[6-(Furan-2-yl)-2,2′-bipyridine]bis(triphenylphosphine) Copper(I) Tetrafluoroborate
, John C. Plakatouras 1,2 and Gerasimos Malandrinos 1,*
Round 1
Reviewer 1 Report
The paper is presented in the same manner as for previously published Kouvatsis, P.; Glykos, D.; Plakatouras, J.C.; Malandrinos, G. [6-(Thiophen-2-yl)-2,2′ -bipyridine]bis(triphenylphosphine) Copper(I) Tetrafluoroborate. Molbank 2023, 2023, M1605. https://doi.org/10.3390/M1605. The newly synthesized compound Cu(L)(PPh3)2][BF4] (L = 10 (6-(furan-2-yl)-2,2’-bipyridine), PPh3 = triphenylphospine) should be discussed in one publication together with the thiophenyl derivative, then their properties could be compared. Publishing each compound separately is, in my opinion, only increasing the achievements of the authors. Very short abstract, not very informative. Table 1 presents 1HNMR data for the ligand, the authors measured the spectrum of this compound or did they take these data from the literature? What about 13CNMR? Since the authors compare the 1HNMR of the ligand to the complex, then why is there no comparison of the IR spectra? Something wrong happened to table 2 - line 68. The conclusion part is also very concise and says nothing about what will be done next on this topic.
Author Response
We would like to express our gratitude to Reviewer 1 for his/her valuable comments. We provide the following responses:
Comment: The newly synthesized compound [Cu(L)(PPh3)2][BF4] (L = 10 (6-(furan-2-yl)-2,2’-bipyridine), PPh3 = triphenylphospine) should be discussed in one publication together with the thiophenyl derivative, then their properties could be compared. Publishing each compound separately is, in my opinion, only increasing the achievements of the authors.
Answer: Our prior publication on the thiophenyl derivative and the insights gained from it inspired us to design and synthesize a similar compound with a furyl derivative to examine the impact of changing the heteroatom on photophysical behavior. These two compounds were not obtained simultaneously, which is why we opted to publish the results separately as a short Note in Molbank (experimental data records for previously unpublished single molecules, with one compound per paper). In this context, we compare crucial properties, such as emission maximum and photoluminescence quantum yield. Additionally, regarding molecular structure, we emphasize the significant elongation of the Cu-N2 bond (N2 belongs to the substituted pyridyl ring).
Comment: Very short abstract, not very informative
Answer: We have revised the abstract to better convey the key findings of this study.
Comment: Table 1 presents 1HNMR data for the ligand, the authors measured the spectrum of this compound or did they take these data from the literature? What about 13CNMR? Since the authors compare the 1HNMR of the ligand to the complex, then why is there no comparison of the IR spectra?
Answer: The literature data for the ligand was only used to verify the success of the synthetic procedure. We synthesized the compound and recorded the spectra (1H, COSY, NOESY NMR), and the data extracted from our analysis are documented in Table 1. 13C NMR was unnecessary for assignment in these simple molecules. The existence and integrity of the complex in solution was confirmed through 1H NMR and HR-ESI-MS data. The IR spectrum was recorded using powder prepared from the compound crystals. Given that the molecular structure of the compound was determined via X-ray crystallography, a comparison of IR spectra (L vs complex) was deemed unnecessary.
Comment: Something wrong happened to table 2 - line 68
Answer: We have now re-provided Table 2.
Comment: The conclusion part is also very concise and says nothing about what will be done next on this topic.
Answer: The conclusion section has been expanded and now includes details about our future research goals.
Reviewer 2 Report
Gerasimos Malandrinos and coworkers have reported a Short Note on [6-(Furan-2-yl)-2,2’-bipyridine]bis(triphenylphosphine) copper(I) tetrafluoroborate. Synthesis, characterization, and absorption spectrum were described.
Although similar molecules are reported, the exact compound [6-(Furan-2-yl)-2,2’-bipyridine]bis(triphenylphosphine) copper(I) tetrafluoroborate was not reported.
Some comments should be considered before the manuscript is accepted for publication.
(1) The crystal table must be provided at least in the Supporting Information.
(2) The Figure quality of Figure 1 should be improved.
(3) The authors should mention similar structures reported in the literature.
(4) The crystallization procedure should be reported along with the synthetic process.
(5) The absorption and emission spectra look broad. They can try to sharpen them.
(6) Table 2 is not completed. Please provide.
(7) The compound is synthesized in a very small scale (15.7 mg, 0.05 mol). The author should report if that is possible in a larger scale.
Author Response
Reviewer 2
We would like to express our appreciation to reviewer 2 for his/her valuable comments. We respond as follows:
Comment 1: The crystal table must be provided at least in the Supporting Information.
Answer: Although a summary of the crystal data is given in section 3.3, we have additionally provided Table S1 (supplementary materials).
Comment 2: The Figure quality of Figure 1 should be improved.
Answer: The quality of Figure 1 has been enhanced.
Comment 3: The authors should mention similar structures reported in the literature.
Answer: We have now included a few more references. In this version, references No. 9, 11, 15-19, which report similar structures, were used to compare the Cu-N and Cu-P bond distances. The studied compound adopts a very common and predictable geometry for complexes of this type; therefore, we deemed it unnecessary to expand our discussion on this topic. The only differentiation detected in our structure is the notable elongation of the Cu-N2 bond (N2 belongs to the substituted pyridyl ring), which has already been reported.
Comment 4: The crystallization procedure should be reported along with the synthetic process.
Answer: The crystallization procedure is now included in the section 3.4 (synthesis of the complex)
Comment 5: The absorption and emission spectra look broad. They can try to sharpen them
Answer: In fact, the diffuse reflectance and emission spectra of Cu(N^N)(PPh3)2 complexes in the solid state at room temperature are broad (please refer to references 9, 17-18). Broad, unstructured bands in the emission spectrum possibly denote deactivation through a 3MLCT state (phosphorescence).
Comment 6: Table 2 is not completed. Please provide.
Answer: We have now re-provided Table 2 in its entirety.
Comment 7: The compound is synthesized in a very small scale (15.7 mg, 0.05 mmol). The author should report if that is possible in a larger scale.
Answer: We have successfully synthesized the compound on a scale of up to 0.1 mmol. As the complex's synthetic procedure is relatively simple, we believe that it is possible to further increase the scale.
Round 2
Reviewer 1 Report
the corrections made are sufficient, the publication can be accepted
Author Response
We would like to express our gratitude to the reviewer 1 for his/her valuable time and insightful comments
Reviewer 2 Report
The authors have addressed the comments pointed out by me. He has provided some additional information. I therefore would like the manuscript to be accepted for publication in Molbank after some minor changes.
Comment 1: The crystal table must be provided at least in the Supporting Information.
Answer: Although a summary of the crystal data is given in section 3.3, we have additionally provided Table S1 (supplementary materials).
Reply: Thanks for providing the Table.
Comment 2: The Figure quality of Figure 1 should be improved.
Answer: The quality of Figure 1 has been enhanced.
Reply: It looks good.
Comment 3: The authors should mention similar structures reported in the literature.
Answer: We have now included a few more references. In this version, references No. 9, 11, 15-19, which report similar structures, were used to compare the Cu-N and Cu-P bond distances. The studied compound adopts a very common and predictable geometry for complexes of this type; therefore, we deemed it unnecessary to expand our discussion on this topic. The only differentiation detected in our structure is the notable elongation of the Cu-N2 bond (N2 belongs to the substituted pyridyl ring), which has already been reported.
Reply: Thank you for providing some more information on literature reports. I wish the authors could provide more examples so that it would be easier for the readers to get some adequate information about similar structures. However, it is OK.
Comment 4: The crystallization procedure should be reported along with the synthetic process.
Answer: The crystallization procedure is now included in the section 3.4 (synthesis of the complex)
Reply: Looks good. The author should mention whether the yield is of the precipitate or of the single crystal.
Comment 5: The absorption and emission spectra look broad. They can try to sharpen them
Answer: In fact, the diffuse reflectance and emission spectra of Cu(N^N)(PPh3)2 complexes in the solid state at room temperature are broad (please refer to references 9, 17-18). Broad, unstructured bands in the emission spectrum possibly denote deactivation through a 3MLCT state (phosphorescence).
Reply: The author could mention them in the text for the readers.
Comment 6: Table 2 is not completed. Please provide.
Answer: We have now re-provided Table 2 in its entirety.
Reply: Looks good.
Comment 7: The compound is synthesized in a very small scale (15.7 mg, 0.05 mmol). The author should report if that is possible in a larger scale.
Answer: We have successfully synthesized the compound on a scale of up to 0.1 mmol. As the complex's synthetic procedure is relatively simple, we believe that it is possible to further increase the scale.
Reply: Looks good. The authors should mention them in the text.
Author Response
We would like to thank the reviewer 2 for taking the time and effort to reevaluate our manuscript. Your expertise has greatly contributed to the improvement of this work.
Minor changes (highlighted in red)
- The reported yield is calculated using the mass of the precipitate and is mentioned in section 3.4
- References reporting examples of broad unstructured emission spectra are now mentioned in section 2.4 (references 9, 15, 16 in the new version)
- Concerning the synthesis scale, we now provide this information in section 3.4
