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

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

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

Chemical composition and antibacterial activity of essential oils from the medicinal plant Mentha cervina L. grown in Portugal

Mentha cervina is a medicinal plant traditionally used in Portugal in folk medicine, in different gastric disorders and inflammations of the respiratory tract. In order to validate those traditional uses, M. cervina essential oils (EOs) were characterized by GC and GC–MS and their antimicrobial activity was tested against 23 bacterial strains (including multiresistant strains). The EOs were dominated by the monoterpenes pulegone (52–75%), isomenthone (8–24%), limonene (4–6%), and menthone (1–2%). The antibacterial activity of these EOs was compared to that of the main components standards. The most effective antibacterial activity was expressed by the EOs against the Gram-negative bacteria, Escherichia coli and Acinetobacter baumanni, with MIC values of 1 mg/ml. The EOs complex mixtures were more active than the individual aromatic components supporting the hypothesis that the EOs antibacterial activity is a function of the synergistic effect of their different aromatic components. These results show the potential role of M. cervina EOs as antibacterial agents and validate the traditional use of this plant

Invited review: Reliability computation from the animal model era to the single-step genomic model era

The calculation of exact reliabilities involving the inversion of mixed model equations poses a heavy computational challenge when the system of equations is large. This has prompted the development of different approximation methods. We give an overview of the various methods and computational approaches in calculating reliability from the era before the animal model to the era of single-step genomic models. The different methods are discussed in terms of modeling, development, and applicability in large dairy cattle populations. The paper also describes the problems faced in reliability computation. Many details dispersed throughout the literature are presented in this paper. It is clear that a universal solution applicable to every model and input data may not be possible, but we point out several efficient and accurate algorithms developed recently for a variety of very large genomic evaluations

Valuing nature’s contributions to people: the IPBES approach

Nature is perceived and valued in starkly different and often conflicting ways. This paper presents the rationale for the inclusive valuation of nature’s contributions to people (NCP) in decision making, as well as broad methodological steps for doing so. While developed within the context of the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES), this approach is more widely applicable to initiatives at the knowledge–policy interface, which require a pluralistic approach to recognizing the diversity of values. We argue that transformative practices aiming at sustainable futures would benefit from embracing such diversity, which require recognizing and addressing power relationships across stakeholder groups that hold different values on human nature-relations and NCP