Comparative binding studies with a tetraurea picket porphyrin receptor using 1H NMR and isothermal titration calorimetry

Abstract

The (α, α, α, α)-5,10,15,20-tetrakis(2-(4-fluorophenylurea)phenyl)porphyrin binds strongly (K(M-1)>104) to the chloride anion and close to 2-3 orders of magnitude less to the acetate anion, in DMSO-d6 as revealed by 1H NMR titration studies. However, the acetate anion showed stronger binding than the chloride anion when ITC analyses were done. Thus, the binding studies' results vary with the use of instrumental method. Other significant differences and similarities observed in the behavior of anion binding with the porphyrin receptor when using the two probes will also be addressed in this report.