Quinine Charge Transfer Complexes with 2,3-Dichloro-5,6-Dicyano-Benzoquinone and 7,7,8,8-Tetracyanoquinodimethane: Spectroscopic Characterization and Theoretical Study
, Tarek A. Yousef 3,4, Samir T. Gaballah 5, Atef M. Homoda 2, Rashad Al-Salahi 1, Haya I. Aljohar 1 and Haitham AlRabiah 1,*Round 1
Reviewer 1 Report
The paper Quinine charge transfer complexes with 2,3-Dichloro-5,6-Dicy- ano- Benzoquinone and 7,7,8,8-Tetracyanoquinodimethane: Spectroscopic characterization and theoretical study can be accepted after introducing the following changes:
Results chapter: Authors writes: "The electronic structure of B is less stable than the neutral DDQ itself. The structure is presumed to be at equilibrium with C," - it is connected with scheme 1, but it is not clear what is A, B or C- it should be explained.
Figure 2. 400 ppm of Q-TCNQ complex, (2) 400 ppm of donor... what 400 ppm means?
The energy of CT complex.
Authors write: "the stability of the CT complexes in the ground state is indicated by the resonance energy. It was found that the resonance energies of Q-DDQ and Q-TCNQ are 0.112 ev and 0.194 ev, respectively." the values need a comment, just like other data.
Figure 4. The 1:1 Benesi-Hildebrand Plot for Q- DDQ and Q-TCNQ CT complexes system. (Ca 228 and Cd: initial concentration of acceptor, and donor, and A: absorbance).- the R2 of 0.91 is rather low indicating the low results matching
3.2.1. Infrared. This chapter is too long. In my opinion, the main values (Quinine FTIR, DDQ, TCNQ, quinine-DDQ CT complex and quinine-TCNQ CT complex) should be placed in Table, and the and the differences between them described in the short commentary.
The same with 3.2.2.1.1. H NMR chapter lines 358-390 can be removed
Figures 7 and 8- why they are placed after NMR chapter?
Geometry optimization chapter. Tables 4-8, 10-12 can be shifted to Supplementary Materials.
3.3.4. Quantum chemical parameters and Frontier molecular orbitals There is something wrong with equations 1-5- the editing problems maybe?
Editing errors should be removed.
Author Response
Reviewer 1
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Results chapter: Authors writes: "The electronic structure of B is less stable than the neutral DDQ itself. The structure is presumed to be at equilibrium with C," - it is connected with scheme 1, but it is not clear what is A, B or C- it should be explained |
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This sentence has been deleted, it was typing mistake. |
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Figure 2. 400 ppm of Q-TCNQ complex, (2) 400 ppm of donor... what 400 ppm means? |
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The ppm is changed to µg/ml |
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The energy of CT complex. Authors write: "the stability of the CT complexes in the ground state is indicated by the resonance energy. It was found that the resonance energies of Q-DDQ and Q-TCNQ are 0.112 ev and 0.194 ev, respectively." the values need a comment, just like other data. |
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The comment has been inserted (L276-278) |
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Figure 4. The 1:1 Benesi-Hildebrand Plot for Q- DDQ and Q-TCNQ CT complexes system. (Ca 228 and Cd: initial concentration of acceptor, and donor, and A: absorbance).- the R2 of 0.91 is rather low indicating the low results matching |
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The correlation coefficient (R) has been rechecked and the corrected values has been inserted (0.96 and 0.98 for Q-DDQ and Q-TCNQ Resp). |
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2 Infrared. This chapter is too long. In my opinion, the main values (Quinine FTIR, DDQ, TCNQ, quinine-DDQ CT complex and quinine-TCNQ CT complex) should be placed in Table, and the and the differences between them described in the short commentary |
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The IR of Q, DDQ and TCNQ has been moved into supplementary material (L310 to L324). |
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The same with 3.2.2.1.1. H NMR chapter lines 358-390 can be removed |
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The H NMR data for Q, DDQ and TCNQ has been moved to supplementary section (lines 364-396). The 13 C NMR L448-450) has been moved to supplementary materials. |
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Figures 7 and 8- why they are placed after NMR chapter? |
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Figure 7 and 8 have been inserted into the correct place (computational section) |
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Geometry optimization chapter. Tables 4-8, 10-12 can be shifted to Supplementary Materials |
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Done Table 5-8 and 10-12shifted to supplementary material Tables (S1-S4) and (S5-S7). |
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3.3.4. Quantum chemical parameters and Frontier molecular orbitals There is something wrong with equations 1-5- the editing problems maybe? Editing errors should be removed. |
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All Quantum chemical parameters and Frontier molecular orbitals revised carefully and now is correct. |
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Authors provided the comprehensive study of charge-transfer complexes of quinine with two molecules. The composition of complexes, their stability were investigated by the wide scope of advanced methods. The manuscript represents valuable research in the field in organic and physical chemistry, moreover it suits well to the topics of Applied Chemistry Journal.
The manuscript can be accepted after minor revisions:
- It would be better it authors outline what problem with quantitative estimation such a drug as quinine prompted them to conduct the current research.
- Comparison the chemical shifts (1H NMR and 13C NMR) in free DDQ or TNCQ and the corresponding complexes with quinine is also important. I would recommend adding this data in 2.2 part.
- Line 357 - 3.2.2.1. 1H NMR; line 440 - 3.2.2.2. 13C NMR
- Lines 711-720 should be deleted
- Lines 653-689, 692-709 should be reconsidered. Author Contributions: authors names and their impact in the whole work; Conflicts of Interest: only one phrase, and so on.
- Line 652 – “6. Patents” what does it mean/
- I suppose most of readers are interested in some future prospects in conclusion part. Is current research is helpful for study DDQ or TNCQ complexes with other alkaloids?
Author Response
Reviewer 2
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It would be better if authors outline what problem with quantitative estimation such a drug as quinine prompted them to conduct the current research. |
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Done |
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Comparison the chemical shifts (1H NMR and 13C NMR) in free DDQ or TNCQ and the corresponding complexes with quinine is also important. I would recommend adding this data in 2.2 part. |
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The comparison data was presented in Table 3 for 1H NMR and Tables 4 and 5 for 13C NMR. |
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Line 357 - 3.2.2.1. 1H NMR; line 440 - 3.2.2.2. 13C NMR |
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All comments were fixed. |
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Lines 711-720 should be deleted |
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Lines 711-720 have been deleted. |
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Lines 653-689, 692-709 should be reconsidered. Author Contributions: authors names and their impact in the whole work; Conflicts of Interest: only one phrase, and so on. |
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Done |
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Line 652 – “6. Patents” what does it mean/ |
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Patents has been deleted, it was type mistake. |
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I suppose most of readers are interested in some future prospects in conclusion part. Is current research is helpful for study DDQ or TNCQ complexes with other alkaloids |
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Done |
Author Response File: Author Response.pdf
