Spectrophotometric study of the charge transfer complexes of 4′-nitrobenzo-15-crown-5 and benzo-15-crown-5 with iodine in nonaqueous solvents

The formation of charge transfer complex between iodine with 4′-nitrobenzo-15-crown-5 (NB15C5) and benzo-15-crown-5 (B15C5) is investigated spectrophotometrically in chloroform and dichloromethane (DCM) solutions at 25 °C. The pseudo-first-order rate constants for the transformation process were evaluated from the absorbance-time data and found to vary in the order of DCM > CHCl3. The values of the formation constant, Kf, for each complex are evaluated from Benesi-Hilebrand equation. Stability of the resulting complex in two solvents was also found to vary in the order of DCM > CHCl3.