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Null Exciton Splitting in Chromophoric Greek Cross (+) Aggregate
Author(s) -
Sebastian Ebin,
Philip Abbey M.,
Benny Alfy,
Hariharan Mahesh
Publication year - 2018
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201810209
Subject(s) - exciton , chromophore , stacking , conjugated system , chemical physics , materials science , photonics , chemistry , coupling (piping) , dipole , j aggregate , hyperpolarizability , molecular physics , optoelectronics , polymer , molecule , photochemistry , condensed matter physics , physics , organic chemistry , composite material , polarizability , metallurgy
Exciton interactions in molecular aggregates play a crucial role in tailoring the optical behaviour of π‐conjugated materials. Though vital for optoelectronic applications, ideal Greek cross‐dipole ( α =90°) stacking of chromophores remains elusive. We report a novel Greek cross (+) assembly of 1,7‐dibromoperylene‐3,4,9,10‐tetracarboxylic tetrabutylester (PTE‐Br 2 ) which exhibits null exciton coupling mediated monomer‐like optical characteristics in the crystalline state. In contrast, nonzero exciton coupling in X‐type ( α =70.2°, PTE‐Br 0 ) and J‐type ( α =0°, θ =48.4°, PTE‐Br 4 ) assemblies have perturbed optical properties. Additionally, the semi‐classical Marcus theory of charge‐transfer rates predicts a selective hole transport phenomenon in the orthogonally stacked PTE‐Br 2 . Precise rotation angle dependent optoelectronic properties in crystalline PTE‐Br 2 can have consequences in the rational design of novel π‐conjugated materials for photonic and molecular electronic applications.