Three-dimensional Structure of J Aggregates of Pseudoisocyanine Chloride Dyes at a Mica/Solution Interface Revealed by AFM

Abstract

By using tapping-mode atomic force microscopy (AFM), we revealed for the first time the structure of J aggregates of pseudoisocyanine chloride(PIC-Cl) dyes at a mica/solution interface in an aqueous PIC-Cl solution. The J aggregates were leaf-like islands in multilayers of PIC-Cl molecules. The minimal size of the aggregate necessary for the J band was also revealed. Dye molecules grow into the J aggregates at a mica/solution interface by a Volmer-Weber type growth process.

Anisotropic Growth of J Aggregates of Pseudoisocyanine Dye at a Mica/Solution Interface Revealed by AFM and Polarization Absorption Measurements

“…In previous studies, we solved this difficulty by using tapping mode atomic force microscopy (TM-AFM) and revealed for the first time the real structure of the J aggregate of PIC-Cl at a mica/liquid interface in an aqueous PIC-Cl solution. 16,17 Contrary to previously accepted models in which J aggregates at a mica/solution interface have two-dimensional monolayer structures, 7,8 our AFM images showed that the aggregates have three-dimensional leaf-like island structures. Furthermore, the morphological change revealed by AFM imaging suggests that the J aggregates grow by a Volmer-Weber type growth process.…”

“…Previous reports state that PIC−Cl forms J aggregates at a mica/solution interface when the concentration of PIC−Cl exceeds 1.0 × 10 -4 M. , We examined the growth process of these J aggregates in detail. Figure shows typical absorption spectra of aqueous PIC−Cl solutions . The spectra showed quasi-adsorption behavior (Figure , inset).…”

Spectral properties and structure of the J-aggregates of pseudoisocyanine dye in layered silicate films

“…The specific structures of the J -aggregates are typical of a head-to-tail intermolecular association between the molecular units [2]. Formation of the J -aggregates of PIC has been reported for various types of reaction systems, e.g., solutions [2,3] and interfaces [4]. Preference for the PIC cations to form J -aggregates rather than the generally more common H -aggregates is mainly due to the molecular structure of PIC (Fig.…”

5 Morphology transformations in solutions: dynamic supramolecular aggregates

“…We will discuss the growth processes of the mesoscopic aggregates based on in situ AFM measurements. [67][68][69] 4.1 Three-dimensional mesoscopic morphology of pseudoisocyanine J-aggregates at a mica/solution interface Fig. 21(a) shows an optical path length dependence on the absorption spectrum of an aqueous PIC solution (2.0 mM) in a custom-made cell.…”