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N , N ‐Dialkylaniline‐Substituted Tetraethynylethenes: A New Class of Chromophores Possessing an Emitting Charge‐Transfer State. Experimental and Computational Studies.
Author(s) -
Gobbi Luca,
Elmaci Nuran,
Lüthi Hans Peter,
Diederich François
Publication year - 2001
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/1439-7641(20010716)2:7<423::aid-cphc423>3.0.co;2-r
Subject(s) - moiety , chromophore , excited state , intramolecular force , chemistry , photochemistry , density functional theory , fluorescence , acceptor , computational chemistry , stereochemistry , atomic physics , optics , physics , condensed matter physics
Abstract The photophysical properties of N , N ‐dimethylaniline‐ (DMA) substituted tetraethynylethene (TEE; 3,4‐diethynylhex‐3‐ene‐1,5‐diyne) and related derivatives were investigated in a joint experimental and computational study. Measurements of the electronic emission spectra showed that these novel chromophores display a dual fluorescence which strongly depends on solvent polarity. Computational studies suggest that the twisted intramolecular charge‐transfer state (TICT) model offers a possible explanation for the experimentally observed dual fluorescence. Time‐dependent density functional calculations revealed that the initial excited state reached upon photoirradiation relaxes to a lower‐energy TICT state in which either the dimethylamino group is twisted into an orthogonal position with respect to the remaining planar arylated TEE moiety or the entire DMA donor group takes an orthogonal orientation with respect to the rigid, planar TEE acceptor moiety. For the compounds investigated, the charge‐transfer state responsible for the strongly solvent‐dependent luminescence is directly connected with the initial excited state, namely, no crossing of states is involved.