Crystal Engineering of 1D Exciton Systems Composed of Single‐ and Double‐Stranded Perylene Bisimide J‐Aggregates

Abstract

Single crystals of three at bay area tetraphenoxy‐substituted perylene bisimide dyes are grown by vacuum sublimation. X‐ray analysis reveals the self‐assembly of these highly twisted perylene bisimides (PBIs) in the solid state via imide–imide hydrogen bonding into hydrogen‐bonded PBI chains. The crystallographic insights disclose that the conformation and sterical congestion imparted by the phenoxy substituents can be controlled by ortho‐substituents. Accordingly, whilst sterically less demanding methyl and isopropyl substituents afford double‐stranded PBI chains of complementary P and M atropo‐enantiomers, single hydrogen‐bonded chains of homochiral PBIs are observed for the sterically more demanding ortho‐phenyl substituents. Investigation of the absorption and fluorescence properties of microcrystals and thin films of these PBIs allow for an unambiguous interpretation of these exciton systems. Thus, the J‐aggregates of the double‐stranded crystals exhibit a much larger (negative) exciton coupling than the single‐stranded one, which in contrast has the higher solid‐state fluorescence quantum yield.

Chiral Perylene Bisimide Dyes by Interlocked Arene Substituents in the Bay Area

“…In 2 c the dihedral angles were found to be 32.7° and 33.4° respectively, while the difference is less pronounced in 6 a with 29.2° and 29.9° with the larger pyrene substituents. Such broken symmetry has been reported before for tetraphenoxy‐PBIs [38,39] where it is an intrinsic feature of the perylene core rather than a packing effect in the solid state [40] . The carbon‐carbon bond distances within the perylene core in all three molecules are comparable to previously reported PBIs.…”

Perspectives in Dye Chemistry: A Rational Approach toward Functional Materials by Understanding the Aggregate State

“…For dye aggregates and solid-state materials, however, the situation is more challenging, in particular because a large number of additional relaxation processes emerge due to dye–dye interactions. Indeed, for the solid state where a design of functional properties is most desirable for the optimization of materials properties, the situation is most difficult because even such an easily recognizable phenomenon like fluorescence quenching may have very different origins, such as a competing non-radiative relaxation process due to an interaction with a direct neighbor dye or the quenching of a highly mobile exciton at a defect site in the bulk or at the surface. , To differentiate such possibilities and to get insight into effects originating from dye–dye interactions, covalent and non-covalent dimers proved to be most useful and afforded a lot of insights during the past decade from a variety of studies in solution with sophisticated optical spectroscopies. In the following, we will discuss the relaxation pathways from the initially populated optically excited Frenkel exciton state (as discussed in the previous section) leading to excimers, symmetry-breaking charge separation (SBCS), and singlet fission (SF).…”

Coexistence of Parallel and Rotary Stackings in the Lamellar Crystals of a Perylene Bisimide Dyad for Temperature-Sensitive Bicomponent Emission

“…In the past decades, perylene bisimides (PBIs) were intensively investigated as building blocks for the construction of functional supramolecular assemblies based on the directional intermolecular π–π interactions and hydrogen bonding. , Numerous self-assembled aggregates and nanocrystals were fabricated with either H- or J-type coupling. − However, irrespective of the coupling, they still suffered from ACQ in condensed states. , One example is that singlet fission in the nanocrystals of bay-area nitro-substituted PBI with parallel intermolecular stacking resulted in efficient formation of nonradiative triplet excited states through an intermolecular symmetry-breaking charge separation (SB-CS) process …”

“…18−22 However, irrespective of the coupling, they still suffered from ACQ in condensed states. 23,24 One example is that singlet fission in the nanocrystals of bay-area nitro-substituted PBI with parallel intermolecular stacking resulted in efficient formation of nonradiative triplet excited states through an intermolecular symmetry-breaking charge separation (SB-CS) process. 25 Recently, PBI dyads and multiple PBIs linked through flexible spacers have been designed for the multidimensional assembly for application in photovoltaics 26−28 and photosynthetic systems; 29 however, the flexible molecular conformations reduce long-range ordered molecular stacking in the condensed solid state.…”