Discrete π-Stacks of Perylene Bisimide Dyes within Folda-Dimers: Insight into Long- and Short-Range Exciton Coupling

Abstract

Four well-defined π-stacks of perylene bisimide (PBI) dyes were obtained in solution by covalent linkage of two chromophores with spacer units of different length and sterical demand. Structural elucidation of the folda-dimers by in-depth nuclear magnetic resonance studies and geometry optimization at the level of density functional theory suggest different, but highly defined molecular arrangements of the two chromophores in the folded state enforced by the various spacer moieties. Remarkably, the dye stacks exhibit considerably different optical properties as investigated by UV/vis absorption and fluorescence spectroscopy, despite only slightly different chromophore arrangements. The distinct absorption properties can be rationalized by an interplay of long- and short-range exciton coupling resulting in optical signatures ranging from conventional H-type to monomer like absorption features with low and appreciably high fluorescence quantum yields, respectively. To the best of our knowledge, we present the first experimental proof of a PBI-based "null-aggregate", in which long- and short-range exciton coupling fully compensate each other, giving rise to monomer-like absorption features for a stack of two PBI chromophores. Hence, our insights pinpoint the importance of charge-transfer mediated short-range coupling that can significantly influence the optical properties of PBI π-stacks.

Near‐Infrared Circularly Polarized Luminescence through Intramolecular Excimer Formation of Oligo(p‐phenyleneethynylene)‐Based Double Helicates

“…The g lum of 1‐BN decreased in methanol at a higher concentration (1.0×10 −5 m ) (Table S6), indicating that the intermolecular chiral nanostructure formation, such as intermolecular excimer formation, had little effect on enhancing g lum . It is known that the tuning of π‐stacking orientation and the restriction of intramolecular rotation can enhance the quantum yield of intramolecular excimer photoluminescence up to 100 % . By enhancing the overlap of π‐orbitals in a rigid intramolecular excimer, the photoluminescence quantum yield Φ PL (excimer) will be improved without a decrease in the g lum value.…”

Facile Synthetic Route for Direct Access of Perylenediimide Single Crystals in High Yield through In Situ Crystallization

“…The control over PDIs molecular assembly provides opportunity to tune solid state absorption from visible to near infrared (NIR) range, and enhanced optoelectronic, electrochemical and charge transport properties . Computationally optimized PDIs structure and molecular assembly have often been used to correlate their structure and optoelectronic properties . However, single crystal structural analysis of PDIs are expected to provide better understanding of molecular assembly and structure‐property relationship in the bulk materials .…”

“…[34][35][36] Computationally optimized PDIs structure and molecular assembly have often been used to correlate their structure and optoelectronic properties. [37][38] However, single crystal structural analysis of PDIs are expected to provide better understanding of molecular assembly and structure-property relationship in the bulk materials. [39] Physical vapor transport (PVT) method is the mostly utilized method for growing single crystals of PDIs based materials.…”

Polymorphic Pure Organic Luminogens with Through‐Space Conjugation and Persistent Room‐Temperature Phosphorescence

“…Through-space conjugation can significantly impact the molecular conformation and charge-transfer properties of the compounds, [45,46] thus playing av ital role in the constructiono f functional materials for diverseo ptoelectronic applications, in- cluding multi-dimensional transport of carriers, organic fieldeffect transistors (OFETs), and luminescent materials. [45][46][47][48][49] Previousr eports on luminogens with through-space conjugation are mostly limited to fluorescence. [46,48,49] Only af ew scattered examples of nonconventional luminogens with al ack of remarkable conjugates have dealt with (p-)RTP emissions.…”

“…[45][46][47][48][49] Previousr eports on luminogens with through-space conjugation are mostly limited to fluorescence. [46,48,49] Only af ew scattered examples of nonconventional luminogens with al ack of remarkable conjugates have dealt with (p-)RTP emissions. [18,[50][51][52] In this contribution, we therefore investigated the Diels-Alder cycloaddition adduct of anthracene (AN) and maleic anhydride (MA), or AN-MA, which consists of two phenylg roups rich in p electrons and an anhydride moiety with abundant lone pairs (n)( Scheme 1).…”