Water-soluble, self-assembled nanocapsules composed of a functional bilayer membrane and enclosed guest molecules can provide smart (that is, condition responsive) sensors for a variety of purposes. Owing to their outstanding optical and redox properties, perylene bisimide chromophores are interesting building blocks for a functional bilayer membrane in a water environment. Here, we report water-soluble perylene bisimide vesicles loaded with bispyrene-based energy donors in their aqueous interior. These loaded vesicles are stabilized by in situ photopolymerization to give nanocapsules that are stable over the entire aqueous pH range. On the basis of pH-tunable spectral overlap of donors and acceptors, the donor-loaded polymerized vesicles display pH-dependent fluorescence resonance energy transfer from the encapsulated donors to the bilayer dye membrane, providing ultrasensitive pH information on their aqueous environment with fluorescence colour changes covering the whole visible light range. At pH 9.0, quite exceptional white fluorescence could be observed for such water-soluble donor-loaded perylene vesicles.

Perylene bisimides (PBIs) have been extensively studied as building blocks for functional supramolecular architectures in nonpolar solvents through hydrogen bonding, metal ion coordination, and π-π stacking interaction. 1 In contrast, little attention was paid to the self-assembly behavior of PBIs in aqueous solution. 2 Amphiphilic molecules, consisting of hydrophobic and hydrophilic moieties, self-assemble into highly organized aggregates with various morphologies such as spherical micelles, wormlike micelles, spherical and hollow vesicles, planar bilayers, nanotubes, and others. 3 The formation of these morphologies depends on solvent environments, molecular structures and shapes, as well as the relative fraction of hydrophilic and hydrophobic parts. 4 On the other hand, the stabilization of self-assembled superstructures through covalent linkage, for example, by polymerization, is of great interest for the practical application of supramolecular chemistry. 5 By covalent stabilization, the aggregate dimension and shape can be captured, and aggregate strength can be increased. 6 Here, we report for the first time that the nanoaggregates of perylene bisimides with particular morphology can be obtained by self-assembly of differently shaped amphiphilic PBIs in aqueous solution.In this work, the wedge-and dumbbell-shaped amphiphilic perylene bisimides PBI 1-4 (Chart 1) were synthesized and fully characterized (see details in Supporting Information). The absorption and fluorescence spectra of molecularly dissolved PBI 1-4 display a mirror-image relationship with a small Stokes' shift (5-6 nm) in "good" solvents such as CH 2 Cl 2 and THF (Figure S-15 in Supporting Information). Upon addition of the "bad" solvent water into the THF solution, a gradual decrease in fluorescence intensity at 500-600 nm was observed as exemplified for PBI 1 (Figure 1), and a new broad and structureless fluorescence band appears at 600-800 nm owing to excimer formation. 7 These observations imply that monomeric PBI 1 self-assembles into fluorescent multimolecular aggregates in aqueous solution.For the wedge-shaped PBI 1, Israelachvili's critical packing parameter (P c ) 8 was calculated to be 0.252, implying that spherical micelles should be favorably formed in polar solvents (P c < 1 / 3 for micelle formation). 8a The theoretical prediction was confirmed by transmission electron microscopic (TEM) studies. A large number of spherical micelles with the diameter of 4-6 nm were observed for PBI 1 in THF-containing water (2%, v/v) as shown in Figure 2a. The micelles were formed with a narrow polydispersity and a high degree of curvature due to the conical structure. The same aggregation behavior was also observed for PBI 2. In contrast, dumbbell-shaped PBI 4 self-assembled into rod aggregates with a diameter of 4 nm (Figure 2b). The formation of well-defined aggregates of these PBIs may be attributed to the π-π stacking interaction between the perylene cores along one-dimensional long axis without curvature, and stabilized by surrounding hyd...

Perylene bisimides are among the most valuable functional dyes and have numerous potential applications. As a result of their chemical robustness, photostability, and outstanding optical and electronic properties, these dyes have been applied as pigments, fluorescence sensors, and n-semiconductors in organic electronics and photovoltaics. Moreover, the extended quadrupolar π system of this class of dyes has facilitated the construction of numerous supramolecular architectures with fascinating photophysical properties. However, the supramolecular approach to the formation of perylene bisimide aggregates has been restricted mostly to organic media. Pleasingly, considerable progress has been made in the last few years in developing water-soluble perylene bisimides and their application in aqueous media. This Review provides an up-to-date overview on the self-assembly of perylene bisimides through π-π interactions in aqueous media. Synthetic strategies for the preparation of water-soluble perylene bisimides and the influence of water on the π-π stacking of perylene bisimides as well as the resulting applications are discussed.

A new perylene bisimide dye has been synthesized that forms highly fluorescent J‐aggregates in various organic solvents and its gelation in polar solvents like acetone and dioxane is observed (see figure), whilst anisotropic highly viscous lyotropic mesophases are created in apolar solvents such as n‐hexane or methylcyclohexane.

Water-soluble perylene tetracarboxylic acid bisimides (PBIs) with terminally linked polyglycerol dendrons of four different generations have been synthesized. These PBI dyes reveal a strong dendritic effect, enabling outstanding fluorescence quantum yields in water up to almost 100% for the highest dendron generation.

New synthetic methodologies for the formation of block copolymers have revolutionized polymer science within the last two decades. However, the formation of supramolecular block copolymers composed of alternating sequences of larger block segments has not been realized yet. Here we show by transmission electron microscopy (TEM), 2D NMR and optical spectroscopy that two different perylene bisimide dyes bearing either a flat (A) or a twisted (B) core self-assemble in water into supramolecular block copolymers with an alternating sequence of (AmBB)n. The highly defined ultralong nanowire structure of these supramolecular copolymers is entirely different from those formed upon self-assembly of the individual counterparts, that is, stiff nanorods (A) and irregular nanoworms (B), respectively. Our studies further reveal that the as-formed supramolecular block copolymer constitutes a kinetic self-assembly product that transforms into thermodynamically more stable self-sorted homopolymers upon heating.

PAMAM dendrimers of the zeroth to fifth generation (G0-5) have been peripherally modified with phenyl, naphthyl, pyrenyl, and dansyl chromophores. Their fluorescence behaviors are strongly affected by the dendritic architectures at different generations. These dendrimers modified with hydrophobic chromphores can self-organize into vesicular aggregates at the low generations G0-3 in water. The size and aggregation number of these vesicles decrease with increasing generation from G0 to G3. Critical aggregation concentration determined by fluorescence spectroscopy reveals that these aggregates can be favorably formed in the order of G3 > G2 > G1. In contrast to the vesicles made from traditional amphiphilic compounds, these dendrimer-based vesicles are very adhesive due to the H-bonding interaction and entanglement of dendritic branches located in the outer layer. A large number of multivesicle assemblies, i.e., "twins" and "quins" consisting of two and five vesicles, were clearly identifiable with transmission electron (TEM) and atomic force microscopy. For the dendrimers with peripheral pyrenyl chromophores, triangle-like vesicles were observed in water. The hydrophobic interphase thickness of the vesicular bilayer is ca. 2.0-3.2 nm determined by fluorescence resonance energy transfer methods, which agrees well with the thickness directly observed with TEM.

Conductive tubes: Self-assembled nanotubes of a bacteriochlorophyll derivative are reminiscent of natural chlorosomal light-harvesting assemblies. After deposition on a substrate that consists of a non-conductive silicon oxide surface (see picture, brown) and contacting the chlorin nanowires to a conductive polymer (yellow), they show exceptional charge-transport properties.