Mesoscopic structures of J aggregates of organic dyes at a solid/liquid interface and in solution: spectroscopic and microscopic studies

摘要

Supramolecular structures in J aggregate systems are characterized. J aggregates of a pseudoisocyanine dye (PIC) at a mica/solution interface were in situ observed by tapping-mode atomic force microscopy (AFM). The single aggregates possessed a three-dimensional disk-like island structure in a mesoscopic scale. The island size ranged ～400-600 nm long, ～100 nm wide, and ～3-6 nm high. Morphological differences can be observed between the J aggregates at a solid/liquid interface and those in bulk solution. Mesoscopic string structures of 5,5'-dichloro-3,3'-disulfopropyl thiacyanine (TC) J aggregates were detected in an aqueous solution for the first time by both fluorescence microscopy and microspectroscopy. The length of the J string was several tens of μm while the width was very narrow.