Flexible Co(II)-and Ni(II)-Based Cationic 2D Metal–Organic Frameworks Based on a Charge-Neutral (O,O)-Donor Bridge
Round 1
Reviewer 1 Report
In the manuscript “Co(II)- and Ni(II)-based cationic 2D metal-organic frameworks 2 based on a charge-neutral (O,O)-donor bridge” Fedin et al synthesized two novel MOF materials with full characterization and CO2 adsorption experiment. The basic structure of the manuscript is good, and the material coordination chemistry has been explored very thoroughly. But I have some major issues regarding the characterization of MOFs.
1. The introduction is very and too general for me. Do not talk too much about the coordination behavior of MOF materials. See these references.
ACS Appl. Mater. Interfaces 2023, 15, 16, 20064–20074; Dalton Transactions, 2023, 52(14), 4501-4516; J. Mater. Chem. C, 2023, 11, 3692-3709.
2. You should transfer the PXRD pattern into the ESI.
3. In the CO2 adsorption experiments what about the pore size distribution? I don’t see any graph related to pore size distribution.
4. Can the author perform the N2 adsorption experiment? So that we can have a good comparison.
5. Compare the SCXRD data based on their cationic behavior to some literature reports.
6. What about the stability of such MOFs? Especially in the aqueous phase.
7. The UV-Vis analysis is too confusing for me. The author performed the solution-based UV or DRS. The DRS graph should be different in that case. Check carefully and write the description accordingly.
8. Also, improve the quality of English in the manuscript.
Overall improve the quality of English. There are some minor grammatical errors.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Demakov and co-authors report the synthesis and magnetic properties of two novel 2D coordination polymers with high flexibility. In my opinion, the work is interesting and the manuscript is very well written and presented. Some comments and suggestions for the authors:
- In Fig. 2B, the black square should be explained in the caption (I assume it represents the unit cell).
- The "short O..H contacts" (line 113) should be best reported as weak C-H...O hydrogen bonds and include the relevant angle, especially since the corresponding distance of 3.1 Å is well within the typical range of such a bond. G. R. Desiraju's work on the subject (for example, doi: 10.1039/b504372g) could also be included as a reference in this section.
- Line 125, "the coordination framework in 1 and 2 possesses 40 % total void volume, if erasing dioxane and perchlorate from the structure.". I think this part could be omitted, or rephrased, since the counteranions cannot be removed from the structure and thus this type of activation is impossible to achieve. The actual void volume is the one mentioned in the next sentence of the text (which only removes solvents).
- The reported activation protocol (exchange with THF once every two days) might be a little mild in order to have full solvent exchange. This could be a potential reason for the reported lower CO2 adsorption and pore volume values. I think it would be useful to include HNMR spectra of the framework (i) as-made, (ii) after THF exchange, (iii) after activation, to ensure the protocol is applied successfully.
- In Table 1, the notation "Vads (N2)" should read "Vads(CO2)".
- The authors report only adsorption studies for the polar CO2. It would be interesting to perform N2 adsorption studies on the frameworks, to determine further the flexibility of the system.
- The flexibility of the frameworks, in my opinion, could be investigated and explained in more detail. What is the driving force for this phenomena, and are they reversible? This could be observed through PXRD studies (e.g., over time, in an activated sample, after re-addition of solvent in the activated sample), or even single-crystal diffraction experiments, if the quality of the crystals is retained.
- Finally, since the authors mention their previous work with the same ligand system and transition metals, it would be interesting to include a comment on whether these structures also showed similar flexibility or magnetic behaviour.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The author has made considerable revisions. I am pleased to accept the manuscript in its current form.
