The Role of Substitution in the Apex Position of the Bent-Core on Mesomorphic Properties of New Series of Liquid Crystalline Materials
, Damian Pociecha 3 and Michal Kohout 1,*Round 1
Reviewer 1 Report
This is a really good paper which deserves publication in Crystals. This manuscript explores the effect of apex substitution in bent-core liquid crystals. The paper is very well written, contains a balanced introduction, and is on an area of significant interest.
Chemical materials have been subjected to satisfactory analysis, and reference to prior synthesis has been made.
The majority of substituents are found to be detrimental to the mesomorphic state, and the authors attribute this to steric effects. The mesomorphic properties of liquid crystalline materials are characterised in significant detail by a wide range of methods. Ultimately, this paper makes a notable contribution to efforts to understand the link between molecular structure and properties, and should be published.
minor comments
I think some additional citations are warranted to prior work on BCLCs with apex substitution (-5 position); e.g. 10.1080/02678290500473586.
BCLCs, albeit not apex substituted, have been shown to induce polar splaying nematic phases in mixtures (10.1039/C9SM02143D) and this be relavent to the introduction, where "polar and chiral order" is mentioned.
In the synthetic portion, where the authors have prepared homologous materials (e.g. 4-[4-(Decyloxy)benzoyloxy]phenyl 3-(tert-butyldimethylsilyloxy)-5-chlorobenzoate) only a yield and MP are included. Where these are novel compounds, such as the example I have chosen, spectral data should also be provided.
Author Response
We would like to thank the reviewer for checking the overall quality of the manuscript a for the suggestions to improve it.
We have added the suggested references on substituted bent-core liquid crystals and their polar behaviour. The references are highlighted yellow.
As for the spectroscopic data of intermediates, we have not added this information for the other intermediates. The spectra of homologues in a series do not differ; the only difference is the integral value of a broad singlet at about 1.2-1.6 ppm, which represents methylene units in the terminal alkyl chain. This note has also been added into the manuscript.
Reviewer 2 Report
The article presents the synthesis and characterisation of new bent-core compounds based on 3-hydroxybenzoic acid, lateraly substituted with different substituents, in continuation to previous studies on this class of compounds. Compounds containing F as substitutent resulted liquid crystalline and showed columnar B1 phases and respectively lamellar SmCaPa phases. This is a highly interesting subject of research, due to the appealing properties of bent-core liquid crystals for practical applications. There is an appreciable organic synthesis, the compounds are structurally well characterized; their mesomorphic and dielectric properties were accurately investigated. Therefore, the article should be published, after one minor clarification:
- the authors claim in the article text that in Figure 3 a change of birefringence under applied electric field occurs; however the figure caption does not clearly explain it. It should be indicated the polarity of the applied filed and the change in birefringence.
Author Response
We would like to thank the reviewer for careful reading of the manuscript.
We have modified the caption of figure 3 to indicate the orientation of polarizers and the applied voltage used to induce the observed changes. The statement given in the text has also been modified to provide more concise information.
