Upgrade of Biomass-Derived Levulinic Acid via Ru/C-Catalyzed Hydrogenation to γ‑Valerolactone in Aqueous−Organic−Ionic Liquids Multiphase Systems

A liquid triphase system made by an aqueous phase, an organic phase, and an ionic liquid was designed and applied to the catalytic hydrogenation/dehydration of biomass-derived levulinic acid to γ-valerolactone. This paper demonstrates that, by operating at 100−150 °C and 35 atm of H2, both in the presence of Ru/C or of a homogeneous Ru precursor, the use of the triphase system designed to match the investigated reaction allows the following: (1) to obtain up to quantitative conversions and 100% selectivity toward the desired product; (2) to recover the product by simple phase separation; and (3) to preserve the catalyst activity for in situ recycles without loss of metal. Globally the investigated reaction proves the concept that a cradle-to-grave approach to the design of a catalytic reaction system can improve the global sustainability of a chemical transformation by improving efficiency, product isolation, and catalyst recycle

Generation of luminescent defects in hBN by various irradiation methods

• Luminescent centres in hBN show good brightness and excellent quantum properties at room temperature, making them potential competitors with state-of-the-art quantum emitters.• The charged Boron vacancy (VB‾) is a luminescent centre featuring broad photoluminescence (PL) spectrum centered around 850 nm, along with magnetic properties with important applications in quantum sensing schemes.• In the present work, we use a Helium Ion Microscope (HIM) for irradiating hBN flakes to generate luminescent centres. We perform thorough PL characterization of these centres, showing that this technique can systematically produce high-quality luminescent emitters in hBN

Generation of luminescent defects in hBN by various irradiation methods

Hexagonal Boron Nitride (hBN) is a van der Waals (vdW) crystal with a very wide bandgap and often used as insulating layer for other vdW materials, like graphene. Luminescent centres in hBN have recently been gathering much attention because of their brightness and their excellent quantum properties at room temperature, which would make them competitive with state-of-the-art quantum emitters, like the NV center in diamond. Among the most studied luminescent centres in hBN, there is the charged Boron vacancy (V–B), which features a very broad photoluminescence (PL) spectrum centered around 850 nm, along with magnetic properties which have important applications in quantum sensing schemes. In the present work, we use a Helium Ion Microscope (HIM) for irradiating hBN flakes, either on bare Si/SiO2 substrate or stacked on thick Graphite flakes, to generate luminescent centres like the V–B. We perform in-depth PL characterization of these centres at different laser excitation wavelengths, power and polarization, and at cryogenic temperature, for different hBN thicknesses and for varying HIM irradiation fluences. Our results show that this technique can systematically produce high-quality luminescent emitters, in good agreement with literature, and allow us to have a good benchmark for further studies on V–B emitters in hBN

Towards a general ruthenium-catalyzed hydrogenation of secondary and tertiary amides to amines

A broad range of secondary and tertiary amides has been hydrogenated to the corresponding amines under mild conditions using an in situ catalyst generated by combining [Ru(acac)3], 1,1,1-tris(diphenylphosphinomethyl)ethane (Triphos) and Yb(OTf)3. The presence of the metal triflate allows to mitigate reaction conditions compared to previous reports thus improving yields and selectivities in the desired amines. The excellent isolated yields of two scale-up experiments corroborate the feasibility of the reaction protocol. Control experiments indicate that, after the initial reduction of the amide carbonyl group, the reaction proceeds through the reductive amination of the alcohol with the amine arising from collapse of the intermediate hemiaminal