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Self‐Assembly of Oligo( para ‐phenylenevinylene)s through Arene—Perfluoroarene Interactions: π Gels with Longitudinally Controlled Fiber Growth and Supramolecular Exciplex‐Mediated Enhanced Emission
Author(s) -
Babu Sukumaran S.,
Praveen Vakayil K.,
Prasanthkumar Seelam,
Ajayaghosh Ayyappanpillai
Publication year - 2008
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.200801255
Subject(s) - excimer , supramolecular chemistry , quenching (fluorescence) , stacking , photochemistry , fluorescence , hydrogen bond , fiber , excited state , self assembly , materials science , chemistry , polymer chemistry , crystallography , nanotechnology , molecule , organic chemistry , crystal structure , optics , physics , nuclear physics
The arene–perfluoroarene (Ar H –Ar F ) interaction, which has been extensively studied in the field of solid‐state chemistry, is exploited in the hierarchical self‐assembly of oligo( para ‐phenylenevinylene)s (OPVs) with controlled longitudinal fiber growth that leads to gelation. The size of the self‐assembled fibers of a pentafluorophenyl‐functionalized OPV 5 could be controlled through C‐F⋅⋅⋅HC hydrogen bonding and π stacking. The ability of fluoroaromatic compounds to form excited‐state complexes with aromatic amines has been utilized to form a supramolecular exciplex, exclusively in the gel state, that exhibits enhanced emission. Thus, the commonly encountered fluorescence quenching during the self‐assembly of OPVs could be considerably prevented by exciplex formation with N , N ‐dimethylaniline (DMA), which only occurred for the fluorinated OPV and not for the non‐fluorinated analogue 4 . In the former case, a threefold enhancement in the emission intensity could be observed in the gel state, whereas no change in emission occurred in solution. Thus, the major limitations of spontaneous fiber growth and fluorescence self‐quenching encountered in the self‐assembly of OPVs could be controlled to a great extent by using the versatile Ar H –Ar F interaction.