A novel sodium-fluorescent crystal

In this work, a novel sodium-fluorescent crystal (Na-FS) was synthesized from 4-dimethylaminobenzoic acid and sodium hydroxide by one-pot hydrothermal method. The structure and conformation of Na-FS were confirmed by single-crystal X-ray diffraction and scanning electron microscope, and the optical properties were studied by fluorescence spectrometer. The results showed that: Na-FS was a triclinic crystal, space group was P-1, cell parameters a, b and c were 10.5113(3), 15.9198(5) and 15.9560(5) Å, respectively, and the number of independent atoms Z in a structure cell was two. Additionally, Na-FS has a blue fluorescence emission (around 360 nm under excited at the range of 230–300 nm) with great photostability and photobleaching resistance, and the quantum yield of Na-FS is 30.58%.


4.
In figure 4, please add the spectra of the ingredients of Na-FS to exclude the possibility that the fluorescence of Na-FS might come from one of its ingredients. 5.
It will be better if the authors could find some practical application for these crystal materials. 6.
Some typos need to be revised. I will only list some but not all. Page 4, line 15, " intramololular" should be "intramolecular"; Page 9, line 25, "rihgt" should be "right".
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Dear Dr Ma:
Title: A Novel Sodium-Fluorescent Crystal Manuscript ID: RSOS-201987 Thank you for submitting the above manuscript to Royal Society Open Science. On behalf of the Editors and the Royal Society of Chemistry, I am pleased to inform you that your manuscript will be accepted for publication in Royal Society Open Science subject to minor revision in accordance with the referee suggestions. Please find the reviewers' comments at the end of this email.
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Supplementary files will be published alongside the paper on the journal website and posted on the online figshare repository (https://figshare.com). The heading and legend provided for each supplementary file during the submission process will be used to create the figshare page, so please ensure these are accurate and informative so that your files can be found in searches. Files on figshare will be made available approximately one week before the accompanying article so that the supplementary material can be attributed a unique DOI. ********************************************** RSC Associate Editor: Comments to the Author: (There are no comments.) RSC Subject Editor: Comments to the Author: (There are no comments.) ********************************************** Reviewer comments to Author: Reviewer: 1 Comments to the Author(s) This is a quite straightforward study to synthesize a sodium-fluorescent crystal by a hydrothermal method. The crystal structure was measured by XRD, and the morphology was evaluated by SEM. The blue fluorescence was stable and resistant to photobleaching. I have a few suggestions for the authors below: 1. For the morphology evaluation, only SEM was used. More material characterization is suggested, for example, TEM, DLS etc. 2. How stable is Na-FS in the aqueous solution? 3. Why is Na-FS unique as a fluorescent material? Will it be more suitable for any particular applications? For example, cell labeling (imaging)? 4. What is the quantum yield for the fluorescence of Na-FS, e.g. excited by 290nm UV?
Reviewer: 2 Comments to the Author(s) This paper reported a new sodium crystal that possesses unique fluorescent properties. The crystal was fully characterized, and its structure was interpreted. Overall, the paper is in decent shape. The experiments were well designed, and the results could support its hypothesis to some extent. I am very pleased to recommend its publication if the following questions could be properly addressed. 1. The authors claimed it is a "novel" sodium-fluorescent crystal. Did the authors do intensive enough research work to draw this conclusion? If it was the so-called "novel" one, the authors need to provide more details about its structure, say, the standard XRD peaks profile of this crystal. And it is also the obligation to name it, so future researchers can reproduce it if it is necessary to do so. 2. In figure 2, the authors used SRD to interpret the structure of the crystal. It is one of the most pivotal pieces of information to prove that the product is a real crystal. But the authors failed to reveal the information of one cell lattice. If the authors can provide that information in the manuscript, it will help the authors to understand the structure of the crystal better. 3. In figure 3, the authors employed TG to characterize the crystal, however, they did not fully interpret the data they got and failed to draw any conclusions based on the TG findings. Please revised that part in the manuscript accordingly. 4. In figure 4, please add the spectra of the ingredients of Na-FS to exclude the possibility that the fluorescence of Na-FS might come from one of its ingredients. 5. It will be better if the authors could find some practical application for these crystal materials. 6. Some typos need to be revised. I will only list some but not all. Page 4, line 15, " intramololular" should be "intramolecular"; Page 9, line 25, "rihgt" should be "right".

Decision letter (RSOS-201987.R1)
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Please see the Royal Society Publishing guidance on how you may share your accepted author manuscript at https://royalsociety.org/journals/ethics-policies/media-embargo/. After publication, some additional ways to effectively promote your article can also be found here https://royalsociety.org/blog/2020/07/promoting-your-latest-paper-and-tracking-yourresults/. Answer: To answer this question, the stability of Na-FS fluorescence intensity in natural placement was studied. As shown in Fig.S2, the fluorescence intensity stay a steady value in 4 days. The fluorescence stability can prove Na-FS is a stable material in the aqueous solution. (Page S1 of supporting information). Answer: The quantum yield of Na-FS is 30.58 % (when excited at 290nm). This part has been added in page 11 according to reviewer's kindly comments. The method detail Appendix A was provided in supporting information page S2.

Reviewer: 2
Comments to the Author(s) This paper reported a new sodium crystal that possesses unique fluorescent properties. The crystal was fully characterized, and its structure was interpreted. Overall, the paper is in decent shape. The experiments were well designed, and the results could support its hypothesis to some extent. I am very pleased to recommend its publication if the following questions could be properly addressed.
1. The authors claimed it is a "novel" sodium-fluorescent crystal. Did the authors do intensive enough research work to draw this conclusion? If it was the so-called "novel" one, the authors need to provide more details about its structure, say, the standard XRD peaks profile of this crystal.
And it is also the obligation to name it, so future researchers can reproduce it if it is necessary to do so.
Answer: The PXRD (powder X-ray diffraction) pattern of Na-FS was showed in Fig.1,   2θ of Na-FS are 12°, 20° and 26°, which had no standard XRD spectra in databases. 2. In figure 2, the authors used SRD to interpret the structure of the crystal. It is one of the most pivotal pieces of information to prove that the product is a real crystal. But the authors failed to reveal the information of one cell lattice. If the authors can provide that information in the manuscript, it will help the authors to understand the structure of the crystal better.
Answer: The cell parameters a, b and c of Na-FS was 10.5113(3), 15. 9198(5), and 15.9560(5) Å, and the data has been displayed in 3. In figure 3, the authors employed TG to characterize the crystal, however, they did not fully interpret the data they got and failed to draw any conclusions based on the TG findings. Please revised that part in the manuscript accordingly.
Answer: TG characterization has been revised according to reviewer's recommendation.
As shown in Fig.4, a weight loss about 30% of Na-FS was observed in the first stage of TG curve (the temperature region from 100 °C to 140 °C), which was due to the loss of