CO hydrogenation is attracting increasing attention as a sustainable route to produce formic acid, a commodity and potential energy vector. Here, bifunctional catalysts comprising metal nanoparticles deposited on bulk graphitic carbon nitride were assessed under base-free conditions, identifying supported Pd as the best performer. The catalyst productivity was enhanced by maximizing the edge-defects of the g-C N carrier, amino groups able to activate CO , and by generating welldispersed 5 nm Pd particles, required to split H . Bottom-up synthesis methods, that is, hard-templating and carbon enrichment upon polymerization, and top-down strategies, that is, thermal exfoliation of the as-prepared solid, were explored to boost the defects, the nature and density of which were evaluated by thermal and (in situ) spectroscopic techniques. After optimization of temperature, pressure, and reaction time, a 20 times higher turnover frequency compared with the best Pd/g-C N catalyst reported producing formic acid from CO without base was attained. This activity level was retained upon recycling with intermediate catalyst regeneration at mild temperature.
A simple regiospecific route to otherwise problematic substituted tetracenes is described. The diverse cores (E)-1,2-Ar CH (HOCH )C=C(CH OH)I (Ar =Ph, 4-MePh, 4-MeOPh, 4-FPh) and (E)-1,2-I(HOCH )C=C(CH OH)I, accessed from ultra-low cost HOCH C≡CCH OH at multi-gram scales, allow the synthesis of diol libraries (E)-1,2-Ar CH (HOCH )C=C(CH OH)CH Ar (Ar =Ph, 4-MePh, 4-iPrPh, 4-MeOPh, 4-FPh, 4-BrPh, 4-biphenyl, 4-styryl; 14 examples) by efficient Negishi coupling. Copper-catalysed aerobic oxidation cleanly provides dialdehydes (E)-1,2-Ar CH (CHO)C=C(CHO)CH Ar , which in many cases undergo titanium(IV) chloride-induced double Bradsher closure, providing a convenient method for the synthesis of regiochemically and analytically pure tetracenes (12 examples). The sequence is typically chromatography-free, scalable, efficient and technically simple to carry out.
Cellular delivery of DNA vectors
for the expression of therapeutic
proteins is a promising approach to treat monogenic disorders or cancer.
Significant efforts in a preclinical and clinical setting have been
made to develop potent nonviral gene delivery systems based on lipoplexes
composed of permanently cationic lipids. However, transfection efficiency
and tolerability of such systems are in most cases not satisfactory.
Here, we present a one-pot combinatorial method based on double-reductive
amination for the synthesis of short-chain aminolipids. These lipids
can be used to maximize the DNA vector delivery when combined with
the cationic lipid 1,2-dioleoyl-3-trimethylammonium propane (DOTAP).
We incorporated various aminolipids into such lipoplexes to complex
minicircle DNA and screened these systems in a human liver-derived
cell line (HuH7) for gene expression and cytotoxicity. The lead aminolipid
AL-A12 showed twofold enhanced gene delivery and reduced toxicity
compared to the native DOTAP:cholesterol lipoplexes. Moreover, AL-A12-containing
lipoplexes enabled enhanced transgene expression
in vivo
in the zebrafish embryo model.
Invited for this month′s cover is the group of Javier Pérez‐Ramírez at ETH Zurich. The image shows the Pisa tower supported by an ant standing on carbon nitride and a palladium nanoparticle, which symbolizes the CO2‐based production of formic acid through bifunctional catalysis. The Full Paper itself is available at https://doi.org/10.1002/cssc.201801920.
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