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Establishing the Critical Role of Oriented Aggregation in Molecular Solid State Fluorescence Enhancement
Author(s) -
Srujana P.,
Radhakrishnan T. P.
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201705041
Subject(s) - intermolecular force , intramolecular force , fluorescence , molecule , excited state , chemical physics , quenching (fluorescence) , förster resonance energy transfer , relaxation (psychology) , chemistry , materials science , atomic physics , stereochemistry , organic chemistry , physics , psychology , social psychology , quantum mechanics
The general occurrence of fluorescence emission quenching in molecular aggregates is circumvented in select classes of molecules. This has largely been attributed to the rigidification of the molecule and its environment, which hinders non‐radiative excited state energy loss through structural relaxation; since such an effect should in principle apply to most aggregates and crystals, there must clearly be other critical factors that make the select molecules exceptional. Discovery of three crystalline structures of a new push–pull molecule in its enantiomorphic and racemic forms, exhibiting not only very high, but distinctly different solid state fluorescence enhancements, has now allowed a systematic investigation of the role of intramolecular and intermolecular excited state energy loss pathways. Crystallographic, spectroscopic and computational investigations provide a detailed appraisal of the assembly patterns in the crystals, and rigorous establishment of an inverse correlation between intermolecular energy transfer and solid state fluorescence. The study provides a clear visualization of the critical role of oriented molecular aggregation in solid state fluorescence efficiency enhancement.