Two Orthogonal Halogen‐Bonding Interactions Directed 2D Crystalline Supramolecular J‐Dimer Lamellae

Abstract

Dye assemblies exhibit fascinating properties and performances, both of which depend critically on the mutual packing arrangement of dyes and on the supramolecular architecture. Herein, we engineered, for the first time, an intriguing chlorosome‐mimetic 2D crystalline J‐dimer lamellar structure based on halogenated dyes in aqueous media by employing two distinct orthogonal halogen‐bonding (XB) interactions. As the only building motif, antiparallel J‐dimer was formed and stabilized by single π‐stacking and dual halogen⋅⋅⋅π interactions. With two substituted halogen atoms acting as XB donors and the other two acting as acceptors, the constituent J‐dimer units were linked by quadruple highly‐directional halogen⋅⋅⋅halogen interactions in a staggered manner, resulting in unique 2D lamellar dye assemblies. This work champions and advances halogen‐bonding as a remarkably potent tool for engineering dye aggregates with a controlled molecular packing arrangement and supramolecular architecture.

Molecularly Engineered Hierarchical Nanodisc from Antiparallel J‐stacked BODIPY Conjugates: Application to Theranostics with Mutually Beneficial Properties

“…The two chlorine atoms substituted at the 2,6‐positions of BODIPY are expected to provide XB interactions to drive and stabilize the dye aggregation with highly ordered molecular arrangements in water. [ 16 ] Notably, a bulky substituent was anchored at the meso ‐position of the BODIPY component of BD‐Gd with the aim of preventing close face‐to‐face H‐stacking while facilitating J‐stacking of BODIPY components. [ 2b,20 ]…”

“…Transmission electron microscopy (TEM) and atomic force microscopy (AFM) results revealed a morphology of random nanosheet material approximately 3.5 nm thick (Figure 2d,e). Compared with the thermodynamically stable self‐assembly of chlorinated BODIPY analogue (BDP‐Cl) driven by highly directional XB interactions (Figure 2b), [ 16 ] the absorption band and morphology of the BD‐Gd nanosheet indicate that it should be a kinetically controlled nano‐assembly. [ 8 ] As expected, after heat treatment (see Supporting Information), a ribbonlike nano‐lamella with a thickness of ≈6.6 nm and a length in micrometer scale was observed by TEM and AFM (Figure 2f,g), which is almost identical to that of the crystalline self‐assembly of BDP‐Cl.…”

“…Herein, we present a molecularly engineered hierarchical nanodisc by the antiparallel J‐aggregation of amphiphilic dye‐functional group conjugates, which exhibits improved photophysical properties compared to those of monomeric dyes and better performance than that of monomeric functional groups ( Figure ). As depicted in Figure 1a, the highly directional halogen bonding (XB) interaction, which has recently emerged as a potent driving force for the construction of supramolecular materials with highly ordered molecular arrangements, [ 14–16 ] enables a unique antiparallel J‐stacking of the amphiphilic BODIPY‐functional group conjugate, allowing an alternating and orderly arrangement of the hydrophilic functional groups on the two surfaces of the self‐assembled nano‐ribbon. We also propose that the size and morphology of J‐aggregate‐based self‐assemblies could be readily tuned by passing them through nano‐sized pores with the aid of an amphiphilic diblock copolymer (Figure 1b).…”

Halogen‐Bonded BODIPY Frameworks with Tunable Optical Features**

“…Interestingly, two absorption bands were observed between 510–530 and 580–600 nm for all B1‐B4 and B4‐II , unlike in their solution spectra. The band at 510–530 nm is attributed to the S 0 –S 1 transition, whereas the second absorption bands at 580–600 nm are possibly due to some aggregation involving J‐aggregation with panchromatic property [30] . In addition, two polymorph structures B4 and B4‐II exhibit different absorption profiles as seen in Figure 7.…”

“…However, the design of efficient supramolecular architectures with highly complex structures, such as BODIPY, presents a great challenge and requires comprehensive knowledge of noncovalent interactions. Recently, a few studies have reported observation of the XB interaction in their BODIPY structures [28–31] …”