Journal
CHEMISTRY-A EUROPEAN JOURNAL
Volume 25, Issue 68, Pages 15615-15627Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/chem.201903814
Keywords
electron transfer; intersystem crossing; naphthalenediimide; photocatalysis; triplet photosensitizer
Categories
Funding
- NSFC [21673031, 21761142005, 2181101275, 21421005]
- Fundamental Research Funds for the Central Universities [DUT2019TA06]
- State Key Laboratory of Fine Chemicals [ZYTS201901]
Ask authors/readers for more resources
Oxoverdazyl (Vz) radical units were covalently linked to the naphthalenediimide (NDI) chromophore to study the effect of the radical on the photophysical properties, especially the radical enhanced intersystem crossing (REISC), which is a promising approach to develop heavy-atom-free triplet photosensitizers. Rigid phenyl or ethynylphenyl linkers between the two moieties were used, thus REISC and formation of doublet (D-1, total spin quantum number S=1/2) and quartet states (Q(1), S=3/2) are anticipated. The photophysical properties of the dyads were studied with steady-state and femtosecond/nanosecond transient absorption (TA) spectroscopies and DFT computations. Femtosecond transient absorption spectra show a fast electron transfer (<150 fs), and ISC (ca. 1.4-1.85 ps) is induced by charge recombination (CR, in toluene). Nanosecond transient absorption spectra demonstrated a biexponential decay of the triplet state of the NDI moiety. The fast component (lifetime: 50 ns; population ratio: 80 %) is assigned to the D-1 -> D-0 decay, and the slow decay component (2.0 mu s; 20 %) to the Q(1)-> D-0 ISC. DFT computations indicated ferromagnetic interactions between the radical and chromophore (J=0.07-0.13 eV). Reversible formation of the radical anion of the NDI moiety by photoreduction of the radical-NDI dyads in the presence of sacrificial electron donor triethanolamine (TEOA) is achieved. This work is useful for design of new triplet photosensitizers based on the REISC effect.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available