Concerted Interplay of Excimer and Dipole Coupling Governs the Exciton Relaxation Dynamics in Crystalline Anthracenes

Abstract

Ac ombined theoretical and experimental investigation into the role of concerted long-(dipolec oupling) and short-range (orbitalo verlap mediated excimer) electronic interactions in modulating the emission of six crystalline acetylanthracenes( 1-3)i sr eported. Friedel-Crafts acylation of anthracene rendered crystalline acetylanthracenes with discrete close packing, varied orbitalo verlap, and resultant distinct emission (blue-green-yellow) from cooperative excimera nd dipole coupling. Time-resolved emission spectroscopy (TRES) studies and the Kasha's exciton theory based quantitative estimationo fd ipole coupling (mean-field approximation) substantiates the exciton dynamics in crystalline 1-3.E xtension of the Kasha'se xciton model beyond the traditional nearestneighbora pproach, and consistent agreement among the computed spectral shifts and TRES temporal components, corroborate ah olistic approach to decipher the exciton relaxationd ynamics in the molecular assembly of novel photonic materials. [a] A. M. Philip, Dr.M.H ariharan SchoolofC hemistry,Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

Exciton Isolation in Cross-Pentacene Architecture

“…Excitonic communication within self-assembled π-chromophoric systems has been a field of boundless curiosity since the pioneering study of dye aggregates by Jelley and Scheibe independently in the 1930s. − Variation in the excitonic and electronic coupling via changes in the relative spatial orientation and intermolecular distance within the stacked molecular assembly has potent implications on their optical and intrinsic charge-transport properties. − Kasha and co-workers conceived a theoretical relation between the molecular assembly and the photophysical properties approximately six decades ago . In the molecular exciton model developed by Kasha, exciton splitting is explained for diverse geometrical arrangements of the molecular dimer on the basis of the long-range Coulombic coupling .…”

Base‐Assisted Imidization: A Synthetic Method for the Introduction of Bulky Imide Substituents to Control Packing and Optical Properties of Naphthalene and Perylene Imides

“…We attribute the pronounced Stokes shift observed for 6 a and 6 c to a relaxation into excimers which originate from the “preformed” dimers in the solid state (Figure ). It is known that such “excimerization” is supported by nearly parallel alignments and a significant π–π‐contact surface as found in the crystals of these dyes (Figure a,c) . It is interesting to note that this relaxation process of photoexcited 6 a , c into excimers affords an increase of the fluorescence quantum yield by a factor greater than 30 for 6 a compared to the monomeric state in solution.…”

“…It is known that such "excimerization" is supported by nearly parallel alignments [32,33] and as ignificant p-p-contact surface as found in the crystals of these dyes (Figure 1a,c). [34] It is interesting to note that this relaxation process of photoexcited 6a,c into excimers affords an increase of the fluorescence quantum yield by af actor greater than 30 for 6a compared to the monomeric state in solution. Similar observations were made for naphthalene dicarboximide-based systems.…”

Decoding the Curious Tale of Atypical Intersystem Crossing Dynamics in Regioisomeric Acetylanthracenes

“…The synthesis, X-ray structural and the crystallographic details of the monoacetylanthracenes (1A, 1B, and 1C) are elaborated elsewhere (see Table S1). ,, The molecular structure obtained from the X-ray structural analysis suggests that 1A, 1B, and 1C vary not only in the position but also in the torsion along the carbonyl group (Scheme ). The derivatives 1A (θ = 27.5°) and 1B (θ = 6.40°) possess a carbonyl group nearly in the plane of the chromophore, whereas a relatively higher steric crowding in 1C renders the carbonyl group at a near-orthogonal (θ = 88.05°) geometry (Scheme ).…”