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Triplet MLCT Photosensitization of the Ring‐Closing Reaction of Diarylethenes by Design and Synthesis of a Photochromic Rhenium( I ) Complex of a Diarylethene‐Containing 1,10‐Phenanthroline Ligand
Author(s) -
Ko ChiChiu,
Kwok WaiMing,
Yam Vivian WingWah,
Phillips David Lee
Publication year - 2006
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.200501325
Subject(s) - photochromism , photochemistry , diarylethene , rhenium , chemistry , ligand (biochemistry) , intramolecular force , excited state , ultrafast laser spectroscopy , spectroscopy , inorganic chemistry , stereochemistry , biochemistry , physics , receptor , quantum mechanics , nuclear physics
Abstract Synthesis of the diarylethene‐containing ligand L1 based on Suzuki cross‐coupling reaction between thienyl boronic acid and the dibromophenanthroline ligand is reported. On coordination to the rhenium( I ) tricarbonyl complex system, the photochromism of L1 could be photosensitized and consequently extended from intraligand excitation at λ ≤340 nm in the free ligand to metal‐to‐ligand charge‐transfer (MLCT) excitation at λ ≤480 nm in the complex. The photochromic reactions were studied by 1 H NMR, UV/Vis, and steady‐state emission spectroscopy. Photosensitization was further probed by ultrafast transient absorption and time‐resolved emission spectroscopy. The results provided direct evidence that the formation of the closed form by the MLCT‐sensitized photochromic process was derived from the 3 MLCT excited state. This supports the photosensitization mechanism, which involves an intramolecular energy‐transfer process from the 3 MLCT to the 3 IL(L1) state that initiated the ring‐closure reaction. The photophysical and electrochemical properties of the complex were also investigated.