FREE-RADICAL FORMATION IN REACTIONS OF LECITHIN WITH TETRACYANOQUINODIMETHANE AND TETRACYANOETHYLENE - RELATING THE BEHAVIOR OF MEMBRANE-PARTITIONED ELECTROCHEMICAL-CELLS TO CHARGE-CARRIER USING ELECTRON-SPIN-RESONANCE

Electron spin resonance spectra of solutions used to make conductive b ilayer lipid membranes reveal that free radical formation is a precurs or to membrane conductivity. Tetracyanoquinodimethane (TCNQ) forms a s table radical that self-aggregates in nonaqueous media, yet will diffu se into the aqueous phase as a monomer, potentially allowing interfaci al exchange. Tetracyanoethylene (TCNE) will undergo hydrolysis via a r adical intermediate, and the decomposition product is ESR silent. The electrochemical response of an electrochemical cell partitioned by a m embrane modified by these dopants is ionic for TCNE. Although the mech anism is less clear for TCNQ, the role of a stable radical is clearly implicated. (C) 1997 Academic Press.