…”