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. 2016 Nov 2;55(45):14009-14013.
doi: 10.1002/anie.201607373. Epub 2016 Oct 6.

Photoisomerization of Arylazopyrazole Photoswitches: Stereospecific Excited-State Relaxation

Ya-Ting Wang  1 , Xiang-Yang Liu  1 , Ganglong Cui  2 , Wei-Hai Fang  1 , Walter Thiel  3
Affiliations

Photoisomerization of Arylazopyrazole Photoswitches: Stereospecific Excited-State Relaxation

Ya-Ting Wang et al. Angew Chem Int Ed Engl. .

Abstract

Electronic structure calculations and nonadiabatic dynamics simulations (more than 2000 trajectories) are used to explore the Z-E photoisomerization mechanism and excited-state decay dynamics of two arylazopyrazole photoswitches. Two chiral S1 /S0 conical intersections with associated enantiomeric S1 relaxation paths that are barrierless and efficient (timescale of ca. 50 fs) were found. For the parent arylazopyrazole (Z8) both paths contribute evenly to the S1 excited-state decay, whereas for the dimethyl derivative (Z11) each of the two chiral cis minima decays almost exclusively through one specific enantiomeric S1 relaxation path. To our knowledge, the Z11 arylazopyrazole is thus the first example for nearly stereospecific unidirectional excited-state relaxation.

Keywords: arylazopyrazoles; conical intersections; nonadiabatic dynamics; photoisomerization; photoswitches.

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Figures

Figure 1
Figure 1
(top) Arylazopyrazoles studied in this work (R1=R2=H and R1=R2=CH3). Upon irradiation, both Z–E and E–Z photoisomerizations can occur. (bottom) Enantiomeric ground‐state cis minimum (left) and S1/S0 conical intersection (right) of Z11 with M helicity optimized at the CASSCF level (N=blue, C=gray, and H=white). Also shown is the atomic numbering. See the Supporting Information for plots of the enantiomeric species P‐Z11(S0) and P‐CI(S1S0) with P helicity and for Cartesian coordinates and relative energies.
Figure 2
Figure 2
Distribution of (top) the C2N3N4C5 dihedral angle and (bottom) the hopping times at all S1→S0 hopping points, with time‐dependent state populations and their time derivatives (insets). Left panels, trajectories starting from M‐Z11(S0); right panels, trajectories starting from P‐Z11(S0). Hops through M‐CI(S1S0) in blue, hops through P‐CI(S1S0) in red. See text for discussion.
Figure 3
Figure 3
Distribution of the C1C2N3N4 and C2N3N4C5 dihedral angles at the initial points (blue squares) and hopping points (red circles) of (left) Z11 and (right) Z8. Also shown are the percentages of hops through different S1/S0 conical intersection regions. See the Supporting Information for the distributions of other dihedral angles.
Figure 4
Figure 4
OM2/MRCI‐computed linearly interpolated internal coordinate (LIIC) paths (M‐M and M‐P) connecting the Franck–Condon point (M‐Z11(S0)) and the two S1/S0 conical intersections (M‐CI(S1S0) and P‐CI(S1S0)). Total OM2/MRCI energies are given for Z11 (left) and azobenzene (right). The LIIC paths are expected to approximate the intrinsic reaction coordinate (IRC) paths.
See this image and copyright information in PMC

References

    1. Szymański W., Beierle J. M., Kistemaker H. A. V., Velema W. A., Feringa B. L., Chem. Rev. 2013, 113, 6114–6178. - PubMed
    1. Velema W. A., Szymanski W., Feringa B. L., J. Am. Chem. Soc. 2014, 136, 2178–2191. - PubMed
    1. Beharry A. A., Woolley G. A., Chem. Soc. Rev. 2011, 40, 4422–4437. - PubMed
    1. Bandara H. M. D., Burdette S. C., Chem. Soc. Rev. 2012, 41, 1809–1825. - PubMed
    1. Woolley G. A., Acc. Chem. Res. 2005, 38, 486–493. - PubMed

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