The singlet states of methyl cinnamate and methyl indenoate

Femtosecond S3→S1 Conversion and Structural Reorganisation of trans‐3‐Phenylprop‐2‐enaldehyde and Derivatives in Solution

“…As mentioned above, optical excitation occurs via the S 3 ! S 0 transition at 285 nm with an appreciable oscillator strength f = 0.34 in agreement with experiment [2] and with TD-DFT calculations. The transition to the lowest excited S 1 state is predicted to be very weak with f !…”

“…S 0 oscillator strength is approximately half that of the trans form, in agreement with earlier measurements. [1][2][3]10] Femtosecond transient absorption spectra are compared with calculations in Figure 9. The measured spectra (lines) are those of Figure 2 but the bleach contribution has been subtracted so that they now represent the sum of ESA and SE.…”

“…trans-3-Phenylprop-2-enaldehyde (cinnamaldehyde, 1 in Scheme 1) and many of its derivatives absorb in the UV spectral region and exhibit photoinduced cis-trans isomerisation [1][2][3][4][5] and dimerisation. [6][7][8][9][10][11] Both processes have been extensively characterised in solution and in crystals.…”

“…[5] Therefore the excited-state dynamics of cinnamic acid derivatives is essential for many applications and can be used as a model system for understanding the initial steps in the photocycles of the above-mentioned chromoproteins. Yet we are aware of only one time-resolved experiment with cinnamic acid derivatives; [2] a scarcity which may be explained since absorption and transient absorption of cinnamates occurs in the UV where ultrafast time-resolution is hard to achieve.…”

Photophysical properties and photochemistry of substituted cinnamates and cinnamic acids for UVB blocking: effect of hydroxy, nitro, and fluoro substitutions at ortho, meta, and para positions

“…Ishigami et al 23 reported the cistrans photoisomerization and relaxation of methyl cinnamate for some para-derivatives, but did not address the photostability. 24 In our previous studies, we investigated the photophysical properties of cis and trans isomers of the methoxysubstituted 2-ethylhexylcinnamates at various positions on an aromatic ring experimentally 25 and their model compounds theoretically. 26 Recently, we also theoretically studied the photophysical properties of the cinnamates and cinnamic acids with hydroxy, nitro, and fluoro substitutions using Density Functional Theory (DFT) and Time-Dependent DFT (TDDFT) calculations.…”