Prospects of electroanalytical investigations of supramolecular complexes of a bis-crown stilbene with viologen-like compounds bearing two ammonioalkyl groups

Complexation of the bis-(18-crown-6) stilbene with viologen-like compounds, 1,2-bis{4-[N-(3-ammoniopropyl)pyridylium]}ethylene, 1,2-bis{4-[N-(2-ammonioethyl)pyridylium]}ethylene, 1,2-bis{4-[N-(3-ammoniopropyl)pyridylium]}ethane, and 1,2-bis{3-[N-(3-ammoniopropyl)pyridylium]}ethylene, bearing two ammonioalkyl groups has been studied in MeCN solutions using cyclic voltammetry and UV–vis spectroscopy. The bis-crown stilbene was found to form strong 1:1 charge-transfer complexes, with the viologen-like diammonium compounds via two-site H-bonding. The complexation results in a considerable positive shift of the first oxidation potential of the electron donor bis-(18-crown-6) stilbene molecule ranging from 160 to 240 mV depending on the nature of the diammonium viologen-like compounds. The magnitude of this shift was used as a measure of the thermodynamic stability of bimolecular complexes between bis-crown stilbene and these viologen-like compounds. The relative contributions of H-bonding and charge-transfer interactions on the complex stability are discussed.