Ionic strength effect on deprotonation of para-sulfonatocalix[4]arene

Mohammad Faraji, Ali Farajtabar, Farrokh Gharib
2013 Journal of the Serbian Chemical Society  
The deprotonation of para-sulfonatocalix [4] arene was studied by a combination of spectrophotometric and potentiometric methods at 25 °C. The ionic strength of the solutions was kept constant by sodium perchlorate as a background electrolyte at 0.10-4.0 mol dm -3 . The spectral changes evidenced proton dissociation of only one hydroxyl group of calixarene in the studied pH range of 2-10. The pK a values were calculated using the STAR program by multivariate curve resolution of the absorbance
more » ... of the absorbance data. The results indicated that the acid-base behavior of para-sulfonatocalix[4]arene varied strongly with increasing ionic strength of the solution. The dependence of the deprotonation constant on ionic strength was explained by means of the Specific Ion Interaction Theory (SIT). The activity coefficients of the species were modeled using a modified SIT approach. The extracted specific ion interaction parameters were associated with the thermodynamic deprotonation constant of para-sulfonatocalix [4] arene.
doi:10.2298/jsc120706110f fatcat:wup4uspzsfbijapf47hfwtuwy4