1-8-2022 First revision
Journal: New Journal of Chemistry
Manuscript number: NJ-ART-12-2021-006042
MS Type: Article
Title: "Metal-organic framework based on flexible ligands and CoII-CoII-CoII system: selective gas adsorption and magnetic properties"
Correspondence Author: Prof. Dr. Chuanlei Zhang
E-mail: clzhang@nju.edu.cn
Dear Professor Junk,
Firstly, thank you for your kind letter and for reviewers’ constructive comments concerning our article (Manuscript No.: NJ-ART-12-2021-006042). These comments are all valuable and helpful for improving our article. All the authors have seriously discussed about all these comments. According to the reviewers’ comments, we have tried best to modify our manuscript to meet with the requirements of your journal. In this revised version, changes to our manuscript within the document were highlighted by using yellow colored text. Point-by-point responses to the reviewers are listed below this letter. (Q: Question; A: Answer)
Thank you very much for your kind consideration.
Best wishes,
Sincerely yours,
Chuanlei Zhang
=====================================
Q1:The manuscript should be polished up in English grammar, include some non-idiomatic English and misspellings.
A: Thanks for your nice suggestion! After careful consideration, we have removed the inappropriate grammar and wrong spelling.
Q2: Is there an inevitable correlation between linear tri-nuclear CoII-CoII-CoII system and weak ferromagnetism interaction in this MOF? Please provide a rational explanation.
A: Thanks for your question! Linear tri-nuclear CoII-CoII-CoII system has a certain relationship with weak ferromagnetism. This is due to the integration of multiple metal ions in the system, resulting in a cumulative effect that allows it to respond more strongly to changes in the magnetic field and exhibit a weaker ferromagnetic signal.
Q3: The author does not give a more comprehensive comparison of the selective adsorption of other gases, such as ethylene, H2 and so on.
A: Thanks for your suggestion! We are mainly providing a new and bright pathway to global climate issues by using the selective adsorption of CO2 by flexible MOF. Therefore, we do not carry out adsorption tests for other gases, such as ethylene, H2 and so on.
Q4: Does the change of temperature and flexibility of the MOF have a great impact on the adsorption capacity of CO2?
A: Thanks for your question! The adsorption capacity of CO2 is negatively correlated with temperature. The MOF's capability to adsorb CO2 decreases when the temperature increases. The volume of CO2 adsorption by a rigid framework is stationary, whereas the morphology of the pore and framework will undergo changes after the adsorption of CO2 takes place in a flexible framework, which can have an effect on the capacity of the flexible MOF to adsorb CO2, such as the breathing behavior of MIL-53(Al) (J. Colloid Interf. Sci., 2015, 447, 33-39).
Q5: In Fig. 6 and 7a, why is the thermal stability so high (up to 350 °C) in the case of flexible framework?
A: Thanks for your question! Flexible frameworks have a certain degree of freedom in terms of spatial extension. Within a certain range of temperature, the coordination bonds is not broken, so the weight loss curve of MOF tends to remain unchanged.
===============The end of the response to Referee 1 ===============
Referee: 2
Q1:The MOF is formulated as {[Co3(TCBA)2·BMB]·2DMF·6H2O}n, how did the authors calculate the chemical stoichiometric coefficients of DMF and H2O molecules in the chemical formula?
A: Thanks for your question! We calculate the chemical stoichiometric coefficients of DMF and H2O molecules by thermogravimetric analysis and single-crystal structure analysis.
Q2: The collapse of framework at over 350 °C leads to the exposure of open metal sites, which are suitable for a catalytic reaction with respect to CO2?
A: Thanks for your question! This article focuses on the synthesis of flexible ligands for the construction of flexible MOFs and their application for selective gas adsorption, and we have not considered the effect of the exposure of open metal sites on CO2 conversion. In the next experimental investigations, we will dig deeper into this direction.
Q3: In Fig.4, the author does not give a comparison of CO2 adsorption capacity of two topologies under the same conditions.
A: Thanks for your question! We have not synthesized a framework with the topology flu-3,6-C2/c. We have mainly focused on this framework (with point symbol of {42·6}2{44·62·87·102}) as a basis to help the reader understand our new topology with the point symbol of {42·6}2{44·610·79·85}. Therefore, we did not perform CO2 adsorption tests on this classical topology.
Q4: Compared to flexible MOF, the paper does not show experiments on selective gas adsorption of rigid frameworks.
A: Thanks for your question! The highlight of this paper is the design and synthesis of flexible ligands for the construction of linear tri-nuclear Co(II)-MOF, and the selective adsorption of CO2 by flexible MOFs. Consequently, we have not considered the synthesis of rigid frameworks and the testing of their capability of selective gas adsorption.
=============== The end of the response to Referee 2 ===============
Referee: 3
Q1:There is 1 (CCDC 1840305) Structure in this paper. We examined this file: 1840305. The mean I/σ(I) is only 5.9 -- and Rint is 12.88%. The minimum required resolution of 50° in 2θ has not been reached I/σ(I) is only 1.3 at that point!). On top of this, there is something really strange with the Fobs vs Fcalc plot -- and tall R values are high. There is no note regarding any of this in the CIF.
A: Thanks for your nice suggestion! Due to the quality of the crystal itself, the signal-to-noise ratio is not very high (1.3) and the Rint is a little big (0.1288). We failed to get a very high-quality single crystal by continuously optimizing the crystallization conditions for nearly one year. However, this does not affect its structural determination, because the thermal displacement of each atom in the structure is very small, the bond length and bond angle between atoms are within a reasonable range, and Alert A and B have been solved.
Q2:There is also something very strange going on with the solvent mask: it looks like the embedded hkl file has already been masked, and the also embedded fab file is empty. What exactly is going on here? There is a huge void, but there is no density in it at all? Also, the embedded hkl file is merged.
A: We are very sorry for this problem with the structure. We have refined the original data through the latest software (including Shelxtl, Platon) and obtained the updated structure. The problem you raised have been solved. Thank you again for your correction.
Q3:Please update your structure, making sure that the original, full, un-merged and un-masked hkl file as well as the fab file (resulting from the latest version of your masking software) will be included in the CIF file. You must also report the number and nature of the masked entities in your moiety and sum formulae.
A: Thanks for your suggestion! We have updated the original, full, un-merged and un-masked hkl file as well as the fab file in the CIF file. The number and nature of masked entities in this moiety is two DMF and six water molecules, which are all merged to the sum formulae, formed as {[Co3(TCBA)2·BMB]·2DMF·6H2O}n. These are reflected and explained in the description of crystal structure in the text.
Q4:Please make sure that your new files will reach the minimum resolution of 50° in 2θ (i.e. the mean I/σ(I)I at that point should be > 3).
A: Thanks for your suggestion! After re analyzing the crystal structure, the mean I reaches 7.08 at the resolution of 50° in 2θ, and the mean I/σ(I) at that point reaches 3.95.
Q5:Please use CheckCif as a guide in the final preparation of these structures. There should be no CheckCif A or B alerts remaining, and if any of them do, you must provide relevant and meaningful vrf entries.
A: Thanks for your suggestion! We have solved all alerts A and B in the new files.
=============== The end of the response to Referee 3 ===============
1-12-2022 Second revision
Journal: New Journal of Chemistry
Manuscript number: NJ-ART-12-2021-006042
MS Type: Article
Title: "Metal-organic framework based on flexible ligands and CoII-CoII-CoII system: selective gas adsorption and magnetic properties"
Correspondence Author: Prof. Dr. Chuanlei Zhang
E-mail: clzhang@nju.edu.cn
Dear Professor Junk,
Thank you for giving us this opportunity to continue to revise the manuscript (No.: NJ-ART-12-2021-006042). The questions raised by reviewer 3 will be treated with caution again. After consulting professionals, we update the modified CIF file to the CCDC database this time. Please see the screenshot below. The software used in our refinement is xl 2018, and the Platon software used to filter the solvent is updated to the latest version of 2021.2. The problem of the solvent mask mentioned by reviewer has been explained in the description of crystal structure in the text, which is due to the use of PLATON SQUEEZE algorithm. The filtered solvents have been determined by thermogravimetry and calculated electron density, and incorporated into the molecular formula. This treatment and description are consistent with other literature (J. Am. Chem. Soc. 2011, 133, 1634–1637; Chem. Sci., 2021, 12, 13793–13801, etc). During the refinement process, the ABIN instruction has been added to the ins file, otherwise the desired results will not be obtained. We asked professionals to help complete the single crystal test and refinement (State Key Laboratory of Coordination Chemistry, Nanjing University).
In this revised version, changes to our manuscript within the document were highlighted by using yellow colored text. Point-by-point responses to the reviewers are listed below this letter. (Q: Question; A: Answer)
Thank you very much for your kind consideration.
Best wishes,
Sincerely yours,
Chuanlei Zhang
=====================================
Q1:I appreciate that it is sometimes very hard to obtain good crystals. It is, therefore, all the more important that the crystals that *can* be obtained should be measured to the highest possible standard.
A: We really agree with your suggestion. During the test, we try our best to debug the test parameters, such as exposure time, scan width, etc., based on the accurate determination of the crystal structure. All index, especially the data completeness, R (reflections), wR2 (reflections), goodness, shift/su_max, largest diff. peak and hole, etc., meet the requirements of the journal. In most cases, our resolution and structure factor are in a very reasonable range, refer to our previous articles (Chemical Communications, 2015, 51: 8338-8341; Chemistry-A European Journal, 2018, 24: 327-331; Dalton Transactions, 2019, 48(7): 2285-2289, etc). However, there are also exceptions, the quality of crystal data can not meet the requirements of special crystal journals such as crystal journal, and the test conditions have reached the limit on the existing instruments. This is a fact that we must admit and account for. Thank you very much for your professional and sincere advice.
Q2: What was the exposure time for this data collection, and what was the scan width? Please answer this question.
A: According to negotiation with the tester for many times, without affecting the tests of other research groups, we used afternoon and evening to test better data, and the exposure time was 12 seconds and the scan width was 0.5 degree.
Q3: Technically, the required resolution of 50° in 2Θ has not been reached -- if this is simply due to an inadequate experimental setup, then this is quite different to from this being due to the poor quality of the crystal alone.
A: Thank you for your professional question. In order to obtain higher-quality data, the testers have given the maximum inclination to the instrument settings. Frankly speaking, this is indeed an irreparable shortcoming.
Q4: As for the solvent mask: the embedded hkl file is still not the original, un-masked file. When I apply a mask to this file, then this mask will find a large void (704 Å^3) with no electron density at all. This is simply not possible if the embedded hkl file is not masked. Please go back to your original frames and re-integrate your frames. If you wish to apply a mask, please use a modern masking program, making sure that the original hkl will be embedded as well as the fab file. Your ins file must contain the ABIN instruction if you have done everything as it should be. I would really like to help here, but in the absence of the original hkl there is nothing I can do.
A: We are very sorry that this problem bothers you, because we did not explain it clearly. The solvent mask is due to the use of PLATON SQUEEZE algorithm. The filtered solvents have been determined by thermogravimetry and calculated electron density, and incorporated into the molecular formula. During the refinement process, the ABIN instruction has been added to the ins file. The platon software used to mask solvent is updated to the latest version of 2021.2, and the original hkl and fab file have be embedded in the cif file.
Q5: I am very confused now, since you state "We have updated the original, full, un-merged and un-masked hkl file as well as the fab file in the CIF file" -- but this is clearly not true -- at least not with the files I obtained today, on 11/1/22. But then, the deposition with the CCDC is dated 07 December 2021 -- i.e. from before my last review.
A: Very sad apology, we didn't fully understand what you meant last time. We think that we can answer your question by reparsing the structure and packaging and uploading all the new structures without A/B alerts. This time, we did upload the revised CIF file on the CCDC website to replace the previous file. The file has no A/B alerts, and the data quality has been relatively improved.
=============== The end of the response to Referee 3 ===============
1-15-2022 Third revision
Journal: New Journal of Chemistry
Manuscript number: NJ-ART-12-2021-006042
MS Type: Article
Title: "Metal-organic framework based on flexible ligands and CoII-CoII-CoII system: selective gas adsorption and magnetic properties"
Correspondence Author: Prof. Dr. Chuanlei Zhang
E-mail: clzhang@nju.edu.cn
Dear Professor Junk,
Thank you very much for the good news about this manuscript. The very professional comments and solutions given by reviewer 3 are very admirable. According to the reviewer’s comments, we adopted the results of the reviewer's refinement of the structure, and all the contents involved in the text were corrected and highlighted. In addition, we update the modified CIF file to the CCDC database again.
Thank you very much for your kind consideration.
Best wishes,
Sincerely yours,
Chuanlei Zhang
=====================================
Our letter of thanks to the Xray reviewer
Dear Professor,
Thank you very much for your decision and practical help. We fully accept your treatment of the structure and apply the results to the corresponding parts of the manuscript. After solving two A alerts, we update the modified CIF file to the CCDC database again.
We all appreciate your professionalism, patience and meticulosity. Your help to us is also to the journal and all readers. You have shown us a rigorous academic creation process and a responsible scholar attitude. I will put the review process of this paper on our personal home page (https://www.x-mol.com/groups/clzhang?lang=en) for more people to learn this rigorous and realistic scientific spirit.
Best wishes,
Sincerely yours,
Chuanlei Zhang
=============== The end of the response to Referee 3 ===============