Peer review of: Complex k-uniform tilings by a simple bitopic precursor self-assembled on Ag(001) surface (2020)


RR2
Reviewers' comments:
Reviewer #2 (Remarks to the Author):
The authors have answered to the referees' comments in a proper way. Thus I will recommend publication as it is.
Reviewer #3 (Remarks to the Author):
The revised manuscript provides additional XPS and LEED results that give more insight into the self- assembly structures. The improvement is merited for acceptance.
Reviewer #4 (Remarks to the Author):
In the revised manuscript, the author studied the phases transformation of 3U to 2U to 1U through LEEM, which provides some new insights about the evolution of the tiling on surface. According to the definition of the k-uniform tiling by the authors based on the STM image, the similar k-uniform tiling has been found in the previous report (J. Am. Chem. Soc. 2013, 135, 7458-7461). Unfortunately, the internal transformation mechanisms between different phases cannot be well demonstrated by LEEM. Besides, the studies of well-known step-wise deprotonation (by XPS), which induced the evolution of hydrogen bonds, also can not improve the novelty of the manuscript. So, I still insist that the novelty of this manuscript does not meet the high standard of Nat. Commun. and I could not recommend its publication in this journal.
Reviewer #5 (Remarks to the Author):
I have looked through the paper and the previous exchanges between reviewers and authors. The paper is well written and provides a clear message about the observation of k-tilings. The novelty of the manuscript lies entirely with the classification of observed arrangements in terms of these tilings; as several referees have commented the the de-hydrogenation of carboxylic acids and the influence of this process on molecular ordering has been studied for many years and there is no intrinsic novelty of this aspect of the paper. So the question is whether the observation of this particular tessellation is enough to warrant publication in NC. I think I would support publication but the case is not overwhelming; in particular the recent ACS Nano Feng et al. mentioned by the authors is a very comprehensive piece of work which explores very similar ideas (although not the same particular arrangements).
However I had some other comments:
1. tessellations imply ordering over reasonably long length scales. The images shown in the main text are very small and could be due to localised domains rather than extended order. The authors should

include larger images, preferably in the main paper, but in the SI if that is preferred, to show the molecular ordering on a scale which is comparable to the current Fig S8.
2. The ACS Nano paper mentioned by the authors in their response should be cited.
3. I didn't understand the arguments related to the domain boundaries in Fig S8 - top of page 12 - dissolving of phases. Also there seemed to be regions of 4U (?) in Fig. S8 - do these extend over large areas.
4. In my view the LEEM images looked very interesting - I haven't seen this kind of data used to investigate the evolution of these phases previously. It seemed to be a shame not to highlight it more prominently.