Facile Fabrication of Glycosylpyridyl-Triazole@Nickel Nanoparticles as Recyclable Nanocatalyst for Acylation of Amines in Water
Round 1
Reviewer 1 Report
1. There are no explanations of the abbreviations used in the paper, e.g. DMA, DMP, DMF, XPS.
2. There is no description of the measurement procedures and information about the apparatus used for characterisation of glycosylpyridyl-triazole@nickel nano catalysts (GPT-Ni).
3. The authors boast about their success: obtaining novel glycosylpyridyl-triazole@nickel nanoparticles (GPT-Ni), so why did they present and discuss the obtained results concerning the characterisation of the new catalyst so superficially? Figure 2 is too small and completely illegible after printing. I found only one reference to “Supporting Information” in the sentence “When the reaction of NiCl2 (1.0 61 equiv.) and glycosyl pyridyl-triazole (1.2 equiv.) was set up, a GPT-Ni formulated as dimer was obtained as the sole product, which was characterized by HRMS, EA and IR (see ESI†, Fig S1-3) (60-62)”, but there is no discussion whatsoever about what these results tell us about the quality of the obtained nano catalyst.
4. I was very surprised by the sentence: “The elemental composition of the catalyst was determined by XPS (69)” without any reference to the location of the results. I found the results of the analysis in “Supporting Information” in Figure S2, but there is no information about the quantitative content of individual elements. The composition of the nano catalyst based on Figure S2 can be assessed only roughly.
5. There is no explanation of why silicon (Figure S2) is one of the main components of the nano catalyst, given that it was not used as a reagent for the synthesis.
6. I think that the XRD results should be provided for a wider range of 2-Theta angle. XRD data should be presented legibly, not as a drawing of overlapping peaks.
7. The TEM image (Figure 2d) should be presented in the form of a separate large drawing. Based on TEM the authors should make a distribution of size of the obtained sample.
General remark: The authors boast about obtaining a new nano catalyst, so the obtained results should be presented in a reliable manner, which will allow this “paper” to receive the status of a reference (often cited) paper regarding this nano catalyst. At present, the manuscript requires many corrections before it can be published.
Author Response
Referee 1:
Comment: General remark: The authors boast about obtaining a new nano catalyst, so the obtained results should be presented in a reliable manner, which will allow this “paper” to receive the status of a reference (often cited) paper regarding this nano catalyst. At present, the manuscript requires many corrections before it can be published.
Response: We thank the reviewer for the positive comments. We have carefully reviewed the comments and made changes to the manuscript in blue according to the suggestions.
Comment 1) There are no explanations of the abbreviations used in the paper, e.g. DMA, DMP, DMF, XPS.
Response: The DMA, DMP, DMF, XPS, EA have been explained in manuscript.
Comment 2) There is no description of the measurement procedures and information about the apparatus used for characterisation of glycosylpyridyl-triazole@nickel nano catalysts (GPT-Ni).
Response: We thank the reviewer for the comments. The description of the measurement procedures and information about the apparatus have been added in experimental materials in manuscript.
Comment 3) The authors boast about their success: obtaining novel glycosylpyridyl- triazole@nickel nanoparticles (GPT-Ni), so why did they present and discuss the obtained results concerning the characterisation of the new catalyst so superficially? Figure 2 is too small and completely illegible after printing. I found only one reference to “Supporting Information” in the sentence “When the reaction of NiCl2 (1.0 61 equiv.) and glycosyl pyridyl-triazole (1.2 equiv.) was set up, a GPT-Ni formulated as dimer was obtained as the sole product, which was characterized by HRMS, EA and IR (see ESI†, Fig S1-3) (60-62)”, but there is no discussion whatsoever about what these results tell us about the quality of the obtained nano catalyst.
Response: We thank the reviewer for the constructive comments. Figure 2 has been revised and The GPT-Ni nanocatalyst was characterized by X-ray photoelectron spectrographs (XPS), high resolution mass spectrum (HRMS), X-ray diffraction (XRD), thermogravimetric analysis (TG) and transmission electron microscopy (TEM). Following some similar references (Green Chem., 2015, 17, 2251-230. Catal. Sci. Technol., 2015, 5, 2065-2071), when the reaction of NiCl2 and glycosyl pyridyl-triazole was set up, a nano-size GPT-Ni particles as dimer was obtained as the sole product and the nano catalyst was characterized by TEM.
I was very surprised by the sentence: “The elemental composition of the catalyst was determined by XPS (69)” without any reference to the location of the results. I found the results of the analysis in “Supporting Information” in Figure S2, but there is no information about the quantitative content of individual elements. The composition of the nano catalyst based on Figure S2 can be assessed only roughly.
Response: We thank the reviewer for the comments. ‘The elemental composition of the catalyst’was changed to ‘The characteristic value of the catalyst’. There's something wrong with the data and the results of the analysis in “Supporting Information” in Figure S2 has been deleted.
There is no explanation of why silicon (Figure S2) is one of the main components of the nano catalyst, given that it was not used as a reagent for the synthesis.
Response: We thank the reviewer for the comments. There's something wrong with the data and the Figure S2 has been deleted.
I think that the XRD results should be provided for a wider range of 2-Theta angle. XRD data should be presented legibly, not as a drawing of overlapping peaks.
Response: The XRD data was marked with different colours and the characteristic peaks were shown clearly.
The TEM image (Figure 2d) should be presented in the form of a separate large drawing. Based on TEM the authors should make a distribution of size of the obtained sample.
Response: We thank the reviewer for the comments. The TEM image in Figure 2d has been revised and it looks clearer then before.
Reviewer 2 Report
The present paper describes the successful heterogenization of the acylation reaction of amines by catalysis with Ni complexes using previously described glycosylpyridyl-triazole ligands, in the solid state. The authors describe the positive effect of sodium L-ascorbate as a reducing agent and water as solvent in the catalytic reaction. The results are interesting and, in my opinion, the paper can be published after the manuscript is revised in accordance with the following notes and the following questions have been answered:
Which was the solvent used to obtain ESI-MS spectra (line 62)? The nanoparticles dissolved in this solvent to afford the individual complexes? This should be clarified in the paper.
The authors should give an explanation for obtaining nano-size particles (observed by TEM) by simple precipitation of the complexes.
It is important to provide the survey spectra and the atomic percentages values calculated.
Elemental analysis on Figure S3 was obtained by XPS? This should be specified.
It is useful to describe the peak at near 860 eV in the XPS high resolution spectra of Ni as a satellite of the 2p3/2 peak.
The description of the apparatus and conditions used to perform TEM and XPS analyses should be provided in the experimental.
The experimental data is repeated in the paper and in ESI.
Some reference to the IR results should be provide in the paper as they certify the chemical structure of the catalyst, not obtained by the other techniques.
Line 76/77, “we characterize the surface morphology and crystal structure of the synthesized catalysts by TEM”. Please remove the strikethrough words. Wide the size range of the particles as the image has a low resolution.
Line 79, please give a more objective description of the dispersion of catalyst particles instead of “dispersion of Ni particles were very well”. This are not Ni particle, this should be replaced by catalyst particles. “TEM image” not “images” (also in the legend of Figure 2).
In the recycling experiments, no mass loss of catalyst was observed?
Schemes 3a and 3b referred in lines 141 and 144, respectively, are not shown and should be.
Line 33/34, which is the advantage of decreasing catalyst stability?
How the products were identified and quantified in the recovery experiments, they were dryed? This should be clarified in the paper.
Minor:
Carefully describe the abbreviations in the first time they are presented in the text, namely DMA and DMP should not be used in the abstract without description as they can have other meanings.
By coherence Figure 1 should be Scheme 2. Show it after being referred in the text.
The use of sodium L-ascorbate is preferred instead of VC Na or provide a convenient description of this abbreviation the first time is used in line 97.
Other missing abbreviations are EA line 178
Line 185, what ether was used.
Legend of Table 2, compounds numbers in bold.
Line 45, square brackets are missing for reference 34.
Author Response
Referee 2:
Comment The present paper describes the successful heterogenization of the acylation reaction of amines by catalysis with Ni complexes using previously described glycosylpyridyl-triazole ligands, in the solid state. The authors describe the positive effect of sodium L-ascorbate as a reducing agent and water as solvent in the catalytic reaction. The results are interesting and, in my opinion, the paper can be published after the manuscript is revised in accordance with the following notes and the following questions have been answered:
Response: We thank the reviewer for the positive comments.
Comment 1) Which was the solvent used to obtain ESI-MS spectra (line 62)? The nanoparticles dissolved in this solvent to afford the individual complexes? This should be clarified in the paper.
Response: We thank the reviewer for the comments. The GPT-Ni nanocatalyst was synthesized using a convenient approach by reacting nickel chloride with glycosyl pyridyl-triazole as ligands using tetrahydrofuran (THF) as solvent. It has been clarified in manuscript.
Comment 2) The authors should give an explanation for obtaining nano-size particles (observed by TEM) by simple precipitation of the complexes.
Response: We thank the reviewer for the comments. Following some similar references(Green Chem., 2015, 17, 2251-230. Catal. Sci. Technol., 2015, 5, 2065-2071), when the reaction of NiCl2 and glycosyl pyridyl-triazole was set up, a nano-size GPT-Ni particles as dimer was obtained as the sole product, which was characterized by TEM.
Comment 3) It is important to provide the survey spectra and the atomic percentages values calculated. Elemental analysis on Figure S2was obtained by XPS? This should be specified.
Response: The elemental analysis on Figure S2 was obtained by XPS, but there's something wrong with the data and the Figure S2 has been deleted.
Comment 4) It is useful to describe the peak at near 860 eV in the XPS high resolution spectra of Ni as a satellite of the 2p3/2 peak.
Response: We thank the reviewer for the constructive comments. The Ni (2p3/2) and Ni (2p1/2) peaks were observed at 854.98 and 872.38 eV, respectively, which are the characteristic values of the Ni2+ (ChemSusChem., 2019, 12, 1246-1255). Most of the nickel nanoparticles were present in their oxidized state as detected by XPS, which revealed that the metallic nickel on the surface of nickel nanoparticles was majorly oxidized into its oxidized state eitherby the air during the storage.
Comment 5) The description of the apparatus and conditions used to perform TEM and XPS analyses should be provided in the experimental.
Response: We thank the reviewer for the constructive comments. The description of the apparatus and conditions used to perform TEM, XRD and XPS analyses have been provided in the experimental.
Comment 6) The experimental data is repeated in the paper and in ESI.
Response: We thank the reviewer for the comments. The repeat experimental data has been deleted in ESI.
Comment 7) Some reference to the IR results should be provide in the paper as they certify the chemical structure of the catalyst, not obtained by the other techniques.
Response: We thank the reviewer for comments. Some references to the IR results have been provide in the paper.
Comment 8) Line 76/77, “we characterize the surface morphology and crystal structure of the synthesized catalysts by TEM”. Please remove the strikethrough words. Wide the size range of the particles as the image has a low resolution.
Response: We thank the reviewer for the comments. The strikethrough words have been deleted and the image has been revised.
Comment 9) Line 79, please give a more objective description of the dispersion of catalyst particles instead of “dispersion of Ni particles were very well”. This are not Ni particle, this should be replaced by catalyst particles. “TEM image” not “images” (also in the legend of Figure 2).
Response: We thank the reviewer for the comments. The ‘Ni particles’ was changed to ‘catalyst particles’ and ‘TEM iimages’ was changed to “TEM image”.
Comment 10) In the recycling experiments, no mass loss of catalyst was observed?
Response: When the reaction was completed, the catalyst was recovered by filtration and washed with water and ether. After drying, the retrieved catalyst was weighted and reused, almost no mass loss of catalyst was observed.
Comment 11) Schemes 3a and 3b referred in lines 141 and 144, respectively, are not shown and should be.
Response: We thank the reviewer for the comments. The Scheme 3 Mechanism study. has been added in manuscript.
Comment 12) Line 33/34, which is the advantage of decreasing catalyst stability?
Response: We thank the reviewer for the comments and ‘decreasing catalyst stability’ was changed to ‘improving catalyst stability’.
Comment 13) How the products were identified and quantified in the recovery experiments, they were dryed? This should be clarified in the paper.
Response: Yes, the products were dryed and quantified which have been clarified in the paper.
Comment 14) Minor: Carefully describe the abbreviations in the first time they are presented in the text, namely DMA and DMP should not be used in the abstract without description as they can have other meanings.
Response: We thank the reviewer for the comments. The N,N-dimethylacetamide (DMA), N,N-dimethylpropionamide (DMP) and N,N-dimethylformamide (DMF) have been revised in the abstract.
Comment 15) By coherence Figure 1 should be Scheme 2. Show it after being referred in the text.
Response: We thank the reviewer for the comments. ‘Figure 1’ was changed to ‘Scheme 2’
Comment 16) The use of sodium L-ascorbate is preferred instead of VC Na or provide a convenient description of this abbreviation the first time is used in line 97.
Response: ‘VC Na’ was changed to ‘sodium L-ascorbate’ which is used as reductant and it has been revised in manuscript.
Comment 17) Other missing abbreviations are EA line 178
Response: ‘EA’ in line 178 was changed to ‘ethyl acetate’
Comment 18) Line 185, what ether was used.
Response: Ether was used as washing solvent.
Comment 19) Legend of Table 2, compounds numbers in bold.
Response: The compounds numbers are in bold in legend of Table 2.
Comment 20) Line 45, square brackets are missing for reference 34
Response: We thank the reviewer for the comments. The square brackets have been added for reference 34
Reviewer 3 Report
The authors reported Ni nanoparticle catalyst for acylation of amines. The prepared Ni catalysts were well characterized by several spectroscopic techniques, such as TEM and XRD. The catalyst showed high activity, selectivity, and wide scope of substrate. In addition, the excellent reusability indicates practical usefulness of the catalyst system. The paper is publishable in the journal after minor revisions. The comments are as follows:
1) What is “VC Na”?
2) If possible, please add the data of XPS spectrum of reduced (used) Ni catalyst (Ni(0)).
3) Please show a reaction results for only reductant (without Ni catalyst) as a control.
Author Response
Referee 3:
Comment:The authors reported Ni nanoparticle catalyst for acylation of amines. The prepared Ni catalysts were well characterized by several spectroscopic techniques, such as TEM and XRD. The catalyst showed high activity, selectivity, and wide scope of substrate. In addition, the excellent reusability indicates practical usefulness of the catalyst system. The paper is publishable in the journal after minor revisions. The comments are as follows:
Response: We thank the reviewer for the positive comments. We have carefully reviewed the comments and made changes to the manuscript in blue according to the suggestions.
Comment 1) What is “VC Na”?
Response: ‘VC Na’ is ‘sodium L-ascorbate’ which is used as reductant and it has been revised in manuscript.
Comment 2) If possible, please add the data of XPS spectrum of reduced (used) Ni catalyst (Ni(0)).
Response: We thank the reviewer for the comments. The data of XPS spectrum of used Ni catalyst can’t be collected at this time .
3) Please show a reaction results for only reductant (without Ni catalyst) as a control.
Response: We thank the reviewer for the comments. No product was obtained in the absence of GPT-Ni catalyst (Table 1, entry 14).
Round 2
Reviewer 1 Report
I repeat my request:
1) Figure 2 is too small and completely illegible after printing.
2) XRD data should be presented legibly, not as a drawing of overlapping peaks.
3) Based on TEM the authors should make a distribution of size of the obtained sample.
What is known about the composition of the catalyst?. What is the theoretical content of nickel in the sample ?. What do the TG results say about the composition?
The authors wrote that they did the TG test in the range from in the 40‐900 °C temperature range (174) so why they showed the results only in the 40‐600 °C temperature range ?.
Author Response
please see attachment .
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The authors have performed the revision of the manuscript and most of my questions were clarified. However, attending to the low size of the nanocatalyst particles , <10 nm, it should be specified in the paper, which filtration system/membrane were used in catalyst preparation and recycling experiments and if pressures were used in filtration.
Author Response
Comment The authors have performed the revision of the manuscript and most of my questions were clarified. However, attending to the low size of the nanocatalyst particles, <10 nm, it should be specified in the paper, which filtration system/membrane were used in catalyst preparation and recycling experiments and if pressures were used in filtration.
Response: We thank the reviewer for the constructive comments. After completion of the reaction, the catalyst was collected by centrifugal separation and washed with H2O and ether twice. The separated catalyst was recharged with a fresh substrate for the next round. It has been revised in manuscript and marked in red.
