The (α, α, α, α)-5,10,15,20-tetrakis(2-(4-fluorophenylurea)phenyl)porphyrin binds strongly (K(M⁻¹)>10⁴) to chloride anion, and close to 2-3 orders of magnitude less to acetate anion, in DMSO-d₆ as revealed by ¹H NMR titration studies. However, acetate anion showed stronger binding than 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.