<b>Spectrophotometric and electrochemical studies of the interaction of cryptand 222 with DDQ and I₂ in ethanol solution</b>

Abstract

Spectrophotometric and electrochemical studies concerning the interaction of cryptand 222 with DDQ and I 2 have been performed in ethanol solution. In the case of DDQ, the results are indicative of the formation of C222 + and DDQthrough an equilibrium reaction. The results of I 2 indicate the formation of I 2-ethanol complex and I 3 in the absence of C222. In the presence of C222, the formation of C222I + and I 3 through a non-equilibrium reaction is confirmed. The equilibrium constant of the redox reaction between DDQ and C222 has been calculated from the absorbance mole ratio data, using the nonlinear least square program ''KINFIT''. The electrochemical reversibility of I-/I 2 couple and irreversibility of DDQ/DDQis indicated by amperometry. The behavior of DDQ and I 2 has been compared. A comparison with aprotic solvents has also been made.

New Charge Transfer Complexes of K+-Channel-Blocker Drug (Amifampridine; AMFP) for Sensitive Detection; Solution Investigations and DFT Studies

“…The λ max of one of the CT bands, i.e., 584 nm for the complex in ANCHCl 3 and 587 nm in ANDCM, was chosen for quantitative measurements to provide the highest sensitivity. The radical anion of DDQ, which is intensely purple-colored, was produced in the studied solvents systems as a result of complete charge transfer from the donor (AMFP) to the acceptor (DDQ), as suggested in Scheme 1 [ 36 , 37 ]. This situation appears to be caused by the strong e-donating nature of AMFP, and the high electron affinity of DDQ (1.9 eV) [ 35 ].…”

A rapid and simple colorimetric test for 2,2,2-cryptand (Kryptofix 2.2.2.) in solution

“…It has been suggested that depending on the mole ratio an inclusion complex of the type [1.I + ]I À or [1.I + ]I 3 À is possible, and the UV-vis spectra associated with every chemical specie have been characterized. [14][15][16][17] The UV-vis spectrum of a freshly prepared I 2 /I À solution exhibits three absorbance maxima at 353, 287 and 230 nm (see ESI †) which upon addition of a 50 ppm solution of 1 did not present obvious changes due to the formation of a new chemical specie, moreover the resulting spectrum presented a general saturation in different wavelengths even aer several dilutions.…”

Spectroscopic studies and molecular orbital calculations of charge transfer complexation between 3,5-dimethylpyrazole with DDQ in acetonitrile

“…The average values of both K CT and e calculated at the three wavelengths (447, 542 and 589 nm) were 5089 ± 180 L mol À1 and 3032 ± 96 L mol À1 cm À1 , respectively. The high value of electron affinity of DDQ [13], the high donating power of DMP (from the presence of two electronegative nitrogen atoms, two methyl groups and the ring p system) beside the high dielectric constant of acetonitrile are presumably responsible for the high value of stability constant of the complex. Furthermore, a good evidence of complex stability is confirming from the constant absorbance of Donor Acceptor CT complex …”

“…It is involved in processes of energy storage and utilization and therefore plays a vital role in biological reactions [13]. Some of these reactions are considered as simple models for biochemical processes [14].…”