4,4’-(Thiophene-2,5-diylbis(ethyne-2,1-diyl))bis(1-methyl-1-pyridinium) Iodide
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
The manuscript by L. Romagnoli et al. focuses on the synthesis of new modified viologen in which two pyridinium units are linked via functionalized with thiophene in the central core and two acetylene bonds. The title compound was prepared by simple methylation of known precursor (compound 3; JACS 2006, 128, 2806), which was prepared in a bit different extended way by two Sonogoashira copulings as key steps. The target compound and intermediates were characterized by means of spectroscopy and the provided data cause no doubts. Thus, the paper can be considered for publication after following corrections.
Major correction:
In the context of general properties/applications of such viologen compounds, analysis of electrochemical behaviour is strongly recommended. To my opinion, the manuscript should be supplemented by CV measurement along with brief comment on that.
Furthermore, melting points for all solid materials should be provided. Also, in the experimental part the MS result for the final compound (di-cation of the final salt should be visible under mild ESI method) should be presented.
Minor corrections:
- page 2, line 48. Add ‘T’ to read ‘This compound …’
- please add appropriate citations to all known compounds reported in ‘Materials and Methods’
Author Response
Response to reviewer comments.
As regards the electrochemical characterization, we performed the cyclic voltammetry of the title compound 4, thus measuring the redox potential. Main differences with methyl viologen CV were highlighted and briefly commented.
Melting point of the title compound 4 was reported. As regards the melting points of the intermediates, we totally converted them during the synthesis. Thus, unfortunately they were not available for mp measurements.
The ESI MS spectrum of 4 was achieved, showing only the proton adduct of the salt (dication with two I-).
The minor revision was done according the reviewer requests.
On the line 48, tthe "T" was added.
We added proper citations in Materials and Methods section about the literature synthesis of all the intermediates.
Round 2
Reviewer 1 Report
Comments and Suggestions for Authors
The paper is ready to go.
