Trans,trans-1,4-diphenyl-1,3-butadiene

Study on the Photoisomerization Mechanism of Trans-, Trans-1,4-Diphenyl-1,3-Butadiene

Zheng, Xiaolei, et al. Physical Chemistry Chemical Physics, 2016, 18(13), 8971-8979.

This study utilized the SA2-CAS(4,4)/6-31G ab initio method along with an on-the-fly global-switching trajectory surface hopping algorithm to model the photoisomerization dynamics from the reactant trans, trans-1,4-diphenyl-1,3-butadiene (DPB) to the products cis,trans-DPB and cis,cis-DPB.
Key Findings
· Out of 600 sampled trajectories, 300 transitioned to the S0 state while 300 remained in the S1 state as resonances.
· The optimized CI1, which is involved in 295 of the non-resonance trajectories, emerges as the primary conical intersection influencing the photoisomerization of tt-DPB. In contrast, CI2, responsible for just 5 trajectories, has minimal impact.
· The simulated quantum yields for photoisomerization are φ_tt→ct = 0.090 and φ_tt→cc = 0.045, aligning well with experimental values of φ_tt→ct = 0.07-0.25 and φ_tt→cc = 0.02 observed in solution.
· Furthermore, this study estimates the decay lifetime from the S1 state of tt-DPB to be approximately 702.5 fs, with the lifetimes to products ct-DPB and cc-DPB being about 692.5 fs and 586.5 fs, respectively.