Synthesis and study on aggregation behaviours in liquid phase of three prepared cyanine dyes.

Here we investigate the aggregation behaviours of three prepared dyes in the liquid phase to pick out one possessing J-aggregation characteristic that is of significant interest for organic materials used in multiple bio-applications. The self-assembly of dyes usually leads to various forms of aggregates, for example, H-aggregates or J-aggregates and it is easy to distinguish bathochromic J-aggregation from hypsochromic H-aggregation using UV/vis light spectroscopy. Enlightened by the cyanine dyes that have shown a great tendency to self-associate, we designed and synthesized three cyanine dyes: Cy7-Ph, DCy7-Ph, and SN-Cy7-Ph, followed by the study of the influence of multiple factors on their aggregation behaviours, including solvent polarity, ionic strength, and temperature. Finally, we found that of the three molecules only SN-Cy7-Ph could self-assemble into J-aggregates conveniently and stably in the aqueous phase under normal conditions.