Manganese(I)-Catalyzed H-P Bond Activation via Metal-Ligand Cooperation

Here we report that chiral Mn(I) complexes are capable of H-P bond activation. This activation mode enables a general method for the hydrophosphination of internal and terminal α,β-unsaturated nitriles. Metal-ligand cooperation, a strategy previously not considered for catalytic H-P bond activation, is at the base of the mechanistic action of the Mn(I)-based catalyst. Our computational studies support a stepwise mechanism for the hydrophosphination and provide insight into the origin of the enantioselectivity

Controlling the Assembly of Cellulose-Based Oligosaccharides through Sequence Modifications

Peptides and nucleic acids with programmable sequences are widely explored for the production of tunable, self-assembling functional materials. Herein we demonstrate that the primary sequence of oligosaccharides can be designed to access materials with tunable shapes and properties. Synthetic cellulose-based oligomers were assembled into 2D or 3D rod-like crystallites. Sequence modifications within the oligosaccharide core influenced the molecular packing and led to the formation of square-like assemblies based on the rare cellulose IVII allomorph. In contrast, modifications at the termini generated elongated aggregates with tunable surfaces, resulting in self-healing supramolecular hydrogels

Investigations towards the stereoselective organocatalyzed Michael addition of dimethyl malonate to a racemic nitroalkene: possible route to the 4-methylpregabalin core structure

Chiral derivatives of γ-aminobutyric acid are widely used as medicines and can be obtained by organocatalytic Michael additions. We show here the stereoselective synthesis of 4-methylpregabalin stereoisomers using a Michael addition of dimethyl malonate to a racemic nitroalkene. The key step of the synthesis operates as a kinetic resolution with a chiral squaramide catalyst. Furthermore, specific organocatalysts can provide respective stereoisomers of the key Michael adduct in up to 99:1 er

Bottom-Up Approach to Understand Chirality Transfer across Scales in Cellulose Assemblies

International audienceCellulose is a polysaccharide that displays chirality across different scales, from the molecular to the supramolecular level. This feature has been exploited to generate chiral materials. To date, the mechanism of chirality transfer from the molecular level to higher-order assemblies has remained elusive, partially due to the heterogeneity of cellulose samples obtained via top-down approaches. Here, we present a bottom-up approach that uses well-defined cellulose oligomers as tools to understand the transfer of chirality from the single oligomer to supramolecular assemblies beyond the single cellulose crystal. Synthetic cellulose oligomers with defined sequences self-assembled into thin micrometer-sized platelets with controllable thicknesses. These platelets further assembled into bundles displaying intrinsic chiral features, directly correlated to the monosaccharide chirality. Altering the stereochemistry of the oligomer termini impacted the chirality of the self-assembled bundles and thus allowed for the manipulation of the cellulose assemblies at the molecular level. The molecular description of cellulose assemblies and their chirality will improve our ability to control and tune cellulose materials. The bottom-up approach could be expanded to other polysaccharides whose supramolecular chirality is less understood

CCDC 1937210: Experimental Crystal Structure Determination

Related Article: Denisa Vargová, Juana M. Pérez, Syuzanna R. Harutyunyan, Radovan Šebesta|2019|Chem.Commun.|55|11766|doi:10.1039/C9CC05041

Parents’ intention to vaccinate their children against COVID-19

Usually, parents and caregivers are the ones responsible for children's vaccination, their intention to vaccinate children depending on many factors. In a society where almost half of adults have refused to take a jab against COVID-19, it is important to know which factors increase or decrease the odds of a child getting vaccinated. In the present study, we examined parents’ reasons for/against children vaccination and predictors of this intention. We found that about 30% of parents intended to have their children vaccinated to protect the health of children and their close ones. On the other hand, parents who did not intend to have their children vaccinated were typically afraid of long-term consequences of vaccination and its side effects, with less than one fifth of them being skeptical about vaccination per se. Using logistic regression analyses, we found that a higher willingness to vaccinate was in male, older parents, and those with higher (socio)economic status. Parents with a higher adherence to restrictions, and higher trust in government and authorities were more likely to vaccinate their children. Moreover, parents who had themselves been vaccinated or were more positive towards vaccination in general were much more willing to vaccinate their children. On the contrary, belief in conspiracy theories decreased this intention 10-times. No other variables (e.g., demographic characteristics, mental health indicators, or direct experience with COVID-19) significantly predicted parents’ intention to vaccinate their children. The study offers several implications related to the complexity of factors which determine hesitant parents’ intention to vaccinate their children. We aimed to answer questions on how, when, and by whom parents should be approached to improve their awareness on vaccination decisions