Average rating: | Rated 4.5 of 5. |
Level of importance: | Rated 5 of 5. |
Level of validity: | Rated 4 of 5. |
Level of completeness: | Rated 5 of 5. |
Level of comprehensibility: | Rated 4 of 5. |
Competing interests: | None |
The publication presents simulations of the smallest currently known chiral photoswitches, including extensive comparisons to non-chiral parent compounds, to which some of the methods have been previously parametrized and validated. The text is well written and can usually be understood without reading the previous work, although reference to that previous work is made rather frequently.
There are a few places where the self-contained character could be improved. In particular, Table 5 could make more explicit that the new results are all computational (repeat the level in the caption) and gas phase, because not all of the table entries are. The gas phase character of the simulations could also be made more explicit early on in the publication (earlier than page 6).
This also touches one of the topics where the manuscript is hardest to digest, the influence of the solvent. In the parent compound there was a large solvent effect in the computations and only the solvent calculation came close to experiment. In the new compounds, where experimental values and solvent computations are unknown, the computed gas phase quantum yields do deviate from those of the parent compound and move in the direction of its solvent effect. This might be coincidental, but in the conclusions it is speculated that it may also be due to a solvent-like influence of the added ring frames. However, solvent-including simulations supporting this hypothesis are not presented for the new compounds.
In the comparison of MP2 and AM1 calculations, some readers may be curious to learn about the computational speed-up involved in the AM1 approach. Also, the effect of quantum decoherence correction could be exemplified for one of the systems, as this is speculated to be one of the (smaller) reasons for deviations in the reference system.
Overall, the manuscript nicely sets the stage for future calculations of molecular machines exploiting this chromophore (ref. 10), and of course also for future photoswitching experiments using these chiral molecules. It definitely confirms the design of these photoswitches to be unidirectional and is therefore important.