Centro Interdisciplinar de Investigação Bioquímica, Universidade de Mogi das Cruzes, 200, Mogi das Cruzes-SP, 08780-911, Brazil.
J Phys Chem A. 2009 Mar 5;113(9):1747-52. doi: 10.1021/jp808383e.
Aqueous solutions of N,N'-bis(2-phosphonoethyl)-3,4,9,10-perylenediimide (PPDI) were titrated with sodium dithionite, generating radical anions (PPDI(-)) and dianions (PPDI(2-)). In aqueous ethanol (1:1 v/v), PPDI existed as monomers and remained in the monomeric form in all reduced states. In water, on the other hand, PPDI formed dimers, which were transformed into a pi-stacked aggregated form upon one-electron reduction to PPDI(-). Addition of a second electron, however, resulted in dissociation of the aggregates, giving the dianion PPDI(2-) in the monomeric form. The presence of CTAB micelles prevented the aggregation of PPDI(-) in water, indicating that the radical anions were incorporated into the micellar phase. Reduction of PPDI in ethanol solution, where the dye was aggregated, resulted in the formation of soluble mixed stacks containing both PPDI(-) and PPDI(2-). These mixed stacks stabilized the radical anion form, preventing further reduction to the dianion.
N,N'-双(2-膦酸乙基)-3,4,9,10-苝二酰亚胺（PPDI）的水溶液用连二亚硫酸钠滴定，生成自由基阴离子（PPDI(-)）和二阴离子（PPDI(2-)）。在水和乙醇（1:1v/v）的混合溶液中，PPDI 以单体形式存在，并且在所有还原态下仍保持单体形式。另一方面，在水中，PPDI 形成二聚体，当被还原为 PPDI(-)时，这些二聚体转化为π堆积的聚集形式。然而，加入第二个电子会导致聚集物的解离，形成单体形式的二阴离子 PPDI(2-)。CTAB 胶束的存在阻止了 PPDI(-)在水中的聚集，表明自由基阴离子被掺入胶束相中。在乙醇溶液中还原 PPDI，其中染料聚集，导致形成含有 PPDI(-)和 PPDI(2-)的可溶性混合堆积物。这些混合堆积物稳定了自由基阴离子形式，防止进一步还原为二阴离子。
