Kinetic enantio-recognition of chiral viologen guests by planar-chiral porphyrin cages.

peer reviewedThe kinetic enantio-recognition of chiral viologen guests by planar-chiral porphyrin cage compounds, measured in terms of ΔΔG‡on, is determined by the planar-chirality of the host and influenced by the size, as measured by ion mobility-mass spectrometry, but not the chirality of its substituents

Hélicènes pour les commutateurs moléculaires chiraux, les matériaux magnétiques et le fullerène chiral dérivés

Dans ce travail de thèse, nous avons d'abord développé deux études basées sur des unités dites ''stilbène rigide'' qui sont connues pour s'interconvertir de manière réversible entre deux formes trans et cis grâce à la lumière. La première étude correspond à des photocommutateurs chiraux à base d'hélicènes, l'autre à des complexes photocommutables alcynyles d'or(I). Ensuite, nous avons examiné la synthèse et la caractérisation de complexes de Dy(III) à base d'hélicène-bipyridine comme nouveaux types d'aimants moléculaires (SMM) chiraux et comparé la différence des propriétés magnétiques entre les SMM racémique et énantiopurs. Enfin, nous avons développé la première utilisation de la cycloaddition réversible d'hélicènes racémiques sur le [60]fullerène et de sa rétrocycloaddition ultérieure comme une stratégie alternative efficace pour le dédoublement énantiomérique d'un hélicène-carboxaldéhyde.In this PhD work, we firstly developed two studies based on the so-called ''stiff stilbene'' units that are known to reversibly interconvert between two trans and cis forms through light. The first study corresponds to photoresponsive chiral switches based on helicenes, the other one to photoresponsive gold(I) complexes. Then, we dealt with the synthesis and characterization of helicene-bipyridine based Dy(III) complexes as novel kinds of chiral single molecule magnets (SMMs) and compared the difference of the magnetic properties between racemic and enantiopure SMMs. Finally, we developed the first use of the reversible sterodivergent cycloaddition of racemic helicenes onto [60]fullerene with its subsequent retro-cycloaddition as an efficient alternative strategy for the enantiomeric resolution of a helicene-carboxaldehyde

Reversible Stereodivergent Cycloaddition of Racemic Helicenes to [60]Fullerene: A Chiral Resolution Strategy

International audience[60]Fullerene and its rarely explored reversible covalent chemistry have been harnessed as an efficient alternative for the chiral resolution of racemates. By using only catalytic amounts of chiral agents, stereodivergent 1,3-dipolar cycloadditions of racemic helicenes onto [60]fullerene were carried out. The formed helicene/fullerene diastereomers were easily separated by conventional chromatography, and afterward, a simple catalyzed 1,3-dipolar retro-cycloaddition afforded helicene starting materials in high optical purity

Enantioselective synthesis of chiral porphyrin macrocyclic hosts and kinetic enantiorecognition of viologen guests

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Synthesis of a Helical Bilayer Nanographene

International audienceA rigid, inherently chiral bilayer nanographene has been synthesized as both the racemate and enantioenriched M isomer (with 93 % ee) in three steps from established helicenes. This folded nanographene is composed of two hexa-peri-hexabenzocoronene layers fused to a [10]helicene, with an interlayer distance of 3.6 Å as determined by X-ray crystallography. The rigidity of the helicene linker forces the layers to adopt a nearly aligned AA-stacked conformation, rarely observed in few-layer graphene. By combining the advantages of nanographenes and helicenes, we have constructed a bilayer system of 30 fused benzene rings that is also chiral, rigid, and remains soluble in common organic solvents. We present this as a molecular model system of bilayer graphene, with properties of interest in a variety of potential applications

Absolute configuration and host-guest binding of chiral porphyrin-cages by a combined chiroptical and theoretical approach

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Helicenic Complexes of Lanthanides: Influence of the f-Element on the Intersystem Crossing Efficiency and Competition between Luminescence and Oxygen Sensitization

International audienc

Kinetic enantio-recognition of chiral viologen guests by planar-chiral porphyrin cages

International audienceThe kinetic enantio-recognition of chiral viologen guests by planar-chiral porphyrin cage compounds, measured in terms of Delta Delta G double dagger on, is determined by the planar-chirality of the host and influenced by the size, as measured by ion mobility-mass spectrometry, but not the chirality of its substituents. The enantio-kinetic threading of chiral guests by chiral porphyrin hosts is determined by the planar chirality of the host and influenced by the size but not the chirality of the substituent X

Absolute configuration and host-guest binding of chiral porphyrin-cages by a combined chiroptical and theoretical approach.

Porphyrin cage-compounds are used as biomimetic models and substrate-selective catalysts in supramolecular chemistry. In this work we present the resolution of planar-chiral porphyrin cages and the determination of their absolute configuration by vibrational circular dichroism in combination with density functional theory calculations. The chiral porphyrin-cages form complexes with achiral and chiral viologen-guests and upon binding one of the axial enantiomorphs of the guest is bound selectively, as is indicated by induced-electronic-dichroism-spectra in combination with calculations. This host-guest binding also leads to unusual enhanced vibrational circular dichroism, which is the result of a combination of phenomena, such as rigidification of the host and guest structures, charge transfer, and coupling of specific vibration modes of the host and guest. The results offer insights in how the porphyrin cage-compounds may be used to construct a future molecular Turing machine that can write chiral information onto polymer chains

Absolute configuration and host-guest binding of chiral porphyrin-cages by a combined chiroptical and theoretical approach

International audiencePorphyrin cage-compounds are used as biomimetic models and substrate-selective catalysts in supramolecular chemistry. In this work we present the resolution of planar-chiral porphyrin cages and the determination of their absolute configuration by vibrational circular dichroism in combination with density functional theory calculations. The chiral porphyrin-cages form complexes with achiral and chiral viologen-guests and upon binding one of the axial enantiomorphs of the guest is bound selectively, as is indicated by induced-electronic-dichroism-spectra in combination with calculations. This host-guest binding also leads to unusual enhanced vibrational circular dichroism, which is the result of a combination of phenomena, such as rigidification of the host and guest structures, charge transfer, and coupling of specific vibration modes of the host and guest. The results offer insights in how the porphyrin cage-compounds may be used to construct a future molecular Turing machine that can write chiral information onto polymer chains