10 research outputs found
Recent advances in organic synthesis using light-mediated n-heterocyclic carbene catalysis
The combination of photocatalysis with other ground state catalytic systems have attracted much attention recently due to the enormous synthetic potential offered by a dual activation mode. The use of N-heterocyclic carbene (NHC) as organocatalysts emerged as an important synthetic tool. Its ability to harness umpolung reactivity by the formation of the Breslow intermediate has been employed in the synthesis of thousands of biologically important compounds. However, the available coupling partners are relatively restricted, and its combination with other catalytic systems might improve its synthetic versatility. Thus, merging photoredox and N-heterocyclic carbene (NHC) catalysis has emerged recently as a powerful strategy to develop new transformations and give access to a whole new branch of synthetic possibilities. This review compiles the NHC catalyzed methods mediated by light, either in the presence or absence of an external photocatalyst, that have been described so far, and aims to give an accurate overview of the potential of this activation modeL.M. acknowledges the Autonomous Community of Madrid (CAM)
for the financial support (PEJD-2019-PRE/AMB-16640 and SI1/PJI/
2019-00237) and for an “Atracción de Talento Investigador”
contract (2017-T2/AMB-5037
Control of calcium phosphate particles-mediated acute inflammation: in vitro and in vivo evidence of anti-PDE4 molecules efficiency.
International audienc
VizieR Online Data Catalog: TOI-178 six transiting planets (Leleu+, 2021)
Raw and detrended data from CHEOPS, NGTS, SPECULOOS and TESS; raw data from ESPRESSO. (15 data files)
VizieR Online Data Catalog: TOI-178 six transiting planets (Leleu+, 2021)
Raw and detrended data from CHEOPS, NGTS, SPECULOOS and TESS; raw data from ESPRESSO. (15 data files)
Six transiting planets and a chain of Laplace resonances in TOI-178
Determining the architecture of multi-planetary systems is one of the cornerstones of understanding planet formation and evolution. Resonant systems are especially important as the fragility of their orbital configuration ensures that no significant scattering or collisional event has taken place since the earliest formation phase when the parent protoplanetary disc was still present. In this context, TOI-178 has been the subject of particular attention since the first TESS observations hinted at the possible presence of a near 2:3:3 resonant chain. Here we report the results of observations from CHEOPS, ESPRESSO, NGTS, and SPECULOOS with the aim of deciphering the peculiar orbital architecture of the system. We show that TOI-178 harbours at least six planets in the super-Earth to mini-Neptune regimes, with radii ranging from 1.152-0.070+0.073to 2.87-0.13+0.14Earth radii and periods of 1.91, 3.24, 6.56, 9.96, 15.23, and 20.71 days. All planets but the innermost one form a 2:4:6:9:12 chain of Laplace resonances, and the planetary densities show important variations from planet to planet, jumping from 1.02-0.23+0.28to 0.177-0.061+0.055times the Earth's density between planets c and d. Using Bayesian interior structure retrieval models, we show that the amount of gas in the planets does not vary in a monotonous way, contrary to what one would expect from simple formation and evolution models and unlike other known systems in a chain of Laplace resonances. The brightness of TOI-178 (H = 8.76 mag, J = 9.37 mag, V = 11.95 mag) allows for a precise characterisation of its orbital architecture as well as of the physical nature of the six presently known transiting planets it harbours. The peculiar orbital configuration and the diversity in average density among the planets in the system will enable the study of interior planetary structures and atmospheric evolution, providing important clues on the formation of super-Earths and mini-Neptunes.</p
VizieR Online Data Catalog: TOI-178 six transiting planets (Leleu+, 2021)
Raw and detrended data from CHEOPS, NGTS, SPECULOOS and TESS; raw data from ESPRESSO. (15 data files)
Six transiting planets and a chain of Laplace resonances in TOI-178
Determining the architecture of multi-planetary systems is one of the
cornerstones of understanding planet formation and evolution. Resonant systems
are especially important as the fragility of their orbital configuration
ensures that no significant scattering or collisional event has taken place
since the earliest formation phase when the parent protoplanetary disc was
still present. In this context, TOI-178 has been the subject of particular
attention since the first TESS observations hinted at a 2:3:3 resonant chain.
Here we report the results of observations from CHEOPS, ESPRESSO, NGTS, and
SPECULOOS with the aim of deciphering the peculiar orbital architecture of the
system. We show that TOI-178 harbours at least six planets in the super-Earth
to mini-Neptune regimes, with radii ranging from 1.152(-0.070/+0.073) to
2.87(-0.13/+0.14) Earth radii and periods of 1.91, 3.24, 6.56, 9.96, 15.23, and
20.71 days. All planets but the innermost one form a 2:4:6:9:12 chain of
Laplace resonances, and the planetary densities show important variations from
planet to planet, jumping from 1.02(+0.28/-0.23) to 0.177(+0.055/-0.061) times
the Earth's density between planets c and d. Using Bayesian interior structure
retrieval models, we show that the amount of gas in the planets does not vary
in a monotonous way, contrary to what one would expect from simple formation
and evolution models and unlike other known systems in a chain of Laplace
resonances. The brightness of TOI-178 allows for a precise characterisation of
its orbital architecture as well as of the physical nature of the six presently
known transiting planets it harbours. The peculiar orbital configuration and
the diversity in average density among the planets in the system will enable
the study of interior planetary structures and atmospheric evolution, providing
important clues on the formation of super-Earths and mini-Neptunes