Intermolecular Electron Transfer in Low-Molecular-Weight Polyaniline Models Associating on Protonation by Amphiphilic Acid in Organic Solvent

• Published in: Macromolecules 2001-07, Vol.34 (16), p.5480-5486
• Main Authors: Lokshin, Natalya A, Pyshkina, Olga A, Golubev, Vladimir B, Sergeyev, Vladimir G, Zezin, Alexander B, Kabanov, Victor A, Levon, Kalle, Piankijsakul, Somkiat
• Format: Article
• Language: English
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma002085u

Protonation of N-(4-aminophenyl)-N-{4-[(4-aminophenyl)imino]-2,5-cyclohexadien-1-yliden}-1,4-benzediamine and N-[4-(dimethylamino)phenyl]-N-(4-{[4-(dimethylamino)phenyl]imino}-2,5-cyclohexadien-1-ylidene)amine as trianiline models of polyaniline emeraldine base (PANI-EB) with dodecylbenzenesulfonic acid (DBSAH), a typical organo-soluble acidic dopant, in chloroform and 1-methyl-2-pyrrolidinone solutions, and also interaction of the resulting products with distearyldimethylammonium chloride (DDAC) as a potential dedoping agent were studied at ambient temperature by UV−vis and ESR spectroscopic methods. It has been shown that protonation is followed by intermolecular proton−electron transfer and results in the formation of monoradical cations apparently paired with the counterions which tend to associate even in rather dilute chloroform solutions and form aggregates characterized by intermolecular electron interchange. These aggregates, however, dissociate on adding an excess of the protonating agent, revealing an ESR signal line with resolved hyperfine structure which corresponds to a monoradical with unpaired electron interacting with two N nuclei. The proposed reaction mechanism probably can be applied to doping higher oligoanilines and PANI-EB. It is also shown that the protonated trimer complexes can be deprotonated (“dedoped”) in chloroform solution on adding DDAC. This is in contrast to PANI-EB doped with DBSAH, which could not be deprotonated with cationic amphiphiles.