Photooxidative Dehydrogenation of Chiral Ir (III) Amino Acid Complexes Based on [Λ-Ir(ppy)2(MeCN)2](PF6)
Round 1
Reviewer 1 Report
The manuscript 2605964 “Synthesis and Photooxidative Dehydrogenation Property of Chiral Ir(III) Amino Acid Complexes Based Conveniently Synthesized [Λ-Ir(ppy)2(MeCN)2](PF6)” by Suyang Yao, Yanxi Pu, Lulu Ren, Manli Cao, Baohui Ye describes the synthesis, characterization of a series of the chiral amino acid (AA) complexes of the trivalent iridium and a number of corresponding imino acids complexes. The latter were obtained by photo-oxidative dehydrogenation coordinated molecule of AA.
The manuscript cannot be published in the present form, as it requires a small but essential revision.
Unfortunately, the molecular and crystal structure was determined only for one pair of complexes based on D-threonine. Therefore, the characterization of the solid products requires additional study using FTIR, moreover, in comparison with the spectra of the free ligand and the starting complex.
When describing the synthesis of AA complexes, the authors indicated the number of significant figures for the molar amounts of substances, which does not correspond to the weighing accuracy.
It is not clear why a twofold excess of amino acid was used if there is only one molecule of deprtonated AA in the final complex. Why was a sufficiently large excess of sodium methoxide used, or was the methanol not anhydrous before use?
It is necessary indicate the yield of products not only in percent, but also in mg.
A number of remarks have arisen regarding the study of the kinetics of photoinduced oxidative dehydrogenation. Despite the fact that the kinetic of this process is linear, three points are probably not enough for reliable determination of the reaction rate constants, for which a confidence interval should be given in Table 1 to make it clear with what accuracy they were determined. In addition, the experimental plots obtained from the NMR data and their simulated straight lines should be presented.
Additional comments and suggestions can be found directly in the pdf-file of the manuscript
Comments for author File: 
Comments.pdf
The quality of the English language is not bad, although if the authors diversify the text with synonyms the content of the article would greatly benefit from this.
However, the abstract is very poorly written, it is very difficult to read.
Author Response
We sincerely thank the referee for your comments of our work. The responses to the reviewer were listed below.
- Comments 1: Unfortunately, the molecular and crystal structure was determined only for one pair of complexes based on D-threonine. Therefore, the characterization of the solid products requires additional study using FTIR, moreover, in comparison with the spectra of the free ligand and the starting complex.
Response: Thanks for your suggestion. We have done the FTIR spectra of all D-configurated amino acid complexes([Λ-[Ir(ppy)2(D-AA)]) and their corresponding imino acid complexes. Meanwhile, the FTIR spectra of threonine ligand, chiral metal template [Λ-Ir(ppy)2(MeCN)2] PF6, Λ-Ir(ppy)2(Thr-2H) and [Λ-[Ir(ppy)2(D-Thr)] are also include in supporting information (figure S35).
- Comments 2: When describing the synthesis of AA complexes, the authors indicated the number of significant figures for the molar amounts of substances, which does not correspond to the weighing accuracy
Response: Thank you for pointing this out. The data has been corrected.
- Comments 3: It is not clear why a twofold excess of amino acid was used if there is only one molecule of deprtonated AA in the final complex. Why was a sufficiently large excess of sodium methoxide used, or was the methanol not anhydrous before use?
Response: Thanks for your nice comments. The use of excess amino acids and sodium methoxide is able to shorter the reactions time of the coordination process. In fact, when 1 equiv amino acids and 1 equiv sodium methoxide were using, we can also obtain the amino acid complexes. However, it will take a longer reaction time.
- Comments 4: It is necessary indicate the yield of products not only in percent, but also in mg.
Response: Thank you for pointing this out. We have added the weight of products.
- Comments 5: A number of remarks have arisen regarding the study of the kinetics of photoinduced oxidative dehydrogenation. Despite the fact that the kinetic of this process is linear, three points are probably not enough for reliable determination of the reaction rate constants, for which a confidence interval should be given in Table 1 to make it clear with what accuracy they were determined. In addition, the experimental plots obtained from the NMR data and their simulated straight lines should be presented.
Response: We included the experimental plots from the NMR data and their simulated straight lines of Λ- [Ir(ppy)2(D-Ala)] and Λ-[Ir(ppy)2(L-Ala)] in manuscript (figure 4, figure 5). The spectra of kinetic study and the details of fitness for other complexes are also include in supporting information.
- Comments 6: Additional comments and suggestions can be found directly in the pdf-file of the manuscript
Response: We agree with this comment. We have corrected the manuscript according to your suggestions.
- Comments 7: The quality of the English language is not bad, although if the authors diversify the text with synonyms the content of the article would greatly benefit from this. However, the abstract is very poorly written, it is very difficult to read.
Response: Thank you for pointing this out. We have extensively modified the language of the all manuscript according to your suggestions.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The paper describes the use of chiral at metal Ir(III) complexes with 2 cylometalated phenylpyridine units that display enantioselectively oxidative deshydrogenation of aminoacids under visible light to afford iminoacids. Previous closely related work was published by this research group using 2 cyclometalated phenyl quinoline units on the Ir(III) center that displayed the same properties, however less efficiently because some coupling reaction occured between the cycloiridated ligands and the amino acids.
The results presented are interesting and will surely attract the attention of many colleagues working with organometallic templates. The work was apparently well peformed, the paper was well written and its publication in inorganics is recommended.
Minor improvements are as follows :
no assignements were made for the 1H NMR spectra, this is usually accepted, however, as one NH proton of the amino unit of the coordinated aminoacids as been identified the second NH should be easily identified too by a simple irradiation experiment. The signals should all be of the form doublets of doublets as the 2 NH protons are inequivalent.
Moderate editing of english might be required. A few examples :
line 49 : 'Their study first found' should read : 'Their study first showed'
line 51-52 : this phrase might be better understand in the following form : 'However the metal complexes to which the amino acids were coordinated... were all racemic'
line 178 : 'we could know' should read : 'we found'
line 197 : 'signals which decrease two units' is difficult to understand.
Author Response
Please see the attachment
Author Response File: Author Response.docx
Reviewer 3 Report
Manuscript nr. inorganics-2605964
Entitled: Synthesis and Photooxidative Dehydrogenation Property of Chiral Ir (III) Amino Acid Complexes Based Conveniently Synthesized [Λ-Ir(ppy)2(MeCN)2](PF6)
This is a well-conducted scientific study, done in a thorough manner and expressed concisely. Therefore, the manuscript is suitable for Inorganics after considering the below comments.
Scheme 1. 65please add the space°C, and passim.
Figure 2. „Mass spectrum of chiral complexes based on alaninę” change into „Mass spectra of chiral complexes based on alanine.” Additionally, please show the proposition of fragmentation pathways. Please add the structure on each spectrum.
Author Response
We sincerely thank the referee for your recognitions. The responses to the reviewer were listed below.
Comments 1: Entitled: Synthesis and Photooxidative Dehydrogenation Property of Chiral Ir (III) Amino Acid Complexes Based Conveniently Synthesized [Λ-Ir(ppy)2(MeCN)2](PF6)
This is a well-conducted scientific study, done in a thorough manner and expressed concisely. Therefore, the manuscript is suitable for Inorganics after considering the below comments.
Scheme 1. 65please add the space°C, and passim.
Response: Thank you for pointing this out. We have corrected the scheme.
Comments 2: Figure 2. „Mass spectrum of chiral complexes based on alaninę” change into „Mass spectra of chiral complexes based on alanine.” Additionally, please show the proposition of fragmentation pathways. Please add the structure on each spectrum.
Response: Thanks for your nice comments. We have corrected the expression of mass spectra and added the structure and proposition of fragmentation in each mass spectrum (figure 3).
Author Response File: Author Response.docx
Reviewer 4 Report
The authors reported the photooxidative dehydrogenation of 2 Chiral Ir (III) Amino Acid Complexes Based Syn- 3 thesized [Λ-Ir(ppy)2(MeCN)2](PF6). The submission requiresmajor revision taking into account the following points:-
1. The title should be revised to be informative. Redundant words such as ‘Synthesis and’; ‘ Property’; and ‘Conveniently Synthesized’ should be removed.
2. The study lacks the motivation to highlight the applications that could be obtained from these complexes.
3. Assign other peaks in HNMR, Figure 2.
4. FT-IR spectra of the complex before and after dehydrogenation should be added.
5. The chemical structure of the compounds should be assigned and added beside the mass spectra, Figure 2.
6. A comparison with other studies should be discussed and summarized in a Table.
7. The language should be revised and typos should be corrected.
Native speaker or professional service should be conducted.
Author Response
We sincerely thank the referee for your nice comments. The responses to the reviewer were listed in the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 4 Report
none
The authors addressed most of the comments and the revised version can be accepted.
