Novel functional [4]helicenes through a photooxidation pathway. Investigation of the absorption and fluorescence in solution

Novel functional [4]helicenes have been designed and synthesized, in 54%–72% overall yields, through an operational and simple two-step photochemical approach starting from various p-substituted phenylacetonitriles, and were characterized by NMR ($^{1}$H, $^{13}$C, and COSY) and FT-IR spectroscopies. UV–Vis absorption properties of these tetracyclic ${\pi }$-conjugated systems have been experimentally investigated in various solvents and their optical gap energy was estimated to be less than 3.28 eV. The photoluminescence properties of these molecules have been evaluated in solutions and an emission in the blue region of the visible spectrum was noted. The obtained results seem encouraging for the examination of such compounds as promising materials for optoelectronic applications

7-Cyano-15-methoxy[6]helicene through a photochemical pathway and investigation of its chiroptical and photophysical properties

7-Cyano-15-methoxy[6]helicene was synthesized, in 54% overall yield, through a short photochemical procedure including mild conditions and inexpensive reagents. The desired helical hexacyclic framework was characterized by $^{1}\mathrm{H}$ and $^{13}\mathrm{C}$ NMR and mass spectroscopies. Single crystals of the helicene were also obtained and an X-ray diffraction analysis is presented. Enantiomers of the helicene were obtained in 100% $ee$ after separation by chiral HPLC and their chiroptical properties were experimentally investigated from optical rotatory dispersion and electronic circular dichroism (ECD). UV–Vis absorption and fluorescence properties of the helicene were evaluated in solutions and a strong emission was noted in the blue region of the visible spectrum . Its electrochemical behavior was also experimentally examined and HOMO and LUMO energy levels were estimated, showing an electrochemical band gap of 2.11 eV. The results obtained herein are helpful to explain the interest of cyano and methoxy groups in making the new material a good candidate to be used in optoelectronic applications

Novel functional [4]helicenes through a photooxidation pathway. Investigation of the absorption and fluorescence in solution

Novel functional [4]helicenes have been designed and synthesized, in 54%–72% overall yields, through an operational and simple two-step photochemical approach starting from various p-substituted phenylacetonitriles, and were characterized by NMR ($^{1}$H, $^{13}$C, and COSY) and FT-IR spectroscopies. UV–Vis absorption properties of these tetracyclic ${\pi }$-conjugated systems have been experimentally investigated in various solvents and their optical gap energy was estimated to be less than 3.28 eV. The photoluminescence properties of these molecules have been evaluated in solutions and an emission in the blue region of the visible spectrum was noted. The obtained results seem encouraging for the examination of such compounds as promising materials for optoelectronic applications

7-Cyano-15-methoxy[6]helicene through a photochemical pathway and investigation of its chiroptical and photophysical properties

7-Cyano-15-methoxy[6]helicene was synthesized, in 54% overall yield, through a short photochemical procedure including mild conditions and inexpensive reagents. The desired helical hexacyclic framework was characterized by $^{1}\mathrm{H}$ and $^{13}\mathrm{C}$ NMR and mass spectroscopies. Single crystals of the helicene were also obtained and an X-ray diffraction analysis is presented. Enantiomers of the helicene were obtained in 100% $ee$ after separation by chiral HPLC and their chiroptical properties were experimentally investigated from optical rotatory dispersion and electronic circular dichroism (ECD). UV–Vis absorption and fluorescence properties of the helicene were evaluated in solutions and a strong emission was noted in the blue region of the visible spectrum . Its electrochemical behavior was also experimentally examined and HOMO and LUMO energy levels were estimated, showing an electrochemical band gap of 2.11 eV. The results obtained herein are helpful to explain the interest of cyano and methoxy groups in making the new material a good candidate to be used in optoelectronic applications

Synthesis and chiroptical properties of organometallic complexes of helicenic N-heterocyclic carbenes

International audienceNovel [4, 6]helicenes (4a,b) bearing a fused imidazolium unit have been prepared from [4, 6]helicene-2,3-di-n-propyl-amines 3a,b. The in situ formation of N-heterocyclic carbene (NHC) derivatives followed by their complexation to iridium(I) or rhodium(I) gave access to complexes 1a, 1'a, and 1b, containing mono-coordinated helicene-NHC, chloro and COD (COD = 1,5-cyclooctadiene) ligands. Ir and Rh complexes 1a and 1'a were characterized by X-ray crystallography. HPLC and NMR analyses showed that Ir(I) complex 1b existed as a mixture of two diastereomeric complexes corresponding to enantiomeric pairs M-(-)/P-(+)-1b and M-(-)/P-(+)-1b which differ by the position of COD through space. The chiroptical properties (electronic circular dichroism and optical rotation) of the four stereoisomers were measured. These complexes were also tested as catalysts in a transfer hydrogenation reaction

HLA Class III: A susceptibility region to systemic lupus erythematosus in Tunisian population

<div><p>Background and objectives</p><p>Short tandem repeats (STR) are usually used as informative polymorphic markers for genetic mapping and for disease susceptibility analysis. The involvement of these microsatellite markers localized in the MHC region was reported in many auto-immune diseases.</p><p>In this study we analyzed for the first time eight polymorphisms of microsatellite loci at the HLA region: D6S291, D6S273, TNFa, b and c, MICA, D6S265 and D6S276, in Tunisian systemic lupus erythematosus (SLE) patients.</p><p>Materials and methods</p><p>We performed a case control study in which the microsatellite loci were amplified using specific primers labeled with NED, VIC, PET or 6-FAM and analyzed using GeneScan software 3.7. For the statistical analysis, we used SPSS software and we performed a sub-haplotype scoring test using the haplo.stats software developed in the R language.</p><p>Results</p><p>We found that two mean associated regions existed; the most statistically significant encompassed the 3 TNF markers (p = 0.0003, OR = 19.34); the latter covered the DR region. In fact, when scoring haplotypes in 3 marker- sliding windows, the p value increased as we moved away from the TNF region and decreased again when we approached the DRB1 locus. We also established for the first time the negative association between alleles of D6S291 and SLE. The majority of clinical and serological correlations were noted with TNF alleles.</p><p>Conclusion</p><p>Our results confirm the association between TNF and DRB1 polymorphisms and SLE. The association between alleles of D6S291 and SLE needs however to be verified by the analysis of other markers beyond this region.</p></div

Clinical and immunological manifestations in our patients.

<p>Clinical and immunological manifestations in our patients.</p

Three-marker window haplotype analysis.

<p>Three-marker window haplotype analysis.</p

Characteristics of studied STR.

<p>Characteristics of studied STR.</p