Synthesis, experimental and theoretical studies on the factors influencing the pKa values of new crown ethers containing a diarylphosphinic acid unit

Abstract

Synthesis of acidic new crown ethers containing a diarylphosphinic acid unit has been accomplished. The aromatic rings of the crown ethers were substituted with tertbutyl and nitro groups. Nitro substitution of the crown ethers was investigated. pKa determination of the new proton-ionizable crown ethers has been performed, showing the effect of the substituents of the aromatic rings on the acidity. An anomaly was discovered in the pKa values and an explanation was given based on quantum mechanical calculations and molecular dynamics simulations.