“…Of the many aromatic acceptors that have been investigated by spectroscopic methods, pyridinium cations have been studied especially extensively (Kosower, 1956;Verhoeven, Dirkx & DeBoer, 1970;Mackay, Landolph & Poziomek, 1971;Kosower & Skorcz, 1960;Mackay & Poziomek, 1972;Cozzens & Gover, 1970;Kosower, 1955;Rembaum, Hadek & Yen, 1971 ;Bradshaw & Deranleau, 1970;Cilento & Tedeschi, 1961;Alivisatos, Ungar, Jibril & Mourkides, 1961;Robbins & Holmes, 1972;Deranleau & Schwyzer, 1970;Cilento & Zinner, 1968;Shifrin, 1965Shifrin, , 1969Kosower, 1960;Shifrin, 1968), usually as iodide chargetransfer complexes (Kosower, 1956;Verhoeven, Dirkx & DeBoer, 1970;Mackay, Landolph & Poziomek, 1971 ;Kosower & Skorcz, 1960;Mackay & Poziomek, 1972;Cozzens & Gover, 1970;Kosower, 1955;Shifrin, 1969). Of the pyridinium cations, particular attention has been given to the acceptor properties of substituted nicotinamide derivatives (Bradshaw & Deranleau, 1970;Cilento & Tedeschi, 1961;Alivisatos, Ungar, Jibril & Mourkides, 1961;Robbins & Holmes, 1972;Deranleau & Schwyzer, 1970;Cilento & Zinner, 1968;Shifrin, 1965Shifrin, , 1969Kosower, 1960;…”