Switching Ion Binding Selectivity of Thiacalix[4]arene Monocrowns at Liquid–Liquid and 2D-Confined Interfaces

Round 1

Reviewer 1 Report

In this paper the Authors tried to synthesize and study the receptor properties of a set of crown-containing thiacalixarenes. The main idea behind these efforts is to study the interaction of cations with artificial receptors and to find the unique structural features that determine selective binding within confined and pre-organized space. To do this, the Authors compare the binding properties of receptors differing in crown-ether size, lengths of alkoxy-substituent and ability to form Langmuir monolayers.

Thorough study reveals several important points: (i) at liquid-liquid interface the receptors with 5-6 crowns show the desired properties compared to 4 congeners; (ii) calixarene aggregations in some cases prevent the desired binding; (iii) at water-air interfaces the monolayer/cation interaction could be monitored by several methods, as a result a correlation between crown-size and nature of metal cation is found.

The paper deserves to be published as it is.

For the future the Referee would advise making the Conclusion part in the manuscripts 

Reviewer 2 Report

This manuscript by Muravev et al. deals with the synthesis of some thiacalix[4]arene monocrowns and their binding selectivity at liquid–liquid and 2D-confined interfaces.

The main result of this work is the switching of ion binding selectivity by going from the solution state to confined interfaces. In particular, amphiphilic type-I/II conjugates, surprisingly, extracted different metal ions. This was attributed to calixarene aggregation in salt aqueous phase and was supported by DLS measurements. A topology-varied selectivity was also evidenced for cation–monolayer interactions at air–water interface, which were monitored by surface pressure/potential measurements and UV/visible reflection–absorption spectroscopy.

The manuscript is well written and the results are fully convincing thanks to the variety of experimental techniques used, including theoretical calculations. I believe that this manuscript is suitable for publication in  Int. J. Mol. Sci. in its present form. I have only three very minor concerns that could be addressed by the authors.

• In the title, I would delete “Topology and Environment Matter:” because it creates some misunderstanding about its content, which is particularly detrimental for a multidisciplinary journal like Int. J. Mol. Sci.
• In the title of section 2.3 the word “Ligiands” should be “Ligands”.
• In the Supplementary Information the page numbers should be reported.

Author Response

This manuscript by Muravev et al. deals with the synthesis of some thiacalix[4]arene monocrowns and their binding selectivity at liquid–liquid and 2D-confined interfaces.

The main result of this work is the switching of ion binding selectivity by going from the solution state to confined interfaces. In particular, amphiphilic type-I/II conjugates, surprisingly, extracted different metal ions. This was attributed to calixarene aggregation in salt aqueous phase and was supported by DLS measurements. A topology-varied selectivity was also evidenced for cation–monolayer interactions at air–water interface, which were monitored by surface pressure/potential measurements and UV/visible reflection–absorption spectroscopy.

The manuscript is well written and the results are fully convincing thanks to the variety of experimental techniques used, including theoretical calculations. I believe that this manuscript is suitable for publication in  Int. J. Mol. Sci. in its present form. I have only three very minor concerns that could be addressed by the authors.

• In the title, I would delete “Topology and Environment Matter:” because it creates some misunderstanding about its content, which is particularly detrimental for a multidisciplinary journal like Int. J. Mol. Sci.

Deleted “Topology and Environment Matter:” from the title.

• In the title of section 2.3 the word “Ligiands” should be “Ligands”.

Corrected

• In the Supplementary Information the page numbers should be reported.

Added page number to the Supplementary Information.

 

On behalf of the co-authors, I would like to thank the Reviewer for careful reading of the manuscript text and comments.

Reviewer 3 Report

In this manuscript, the authors describe the study of metal ion complexation with conformationally varied thiacalix [4]monocrowns at the liquid-liquid interface under extraction conditions and at the air-water interface. Extensive studies were carried out using various techniques to explain the ion binding selectivity. I recommend this paper for publication in International journal of molecular sciences.

Few issues:

• all physical quantities (melting point, retention factor, wavelength..) should be written in italic
• small letter c should be used for molar concentration, it should be expressed in SI units
• in IR spectra wavenumber should be used instead of frequency

Author Response

In this manuscript, the authors describe the study of metal ion complexation with conformationally varied thiacalix [4]monocrowns at the liquid-liquid interface under extraction conditions and at the air-water interface. Extensive studies were carried out using various techniques to explain the ion binding selectivity. I recommend this paper for publication in International journal of molecular sciences.

Few issues:

• all physical quantities (melting point, retention factor, wavelength..) should be written in italic

The manuscript text was carefully revised for missing italicizing of the physical quantities and corrections were made (Sections 2.3–2.6 and 3).

• small letter c should be used for molar concentration, it should be expressed in SI units

Replaced C by c for molar concentration and standardized expression into M everywhere (in order not to confuse with SI prefix mega M).

• in IR spectra wavenumber should be used instead of frequency

Replaced ν by  in Section 3.

 

On behalf of the co-authors, I would like to thank the Reviewer for careful reading of the manuscript text and comments.