Carlos Pacheco

We report the use of an online electrochemistry/mass spectrometry platform to develop a redox neutral electrosynthesis of 5-membered rings via [3 + 2] annulation of N -cyclopropylanilines and alkenes, without additional oxidant, reductant or catalyst.

The synthesis of 2-dimensional (2D) zeolites has garnered attention owing to their superior properties for applications that span catalysis to selective separations. Prior studies of 2D zeolite catalysts demonstrated enhanced mass transport for improved catalyst lifetime and selectivity. Moreover, the significantly higher external surface area of 2D materials allows for reactions of bulky molecules too large to access interior pores. There are relatively few protocols for preparing 2D materials owing to the difficultly of capping growth in one direction to only a few unit cells. To accomplish this, it is often necessary to employ complex, commercially-unavailable organic structure-directing agents (OSDAs) prepared via multistep synthesis. However, a small subset of zeolite structures exist as naturally layered materials where post-synthesis steps can be used to exfoliate samples and produce ultrathin 2D nanosheets. In this study, we selected a common layered zeolite, the MWW framework, to explore methods of preparing 2D nanosheets via a one-pot synthesis in the absence of complex organic templates. Using a combination of high-resolution microscopy and spectroscopy, we show 2D MMW-type layers with an average thickness of 3.5 nm (ca. 1.5 unit cells) can be generated using the surfactant cetyltrimethylammonium (CTA), which operates as a dual OSDA and exfoliating agent to affect Al siting and eliminates the need for post-synthesis exfoliation, respectively. We tested these 2D catalysts using a model reaction that assesses external (surface) Brønsted acid sites and ob-served a marked increase in the conversion relative to 3-dimensional MWW (MCM-22) and 2D layers prepared from post-synthesis exfoliation (ITQ-2). Collectively, our findings identify a facile and effective route to directly synthesize 2D MWW-type materials, which may prove to be more broadly applicable to other layered zeolites.

The reaction of molybdenum(II) and chromium(II) acetates with squaric acid in degassed and deionized water under hydrothermal conditions at 150 °C is described. The products have been formulated as M₂(μ-OH)₂(μ-C₄O₄)₂(H₂O)₄·2H₂O, where M = Cr (1) and Mo (2), based on combustion elemental analysis, infrared spectroscopy, magic angle spinning (MAS) solid-state carbon-13 nuclear magnetic resonance (NMR), and single-crystal X-ray diffraction. The edge-shared bioctahedral structures involve doubly bridging hydroxide ligands and μ-squarate ligands. The chromium compound lacks a direct metal–metal-bonding interaction, while in contrast the molybdenum compound contains a Mo–Mo bond [2.491(2) Å]. The nature of the Mo–Mo-bonding interaction is compared with that of other similar d³–d³ dimers.

EGCG forms protein-polyphenol complexes with α₂-gliadin (57–89) in a multi-phase reaction.