Dataset Information

Synthesis of aminyl biradicals by base-induced Csp³-Csp³ coupling of cationic azo dyes.

ABSTRACT: The synthesis of the industrially important polymer parylene is achieved by polymerization of p-quinodimethane (p-QDM). The polymerization is thought to proceed via a biradical p-QDM dimer, but isolation or characterization of such a biradical has remained elusive. Here, we describe the synthesis of an aza-analogue of this p-QDM dimer. The biradical is formed by base-induced dimerization of an azoimidazolium dye. Due to the presence of sterically shielded aminyl radicals instead of terminal H₂? groups, the stability of this dimer is sufficient for analyses by ESR spectroscopy and X-ray crystallography. A similar Csp³-Csp³ coupling was observed for an azotriazolium dye, suggesting that base-induced C-C coupling reactions can be realized for different types of azo dyes.

SUBMITTER: Liu Y

PROVIDER: S-EPMC6568049 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature

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Synthesis of aminyl biradicals by base-induced Csp3-Csp3 coupling of cationic azo dyes.

Liu Yizhu Y Varava Paul P Fabrizio Alberto A Eymann Léonard Y M LYM Tskhovrebov Alexander G AG Planes Ophélie Marie OM Solari Euro E Fadaei-Tirani Farzaneh F Scopelliti Rosario R Sienkiewicz Andrzej A Corminboeuf Clémence C Severin Kay K

Chemical science 20190509 22

The synthesis of the industrially important polymer parylene is achieved by polymerization of p-quinodimethane (p-QDM). The polymerization is thought to proceed via a biradical p-QDM dimer, but isolation or characterization of such a biradical has remained elusive. Here, we describe the synthesis of an aza-analogue of this p-QDM dimer. The biradical is formed by base-induced dimerization of an azoimidazolium dye. Due to the presence of sterically shielded aminy ...[more]

PMID: 31293757

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Project description:Reduction of Methyl Red (MR) and Orange II (Or II) by 26 human skin bacterial species was monitored by a rapid spectrophotometric assay. The analysis indicated that skin bacteria, representing the genera Staphylococcus, Corynebacterium, Micrococcus, Dermacoccus and Kocuria, were able to reduce MR by 74-100 % in 24 h, with only three species unable to reduce completely the dye in that time. Among the species tested, only Corynebacterium xerosis was unable to reduce Or II to any degree by 24 h, and only Staphylococcus delphini, Staphylococcus sciuri subsp. sciuri and Pseudomonas aeruginosa were able to reduce completely this dye within 24 h. MR reduction started with early-exponential growth in Staphylococcus aureus and Staphylococcus epidermidis, and around late-exponential/early-stationary growth in P. aeruginosa. Reduction of Or II, Ponceau S and Ponceau BS started during late-exponential/early-stationary growth for all three species. Using liquid chromatography/electrospray ionization mass spectrometry analyses, MR metabolites produced by Staph. aureus, Staph. epidermidis and P. aeruginosa were identified as N,N-dimethyl-p-phenylenediamine and 2-aminobenzoic acid. Searches of available genomic and proteomic data revealed that at least four of the staphylococci in this study, Staphylococcus haemolyticus, Staph. epidermidis, Staphylococcus cohnii and Staphylococcus saprophyticus, have hypothetical genes with 77, 76, 75 and 74 % sequence identity to azo1 encoding an azoreductase from Staph. aureus and hypothetical proteins with 82, 80, 72 and 74 % identity to Azo1, respectively. In addition, Staphylococcus capitis has a protein with 79 % identity to Azo1. Western analysis detected proteins similar to Azo1 in all the staphylococci tested, except Staph. delphini, Staph. sciuri subsp. sciuri and Staphylococcus auricularis. The data presented in this report will be useful in the risk assessment process for evaluation of public exposure to products containing these dyes.

Dataset Information

Synthesis of aminyl biradicals by base-induced Csp³-Csp³ coupling of cationic azo dyes.

Publications

Synthesis of aminyl biradicals by base-induced Csp<sup>3</sup>-Csp<sup>3</sup> coupling of cationic azo dyes.

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