Selective anion recognition by novel 5,10,15,20-tetrakis(o-ferrocenylcarbonylaminophenyl-substituted) zinc metalloporphyrin receptors

Abstract

New free-base and zinc-metallated 5,10,15,20-tetrakis(o -ferrocenylcarbonylaminophenyl-substituted) porphyrin atropisomers have been prepared. Proton NMR anion-binding investigations revealed the free-base porphyrins to be poor complexing agents for anions. The zinc metalloporphyrin receptors, however, strongly complex halide, nitrate and hydrogensulfate anions and stability-constant evaluations showed marked selectivity trends dependent upon the particular atropisomer. Electrochemical studies showed that these zinc metalloporphyrin receptors electrochemically sense anions via significant cathodic perturbations of the respective porphyrin oxidation and ferrocene redox couples.