Multi‐Channel Receptors and Their Relation to Guest Chemosensing and Reconfigurable Molecular Logic Gates

Abstract

AbstractThe synthesis and characterisation of a family of multi‐channel receptors containing crown‐cation binding sites anchored to a 1‐aminophenyl‐1,2,2‐tricyanoethylene group is reported. The ligands L1–L6 bear a 1‐aminophenyl‐1,2,2‐tricyanoethylene scaffolding which is simultaneously a redox‐active group (showing reduction processes at moderately modest potentials) and an acceptor moiety in the 1‐aminophenyl‐1,2,2‐tricyanoethylene chromophore. Additionally, dyes L1–L6 also show fluorescence emission. The colour variation of L1–L6 in acetonitrile in the presence of the metal cations Ag+, Cd2+, Cu2+, Fe3+, Hg2+, Pb2+ and Zn2+ has been studied. Selective hypsochromic shifts were found for the systems L4‐Pb2+, L5‐Hg2+ and L6‐Hg2+. For Hg2+ with L5 and L6 and Pb2+ with L4, emission fluorescence enhancements most likely associated with metal coordination to the anilinium nitrogen were observed. The electrochemical behaviour of receptors L1–L6 was studied in acetonitrile with platinum as working electrode and [Bu4N][BF4] as supporting electrolyte. This family of receptors shows a one‐electron reversible reduction process at around –0.70 V vs. SCE, attributed to the reduction of the tricyanovinyl group. Additionally, all the receptors also show the oxidation of the anilinium moiety at about 1.2–1.4 V vs. SCE. Significant anodic shifts of both reduction and oxidation waves were found in the presence of certain metal cations. The relationship of these multiple‐channel signalling receptors with guest chemosensing and reconfigurable molecular‐based logic gates is discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)