Why Do Congo Red, Evans Blue, and Trypan Blue Differ in Their Complexation Properties?

摘要

Congo, Red, Evans Blue, and Trypan Dlue dyes were evaluated in terms of their ability to form supramolecular systems in water solution. A geometric transformation set was defined to construct a supramolecular model system composed of eight dye molecules. The stability of the constructed multimolecular systems was estimated by molecular dynamics using AMBER 4.1 and DISCOVER force fields. The results essentially confirm the tendency toward self-assembly in each case. However, Congo Red and Evans Blue were found to form stable, continuous, ribbon-like supramolecular organizations, whereas Trypan Blue self-assembly appeared defective; some additional deviations from planarity seem to be the main reason for the disturbance in self-assembling. The extra rotation around the azo bonds in the Trypan Blue molecule is slightly extorted by the close proximity of sulfonic groups. This may also be the direct cause of the observed deviation from symmetry in the molecule of this dye. The results cofirm that the self-assembling capability of the compounds studied correlates with ethe capacity to complex proteins, supporting the idea that supiramolecularity may create specific ligation properties.