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چکیده
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In this study, charge transfer complexes of chlorpheniramine as electron donor with iodine as σ- acceptor and 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) as π-acceptor have been investigated spectrophotometrically in chloroform, dichloromethane and 1,2-dichloroethane solvents. Soft-modelling exploratory data analysis has been performed to get information about the number of species as well as concentration and spectral profiles of each individual species involved in the multivariate monitored process without the need of any prior assumption about the system. The results indicated that in the case of iodine the triiodide ion (I3 -) is formed after slow transformation of the initially formed outer complex to an inner complex and then fast reaction of the inner complex with iodine. In the case of DDQ, immediate formation of an electron donor-acceptor (EDA) complex is followed by two relatively slow consecutive reactions. The rate constants of the reaction have been obtained from the two-way kinetic-spectral data by using hard-modelling approach for chlorpheniramin-DDQ system and rank annihilation factor analysis (RAFA) for chlorpheniramin- iodine system. The stoichiometry of the complexes were found to be 1:1 and 1:2 for the chlorpheniramine:iodin system and the chlorpheniramine:DDQ system by job’s method of continuous variation respectively. The formation constants and molar absorption coefficients for chlorpheniramin-iodine complexes were determined from the Benesi-Hildebrand equation and for the chelorpheniramine-DDQ complexes from the mole ratio method. The influences of solvent properties on the formation constant of the resulting charge transfer complexes were discussed. The stability of the complex increases significantly by increasing polarity of the solvents. In the case of chlorpheniramin-DDQ complex initial structures and also complex structures were optimized by Gaussian 09 set of propgrams using B3LYP method and def2-SVP basis set and discussed.
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