Magnetic and Luminescence Properties of 8-Coordinated Pyridyl Adducts of Samarium(III) Complexes Containing 4,4,4-Trifluoro-1-(naphthalen-2-yl)-1,3-butanedionate
, Saskia Speed 2, Ánnia Tubau 2, Roland C. Fischer 3 and Salah S. Massoud 4,5,*Round 1
Reviewer 1 Report
This manuscript reports a new series of 8-coordinated samarium(III) complexes together with crystal structures, photoluminescent properties, and magnetic properties. The compounds showed luminescence emission in the visible and NIR regions, and the results were well investigated. Magnetic properties (temperature dependence and magnetic field dependence were also measured and reported.) The experiments were well carried out.
Is there a correlation between structure and magnetic properties in the compound series?
I see simulations of magnetic susceptibility and magnetization in textbooks on magnetism. Isn't it actually possible to simulate the data? Wouldn't it be better to run a simulation?
New correlations might be found between the structure and the magnetic parameters obtained from the simulation.
"Magnetization dependence" in line 347 should be "Field dependence of magnetization". Please modify the sentence appropriately.
Why is magnetization not saturated? Adding a comment may help the reader.
Author Response
Reviewer #1
Comments and Suggestions for Authors
This manuscript reports a new series of 8-coordinated samarium(III) complexes together with crystal structures, photoluminescent properties, and magnetic properties. The compounds showed luminescence emission in the visible and NIR regions, and the results were well investigated. Magnetic properties (temperature dependence and magnetic field dependence were also measured and reported.) The experiments were well carried out.
Is there a correlation between structure and magnetic properties in the compound series?
We have not found this correlation. In the new version of the paper we have found the l spin orbit coupling parameter for all of the four compounds but it is similar for all of them.
I see simulations of magnetic susceptibility and magnetization in textbooks on magnetism. Isn't it actually possible to simulate the data? Wouldn't it be better to run a simulation?
We have tried to fit/simulate the data with the equation of new added reference 69 (O. Kahn. Molecular Magnetism). But we obtain impossible l values (1x1032)
New correlations might be found between the structure and the magnetic parameters obtained from the simulation.
"Magnetization dependence" in line 347 should be "Field dependence of magnetization". Please modify the sentence appropriately.
Thank you, this was fixed
Why is magnetization not saturated? Adding a comment may help the reader.
Please see the last paragraph on p-17 but we do not have a conceiving reason for the magnetic unsaturation.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The manuscript (MS) entitled «Magnetic and Luminescence Properties of 8-Coordinated Pyridyl Adducts of Samarium(III) Complexes Containing 4,4,4-Trifluoro-1-(naphthalen-2-yl)-1,3-butanedionate » by Franz A. Mautner et al. is devoted to a synthesis of series of Sm3+ complexes with 4,4,4-trifluoro-1-(naphthalen-2-yl)-1,3-butanedionate and different bipyridines as ancillary ligands and investigation of their structure, photophysical and magnetic properties. In general, the article might be interesting for the readership of the Journal. To my opinion, this MS need to be significantly improved before resubmission.
Firstly, the introduction part should be revised completely. The discussion about general fields of Sm application should be removed and focused on the Sm3+ diketonates and their properties. Since 4,4,4-trifluoro-1-(naphthalen-2-yl)-1,3-butanedione is rather a popular ligand for preparation of coordination compounds of lanthanides, and particular, Sm3+ some previously obtained results should be discussed ( please, see for example,10.1021/ja073970w, 10.1021/ic8020782, 10.1016/0022-328X(94)05081-L). A short review of coordination ability of 4,4,4-trifluoro-1-(naphthalen-2-yl)-1,3-butanedione as well as a detailed description of its photophysical properties can be found in ref. 10.1016/j.dyepig.2021.109701.
Page 1, 38-39
«…samarium(III) compounds exhibit orange/red light emission [2-10], but other lights
are rare [10-13].»
This statement is vague: the emission of Sm3+ is originated from distinct f-f transition, and therefore spectral lines wavelengths are strictly determined. Different colors can be obtained only if additional to Sm emissions bands are admixing to the resulting emission (e.g. ligand luminescence, etc). Please, reformulate or delete this paragraph. Thus, references 10-13 are not relevant. Reference 6 is not relevant also, since non-luminescent complexes of divalent Sm are described there. The other references in the Introduction thus must be carefully checked for relevancy.
Page 2, 63-65
«…this may lead to tuning the position of the ligands’ triplet levels to give good energy transfer between the diketonato ligands and the lanthanide ion [44-46] through reducing nonradiative quenching of lanthanide luminescence [44-50]»
The value of energy of triplet level and nonradiative relaxation processes ( not quenching, quenching cannot be « nonradiative» !) are two independent factors, which can affected on the efficiency of the luminescence. Please, see for example, ref. 39 for details. This part should be revised.
Page 2, 59
«where the resulting coordinated β‐diketonates act as efficient “antenna ligands” 59
for lanthanides emitting in the UV, visible and NIR region [22-43]. »
No complexes of lanthanides with organic ligands, emitting in the UV region are known up to date. The only suitable UV-emitting ion, Gd3+ cannot be sensitized with any organic antenna due to the very high energy of the corresponding resonant level of Gd3+.
Page 3, paragraph 2.3line 119,
it should be solid-state InGaAs detector, not a «solid indium/gallium/arsenic detector», since InGaAs is a compound, a semiconductor, not a mixture of metals.
line 121 « Instrument in the phosphorescence mode using a 450 W xenon pulsed lamp (1.5 ns pulse)» Please, check. As a rule, Fluorolog 3 instrument is equipped by 60W xenon pulsed lamp with a typical pulse duration of 60-80 microseconds. This time is automatically subtracted from overall decay time by setting of a «delay» parameter in the FluoroEssence software ( check the instrument’s manual).
Page 4, paragraph 2.4
The elemental analysis data must be presented with two decimal points ( e.g. N 2.5 7%, not N 2.6 %).
Page 7, paragraph 3.3
Line 235-235
«an intense broad band over the 350-400 nm region, indicating the same 235 modes of O/N chelation.»
UV-vis absorption spectra are not really sensitive to the mode of coordination, and line shape mainly depends upon pi-pi and n-pi transitions in the ligands. They are not suitable for the determination of the coordination model, incontrast with luminescent spectra.
Page 8,
Line 265
«Ratio values of 6.25, 4.52, 4.62 and 4.17 were determined in the 1-4 compounds, respectively.»
In which units and these integrals were calculated? One must use energy units to calculate integrals correctly. Consequently, spectra must be presented in energy units first ( e.g. cm-1) to calculate correct integrals. At which temperature data were collected – the integral values for room temperature and 77K may be significantly different.
Page 8,
Line 272
«The difference in the hypersensitive band intensity of 1-4 compounds, is 270 also perceived in the emission colour, that could be seen by naked eye under UV lamp and according to the CIE diagram represented in Figure 4.»
The contribution of the hypersensitive transition 4G5/2→6H9/2 (650 nm) for complex 1 is greater than for the others. And it color should have been more «red». However, in the photo and diagram, the emission of the complex is closer to white than the others, which means that the contribution of luminescence, which the authors associate with the ligand environment in the region up to 550 nm, plays a greater role, see Figure 3(1). A full spectrum with the region 400-550 nm should be provided to explain the peculiarities of luminescence.
Page 9,
Line 278
«the magnetic dipole allowed transition 4G5/2→6H7/2 is taken as a reference, and it splits to a maximum of J+1/2 Stark components for compounds 1-4 according to symmetries lower than cubic for 280 J half-integer values»
The splitting is usually given for the level, not for the transition. In the spectrum, one can see less than the maximum number of splitting lines components ( maximum number of components is equal to 3x4). It is worth constructing an assumption from the opposite, to show that the number of observed components is greater than in the case of a cubic one. For a cubic type with a half-integer J, the splitting will be: J=1/2,3/2 -> 1; J=5/2 -> 2; J=7/2,9/2 -> 3 [Please, see B. G. Wybourne, Spectroscopic Properties of Rare Earths, John Wiley, 1965 and 10.1016/j.dyepig.2020.108558]
Page 9,
Line 298
"to the ground state 4GJ, in the visible range takes place"
It should be 6HJ
Page 10, Figure 5
The luminescence decay data are commonly presented in a semi-logarithmic scale. This scale in much convenient for the decay analysis. Insufficient data collection time, the deviations from monoexponential decay law, etc can be easily detected on semi-logarithmic plots. Please, present all data in this scale along with the results of their fitting. Now it is not clear if the kinetics are really monoexponential. For details, please, see for example, 10.1016/j.saa.2019.117503.
The authors claim that the 4G7/2 and 4F3/2 levels do not participate in the luminescence of the ion, since nonradiative relaxation immediately passes from them to 4G5/2. But if this statement was made, it should be confirmed by kinetic measurements. Quite possible, that after careful analysis the kinetic decays may have a two-exponential character. Moreover, there is a weak transition from the 4F3/2 level, and this fact does not match the initial statement.
Author Response
Reviewer #2
Comments and Suggestions for Authors
The manuscript (MS) entitled «Magnetic and Luminescence Properties of 8-Coordinated Pyridyl Adducts of Samarium(III) Complexes Containing 4,4,4-Trifluoro-1-(naphthalen-2-yl)-1,3-butanedionate » by Franz A. Mautner et al. is devoted to a synthesis of series of Sm3+ complexes with 4,4,4-trifluoro-1-(naphthalen-2-yl)-1,3-butanedionate and different bipyridines as ancillary ligands and investigation of their structure, photophysical and magnetic properties. In general, the article might be interesting for the readership of the Journal. To my opinion, this MS need to be significantly improved before resubmission.
Firstly, the introduction part should be revised completely. The discussion about general fields of Sm application should be removed and focused on the Sm3+ diketonates and their properties. Since 4,4,4-trifluoro-1-(naphthalen-2-yl)-1,3-butanedione is rather a popular ligand for preparation of coordination compounds of lanthanides, and particular, Sm3+ some previously obtained results should be discussed ( please, see for example,10.1021/ja073970w, 10.1021/ic8020782, 10.1016/0022-328X(94)05081-L). A short review of coordination ability of 4,4,4-trifluoro-1-(naphthalen-2-yl)-1,3-butanedione as well as a detailed description of its photophysical properties can be found in ref. 10.1016/j.dyepig.2021.109701.
The reviewer is right, the first five lines in the introduction were deleted together with the reference in this part and the focus was on some of the applications of lanthanides and their coordination properties with emphasize on the beta-diketonate ligands.
Page 3 and the first two references indicated by the reviewer were inserted (52 & 53)
«…samarium(III) compounds exhibit orange/red light emission [2-10], but other lights
are rare [10-13].»
This statement is vague: the emission of Sm3+ is originated from distinct f-f transition, and therefore spectral lines wavelengths are strictly determined. Different colors can be obtained only if additional to Sm emissions bands are admixing to the resulting emission (e.g. ligand luminescence, etc). Please, reformulate or delete this paragraph. Thus, references 10-13 are not relevant. Reference 6 is not relevant also, since non-luminescent complexes of divalent Sm are described there. The other references in the Introduction thus must be carefully checked for relevancy.
Page 2, 64-66
«…this may lead to tuning the position of the ligands’ triplet levels to give good energy transfer between the diketonato ligands and the lanthanide ion [44-46] through reducing nonradiative quenching of lanthanide luminescence [44-50]»
The value of energy of triplet level and nonradiative relaxation processes ( not quenching, quenching cannot be « nonradiative» !) are two independent factors, which can affected on the efficiency of the luminescence. Please, see for example, ref. 39 for details. This part should be revised.
Ref. 38 & 39
«where the resulting coordinated β‐diketonates act as efficient “antenna ligands” 59
for lanthanides emitting in the UV, visible and NIR region [22-43]. »
This part was revised and UV region was deleted , ref 21-42
No complexes of lanthanides with organic ligands, emitting in the UV region are known up to date. The only suitable UV-emitting ion, Gd3+ cannot be sensitized with any organic antenna due to the very high energy of the corresponding resonant level of Gd3+.
Thank you for this important point, sentence was revised (p-, 2nd line), Ref 38
it should be solid-state InGaAs detector, not a «solid indium/gallium/arsenic detector», since InGaAs is a compound, a semiconductor, not a mixture of metals.
line 121 « Instrument in the phosphorescence mode using a 450 W xenon pulsed lamp (1.5 ns pulse)» Please, check. As a rule, Fluorolog 3 instrument is equipped by 60W xenon pulsed lamp with a typical pulse duration of 60-80 microseconds. This time is automatically subtracted from overall decay time by setting of a «delay» parameter in the FluoroEssence software ( check the instrument’s manual).
This was fixed, page 6, line 7
The elemental analysis data must be presented with two decimal points ( e.g. N 2.5 7%, not N 2.6 %).
These were fixed, pages 8 & 9.
«an intense broad band over the 350-400 nm region, indicating the same 235 modes of O/N chelation.»
UV-vis absorption spectra are not really sensitive to the mode of coordination, and line shape mainly depends upon pi-pi and n-pi transitions in the ligands. They are not suitable for the determination of the coordination model, incontrast with luminescent spectra.
We absolutely agree with the referee in this statement; therefore the sentence was revised (p-11, first two lines in section 3.3.)
«Ratio values of 6.25, 4.52, 4.62 and 4.17 were determined in the 1-4 compounds, respectively.»
In which units and these integrals were calculated? One must use energy units to calculate integrals correctly. Consequently, spectra must be presented in energy units first ( e.g. cm-1) to calculate correct integrals. At which temperature data were collected – the integral values for room temperature and 77K may be significantly different.
Units of energy were used to calculate these ratios, which of course have no units (p-13, last paragraph).
«The difference in the hypersensitive band intensity of 1-4 compounds, is 270 also perceived in the emission colour, that could be seen by naked eye under UV lamp and according to the CIE diagram represented in Figure 4.»
The contribution of the hypersensitive transition 4G5/2→6H9/2 (650 nm) for complex 1 is greater than for the others. And it color should have been more «red». However, in the photo and diagram, the emission of the complex is closer to white than the others, which means that the contribution of luminescence, which the authors associate with the ligand environment in the region up to 550 nm, plays a greater role, see Figure 3(1). A full spectrum with the region 400-550 nm should be provided to explain the peculiarities of luminescence.
The UV -Visible spectra were recorded over the range from 250-800 nm, but figures were not shown and only 500-800 nm were illustrated in figure 3.
«the magnetic dipole allowed transition 4G5/2→6H7/2 is taken as a reference, and it splits to a maximum of J+1/2 Stark components for compounds 1-4 according to symmetries lower than cubic for 280 J half-integer values»
The splitting is usually given for the level, not for the transition. In the spectrum, one can see less than the maximum number of splitting lines components ( maximum number of components is equal to 3x4). It is worth constructing an assumption from the opposite, to show that the number of observed components is greater than in the case of a cubic one. For a cubic type with a half-integer J, the splitting will be: J=1/2,3/2 -> 1; J=5/2 -> 2; J=7/2,9/2 -> 3 [Please, see B. G. Wybourne, Spectroscopic Properties of Rare Earths, John Wiley, 1965 and 10.1016/j.dyepig.2020.108558]
This section was completely changed and modified (pages 14 & 15)
"to the ground state 4GJ, in the visible range takes place"
It should be 6HJ
Page 16, Figure 5
The luminescence decay data are commonly presented in a semi-logarithmic scale. This scale in much convenient for the decay analysis. Insufficient data collection time, the deviations from monoexponential decay law, etc can be easily detected on semi-logarithmic plots. Please, present all data in this scale along with the results of their fitting. Now it is not clear if the kinetics are really monoexponential. For details, please, see for example, 10.1016/j.saa.2019.117503.
The authors claim that the 4G7/2 and 4F3/2 levels do not participate in the luminescence of the ion, since nonradiative relaxation immediately passes from them to 4G5/2. But if this statement was made, it should be confirmed by kinetic measurements. Quite possible, that after careful analysis the kinetic decays may have a two-exponential character. Moreover, there is a weak transition from the 4F3/2 level, and this fact does not match the initial statement.
Please see p-16, This was fixed after modifying this section.
Reviewer #2
Comments and Suggestions for Authors
The manuscript (MS) entitled «Magnetic and Luminescence Properties of 8-Coordinated Pyridyl Adducts of Samarium(III) Complexes Containing 4,4,4-Trifluoro-1-(naphthalen-2-yl)-1,3-butanedionate » by Franz A. Mautner et al. is devoted to a synthesis of series of Sm3+ complexes with 4,4,4-trifluoro-1-(naphthalen-2-yl)-1,3-butanedionate and different bipyridines as ancillary ligands and investigation of their structure, photophysical and magnetic properties. In general, the article might be interesting for the readership of the Journal. To my opinion, this MS need to be significantly improved before resubmission.
Firstly, the introduction part should be revised completely. The discussion about general fields of Sm application should be removed and focused on the Sm3+ diketonates and their properties. Since 4,4,4-trifluoro-1-(naphthalen-2-yl)-1,3-butanedione is rather a popular ligand for preparation of coordination compounds of lanthanides, and particular, Sm3+ some previously obtained results should be discussed ( please, see for example,10.1021/ja073970w, 10.1021/ic8020782, 10.1016/0022-328X(94)05081-L). A short review of coordination ability of 4,4,4-trifluoro-1-(naphthalen-2-yl)-1,3-butanedione as well as a detailed description of its photophysical properties can be found in ref. 10.1016/j.dyepig.2021.109701.
The reviewer is right, the first five lines in the introduction were deleted together with the reference in this part and the focus was on some of the applications of lanthanides and their coordination properties with emphasize on the beta-diketonate ligands.
Page 3 and the first two references indicated by the reviewer were inserted (52 & 53)
«…samarium(III) compounds exhibit orange/red light emission [2-10], but other lights
are rare [10-13].»
This statement is vague: the emission of Sm3+ is originated from distinct f-f transition, and therefore spectral lines wavelengths are strictly determined. Different colors can be obtained only if additional to Sm emissions bands are admixing to the resulting emission (e.g. ligand luminescence, etc). Please, reformulate or delete this paragraph. Thus, references 10-13 are not relevant. Reference 6 is not relevant also, since non-luminescent complexes of divalent Sm are described there. The other references in the Introduction thus must be carefully checked for relevancy.
Page 2, 64-66
«…this may lead to tuning the position of the ligands’ triplet levels to give good energy transfer between the diketonato ligands and the lanthanide ion [44-46] through reducing nonradiative quenching of lanthanide luminescence [44-50]»
The value of energy of triplet level and nonradiative relaxation processes ( not quenching, quenching cannot be « nonradiative» !) are two independent factors, which can affected on the efficiency of the luminescence. Please, see for example, ref. 39 for details. This part should be revised.
Ref. 38 & 39
«where the resulting coordinated β‐diketonates act as efficient “antenna ligands” 59
for lanthanides emitting in the UV, visible and NIR region [22-43]. »
This part was revised and UV region was deleted , ref 21-42
No complexes of lanthanides with organic ligands, emitting in the UV region are known up to date. The only suitable UV-emitting ion, Gd3+ cannot be sensitized with any organic antenna due to the very high energy of the corresponding resonant level of Gd3+.
Thank you for this important point, sentence was revised (p-, 2nd line), Ref 38
it should be solid-state InGaAs detector, not a «solid indium/gallium/arsenic detector», since InGaAs is a compound, a semiconductor, not a mixture of metals.
line 121 « Instrument in the phosphorescence mode using a 450 W xenon pulsed lamp (1.5 ns pulse)» Please, check. As a rule, Fluorolog 3 instrument is equipped by 60W xenon pulsed lamp with a typical pulse duration of 60-80 microseconds. This time is automatically subtracted from overall decay time by setting of a «delay» parameter in the FluoroEssence software ( check the instrument’s manual).
This was fixed, page 6, line 7
The elemental analysis data must be presented with two decimal points ( e.g. N 2.5 7%, not N 2.6 %).
These were fixed, pages 8 & 9.
«an intense broad band over the 350-400 nm region, indicating the same 235 modes of O/N chelation.»
UV-vis absorption spectra are not really sensitive to the mode of coordination, and line shape mainly depends upon pi-pi and n-pi transitions in the ligands. They are not suitable for the determination of the coordination model, incontrast with luminescent spectra.
We absolutely agree with the referee in this statement; therefore the sentence was revised (p-11, first two lines in section 3.3.)
«Ratio values of 6.25, 4.52, 4.62 and 4.17 were determined in the 1-4 compounds, respectively.»
In which units and these integrals were calculated? One must use energy units to calculate integrals correctly. Consequently, spectra must be presented in energy units first ( e.g. cm-1) to calculate correct integrals. At which temperature data were collected – the integral values for room temperature and 77K may be significantly different.
Units of energy were used to calculate these ratios, which of course have no units (p-13, last paragraph).
«The difference in the hypersensitive band intensity of 1-4 compounds, is 270 also perceived in the emission colour, that could be seen by naked eye under UV lamp and according to the CIE diagram represented in Figure 4.»
The contribution of the hypersensitive transition 4G5/2→6H9/2 (650 nm) for complex 1 is greater than for the others. And it color should have been more «red». However, in the photo and diagram, the emission of the complex is closer to white than the others, which means that the contribution of luminescence, which the authors associate with the ligand environment in the region up to 550 nm, plays a greater role, see Figure 3(1). A full spectrum with the region 400-550 nm should be provided to explain the peculiarities of luminescence.
The UV -Visible spectra were recorded over the range from 250-800 nm, but figures were not shown and only 500-800 nm were illustrated in figure 3.
«the magnetic dipole allowed transition 4G5/2→6H7/2 is taken as a reference, and it splits to a maximum of J+1/2 Stark components for compounds 1-4 according to symmetries lower than cubic for 280 J half-integer values»
The splitting is usually given for the level, not for the transition. In the spectrum, one can see less than the maximum number of splitting lines components ( maximum number of components is equal to 3x4). It is worth constructing an assumption from the opposite, to show that the number of observed components is greater than in the case of a cubic one. For a cubic type with a half-integer J, the splitting will be: J=1/2,3/2 -> 1; J=5/2 -> 2; J=7/2,9/2 -> 3 [Please, see B. G. Wybourne, Spectroscopic Properties of Rare Earths, John Wiley, 1965 and 10.1016/j.dyepig.2020.108558]
This section was completely changed and modified (pages 14 & 15)
"to the ground state 4GJ, in the visible range takes place"
It should be 6HJ
Page 16, Figure 5
The luminescence decay data are commonly presented in a semi-logarithmic scale. This scale in much convenient for the decay analysis. Insufficient data collection time, the deviations from monoexponential decay law, etc can be easily detected on semi-logarithmic plots. Please, present all data in this scale along with the results of their fitting. Now it is not clear if the kinetics are really monoexponential. For details, please, see for example, 10.1016/j.saa.2019.117503.
The authors claim that the 4G7/2 and 4F3/2 levels do not participate in the luminescence of the ion, since nonradiative relaxation immediately passes from them to 4G5/2. But if this statement was made, it should be confirmed by kinetic measurements. Quite possible, that after careful analysis the kinetic decays may have a two-exponential character. Moreover, there is a weak transition from the 4F3/2 level, and this fact does not match the initial statement.
Please see p-16, This was fixed after modifying this section.
Author Response File: Author Response.docx
Reviewer 3 Report
The authors reported the X-ray crystal structure, luminescence and magnetic measurements of the four Sm3+ complexes with three nta ligands. The paper cited many good references, which made it very informative. However, the system itself is not new. The similar systems with Eu3+ and Gd3+ metals and three nta ligands have been reported by the other authors. (J. A. Fernandes et al., Eur J. Inorg. Chem. 3913-3919 (2004); J. Luminescence 113, 50-63 (2005). ) It may be a good manner to share the systems with the other researchers.
Ref. 59 should be "Coord. Chem. Rev. 249" instead of "Chem. Soc. Rev."
Ln3+ also binds with S-ligands. How is this fact interpreted by the HSAB concept?
Author Response
Reviewer #3
Comments and Suggestions for Authors
The authors reported the X-ray crystal structure, luminescence and magnetic measurements of the four Sm3+ complexes with three nta ligands. The paper cited many good references, which made it very informative. However, the system itself is not new. The similar systems with Eu3+ and Gd3+ metals and three nta ligands have been reported by the other authors. (J. A. Fernandes et al., Eur J. Inorg. Chem. 3913-3919 (2004); J. Luminescence 113, 50-63 (2005). ) It may be a good manner to share the systems with the other researchers.
Ref. 59 should be "Coord. Chem. Rev. 249" instead of "Chem. Soc. Rev."
Thank you, this was corrected
Ln3+ also binds with S-ligands. How is this fact interpreted by the HSAB concept?
This is true but with respect to stability of the O-donor ligands with the Ln(III) ions are more stable than the corresponding S-donors with Ln(III) ions but both can be formed.
Author Response File: Author Response.docx
Reviewer 4 Report
This is a study on the synthesis, structure, and properties of a series of Sm(III) polypyridyl complexes with beta-diketonates. Authors report crystal structures, luminescence spectroscopy and static magnetic properties for four new synthesized derivatives. The subject is of interest for Magnetochemistry and as a whole the study is well conducted. There are however some major revisions to be undertaken before publication can be granted.
- page 6, l.223-225 The meaning of the numbers in parenthesis in the discussion of SHAPE results is unclear to me. Further, for 2 only three values are given, while they are discussing 4 polyhedra. These results should be given in tabulated form in main text to better appreciate them.
- Since they have 77 K luminescence spectra for all the complexes, on which they observe a well resolved structure for the 6H5/2, authors should provide the energy of the three observed lines, so that the CF splitting of the ground multiplet is known. In general term, energies of the assigned levels should be given in detail, since this is a piece of information on which further studies might build on (e.g. ab initio calculations of these complexes).
- The energy separations among the energy barycenters different 6H multiplets should also be provided, since these are strictly related to the effective spin-orbit coupling active in these systems. In turn, this is determining the magnetic properties of these complexes (see below).
- The discussion on the static magnetic properties is not correct and might be misleading for a non-expert in the field. The reason for the linear increase of chiT for Sm(III) complexes is not the population of excited multiplets (which is quite low even at room temperature) as stated by the authors, but the dominant temperature independent paramagnetism. Since chi is constant with temperature, chit grows linearly. The same reason can be given for the linear behaviour of M with H, since TIP is a perturbative effect linear with field. Note that TIP is particularly strong in Sm(III) (and Eu(III)), because the energy difference between ground and excited state (i.e. different s-o coupled states arising from 6H) is small compared to other Ln(III) systems. Autors should use the analytic expression reported on Kahn’s book, p. 50, to obtain some more defined information on the energy structure of these systems and to correlate them with those derived by luminescence spectra. In the same chapter they may also find a more extended explanation of the points I outlined above.
Only after these corrections have been made the article can be accepted for publication.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Reviewer 5 Report
The article "Magnetic and luminescent properties of 8-coordinated pyridyl adducts of samarium(III) complexes containing 4,4,4-Trifluoro-1-(naphthalene-2-yl)-1,3-butanedionate" is an attractive article where both the characterization of coordination complexes and the determination of properties are presented in a very concise way. The photoluminescent properties section (and associated discussion on it), in my opinion, gives highlights the relevance of the article. An appropriate Supplementary Material is delivered and broadly supports the work’s comprehension.
Nevertheless, I suggest the following corrections to further improvement of the article before publication:
1-Line 52 of the MS: It is worth specifying the meaning of the “HSAB concept,”; e.g., in brackets.
2-Lines 70-73 of the MS: please, rewrite this hefty sentence; I guess any verb is missing.
3-Line 95 of the MS: Which temperature-control module is used in the APEX CCD Diffractometer?
4-In Lines 104 and 105, authors note a partial disorder on -CF3 group in compound number 2. After reading the MS, no further reference to this structural factor is underlined. Is it not worth to take attention to this? Given this remarkable difference in contrast with the rest of the compounds, I think it is worth discussing something: luminescence-related features or unexpected consequences in solving structure...
5-In Table 1, unities of m and Dcalc include superscripts with large sizes. Please, diminish the size of them.
6-The sentence in Lines 134 and 135 should be rewritten for clarity.
7-In Line 158, remove one of both consecutive “...and allowed...”.
8-In Line 220, “CShM” is stated. This acronym is referred to as the “Continuous Shape Measure” theory (underscored above, in Line 217). It is worth relating both expressions by clarifying in brackets the meaning of CShM.
9-In Line 240, the word “Excited” should be replaced by “excited” (the first letter in lower case). Indeed, in this sentence, you state that Figure 3 shows the emission spectra at 77 K only for NIR; but, viewing that figure, the 77 K-emission spectra for visible is also inserted. I suggest rephrasing the sentence (Lines 240 and 241).
10-Sm is the symbol of samarium. Please, correct the name of the element in Lines 325 and 328.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Reviewer 6 Report
This work by Mautner et al. examines the magnetic and luminescence properties of four samarium complexes from powder samples. The results are of interest in view of their properties.
It is a well written and technically solid manuscript well worth publishing in Magnetochemistry. I feel this work can be accepted for publication provided the following, relatively minor corrections, are completed:
- Please, indicate the reference where the Pascal constants were taken from (line 90).
- Is there some kind of typo on the names of the compounds when the synthesis of the complexes is described? on the subheadings of 2.4 the names of the compounds have a point inside the brackets.
- Figures S1-S4. Line 187. Their purity was checked by PXRD powder diffraction: there is no need to repeat powder and diffraction that are already on PXRD. A comparison of the experimental data with a simulated powder pattern was performed but, which program was used to generate the simulted pattern? Mercury? Please explain. I would recomend using a profile fit to confirm the space group obtained by single crystal XRD.
Author Response
Reviewer #6
Comments and Suggestions for Authors
This work by Mautner et al. examines the magnetic and luminescence properties of four samarium complexes from powder samples. The results are of interest in view of their properties.
It is a well written and technically solid manuscript well worth publishing in Magnetochemistry. I feel this work can be accepted for publication provided the following, relatively minor corrections, are completed:
- Please, indicate the reference where the Pascal constants were taken from (line 90).
Thank, you the reference was inserted # 55
- Is there some kind of typo on the names of the compounds when the synthesis of the complexes is described? on the subheadings of 2.4 the names of the compounds have a point inside the brackets.
These were fixed.
- Figures S1-S4. Line 187. Their purity was checked by PXRD powder diffraction: there is no need to repeat powder and diffraction that are already on PXRD. A comparison of the experimental data with a simulated powder pattern was performed but, which program was used to generate the simulted pattern? Mercury? Please explain. I would recomend using a profile fit to confirm the space group obtained by single crystal XRD.
Yes, we agree with the reviewer on both points the PXRD was fixed as recommended and program used for fitting was given (Ref 54).
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The authors took into account most of my comments. Nonetheless, the luminescent part shoud be improved. The discussion about energy transfer in complexes must be supported by data concerning triplet and singlet levels energy, since the excitation of Sm3+ is indirect ( through the ligands). The detailed photophysical data of fluorinated naphthalene ligands can be found in the article 10.1016/j.dyepig.2021.109701. Diffusion reflectance spectra for solid samples and absorption spectra in the solutions also can be helpful for the determination of singlet level energy. Also, it would be better to present kinetic data and corresponding fits in the Figure 5 in the semilogarithmic scale, in order to prove the monoexponential nature of the decays.
Reviewer 4 Report
This revised version addresses correctly three of my previous four remarks. However, it still contains severe errors in the discussion of the magnetic data, which absolutely needs corrections. Here are the points to correct:
- Apparently, authors had some issues with using the correct units in the Equation reported in Kahn’s book. Indeed, Figure 3.7 in that book is obtained by setting lambda = 200 cm-1. With a lambda value of ca. 340 cm-1 obtained by luminescence, the calculated curve should not be too different from that one, then clearly dismissing the hypothesis of 10^34 cm-1 value for lambda reported by the authors. I urge authors to correctly implement the fit by using eq. 3.6.11 in the Kahn’s book, at least to find the predicted value of chiT at room temperature by using the experimentally determined lambda value. The calculated curves obtained by using the spectroscopically determined lambda value must be included as well.
- The sentence “The found χMT values at 300 K are due to the population of the low lying first excited state 6H7/2 at room temperature [79]”, is not correct, as I mentioned in my previous report, and should be changed. Indeed, the population of the excited J=7/2 multiplet is clearly very small at room temperature, so that the larger chiT value is essentially due the second-order contribution (so called Van-Vleck contribution). Said differently, the presence of excited states not too far in energy from the ground state add a significant temperature-independent contribution to the magnetic susceptibility which is the cause of the observed linear behaviour of chiT vs T. This point must be corrected.
- The sentences: “From the energy separation between (…) are 342, 351, 381 and 364 cm-1 for 1-4, respectively.“ must be moved at the end of the discussion of the spectroscopy results (i.e. after “tabulated as 1000 cm-1, in good accordance with the calculated values for 1-4”). Indeed, the spin orbit coupling constant is obtained by spectroscopic data, not magnetic analysis.
- The sentence “Taking into account the 4f5 ground configuration of the Sm(III) ion the value of the saturated magnetization should be > 5 NµB” is wrong. I do not understand where they obtain the 5 NµB value from. Indeed, for a J=5/2, gJ=2/7 a theoretical saturation value of 5/7 NµB is expected (Msat=NmuB*gJ*J). This is still much larger than the values observed, a phenomenon which authors correctly attribute to CF effects.
I want to stress that, despite being minor revisions (i.e they do not require much work) these are absolutely unavoidable corrections. In the absence of these corrections (with particular focus on the first one), the paper cannot be accepted, even more so for a journal as Magnetochemistry devoted to the analysis of magnetic behaviour of molecules and materials.
