4-oxocyclohexadienylidene Porphyrinogen as an Electrochemical Anion Receptor

Abstract. Sensitive and selective detection of biologically and environmentally important anions has been a vast growing field in supramolecular chemistry [1,2]. Much research has been devoted to designing sensors that can selectively recognize anions. Recently, we have reported an anionic and solvatochromatic sensor [5]. (Scheme 1) In this investigation, the effect of various anions on the redox states of the porphyrinogen and its N-substituted analogues were studied. Cyclic voltammetry (CV) was employed to probe the changes in the redox potentials of the receptors upon complexation with anions. Upon addition of Fto porphyrinogen, a cathodic shift of ~520 mV corresponding to 1Fcomplex was observed. The Fion had the greatest effect on the porphyrinogen redox potentials while other anions gave modest shifts. DFT computational studies on the anion binding correlated well with the electrochemical results.