Measuring vibrations on a biofidelic brain using ferroelectret nanogenerator.

Our knowledge of traumatic brain injury has been fast growing with the emergence of new markers pointing to various neurological changes that the brain undergoes during an impact or any other form of concussive event. In this work, we study the modality of deformations on a biofidelic brain system when subject to blunt impacts, highlighting the importance of the time-dependent behavior of the resulting waves propagating through the brain. This study is carried out using two different approaches involving optical (Particle Image Velocimetry) and mechanical (flexible sensors) in the biofidelic brain.

A dual light-driven palladium catalyst: Breaking the barriers in carbonylation reactions.

Transition metal-catalyzed coupling reactions have become one of the most important tools in modern synthesis. However, an inherent limitation to these reactions is the need to balance operations, because the factors that favor bond cleavage via oxidative addition ultimately inhibit bond formation via reductive elimination. Here, we describe an alternative strategy that exploits simple visible-light excitation of palladium to drive both oxidative addition and reductive elimination with low barriers.

A general approach to intermolecular carbonylation of arene C-H bonds to ketones through catalytic aroyl triflate formation.

The development of metal-catalysed methods to functionalize inert C-H bonds has become a dominant research theme in the past decade as an approach to efficient synthesis. However, the incorporation of carbon monoxide into such reactions to form valuable ketones has to date proved a challenge, despite its potential as a straightforward and green alternative to Friedel-Crafts reactions. Here we describe a new approach to palladium-catalysed C-H bond functionalization in which carbon monoxide is used to drive the generation of high-energy electrophiles.

Palladium-Catalyzed, Multicomponent Approach to β-Lactams via Aryl Halide Carbonylation.

A palladium-catalyzed multicomponent method for the synthesis of β-lactams from imines, aryl halides, and CO has been developed. This transformation proceeds via two tandem catalytic carbonylation reactions mediated by Pd(PBu) and provides a route to prepare these products from five separate reagents. A diverse range of polysubstituted β-lactams can be generated by systematic variation of the substrates.

Palladium Catalyzed, Multicomponent Synthesis of Fused-Ring Pyrroles from Aryl Iodides, Carbon Monoxide, and Alkyne-Tethered Imines.

A palladium-catalyzed multicomponent route to polycyclic pyrroles is described. Pd(PBu) was found to catalyze the coupling of (hetero)aryl iodides, two equivalents of carbon monoxide and alkyne-tethered imines into 1,3-dipoles (Münchnones), which undergo spontaneous, intramolecular 1,3-dipolar cycloaddition to form polycyclic pyrroles. The systematic variation of the alkyne, tethered-imine, or aryl iodide can allow the buildup of a range of pyrrole derivatives, where any of the substituents can be independently varied.

Computational Study of the Palladium-Catalyzed Carbonylative Synthesis of Aromatic Acid Chlorides: The Synergistic Effect of PtBu and CO on Reductive Elimination.

We describe herein computational studies on the unusual ability of Pd(PtBu ) to catalyze formation of highly reactive acid chlorides from aryl halides and carbon monoxide. These show a synergistic role of carbon monoxide in concert with the large cone angle PtBu that dramatically lowers the barrier to reductive elimination. The tertiary structure of the phosphine is found to be critical in allowing CO association and the generation of a high energy, four coordinate (CO)(PR )Pd(COAr)Cl intermediate.

From Aryl Iodides to 1,3-Dipoles: Design and Mechanism of a Palladium Catalyzed Multicomponent Synthesis of Pyrroles.

A palladium-catalyzed multicomponent synthetic route to polysubstituted pyrroles from aryl iodides, imines, carbon monoxide, and alkynes is described. To develop this reaction, a series of mechanistic studies on the [Pd(allyl)Cl]2/P(t)Bu3 catalyzed synthesis of imidazolinium carboxylates from aryl iodides, imines, and carbon monoxide were first performed, including model reactions for each individual step in the transformation. These show that this reaction proceeds in a concurrent tandem catalytic fashion, and involves the in situ formation of acid chlorides, N-acyl iminium salts, and ultimately 1,3-dipoles, i.