Nathan D. Shapiro

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This Communication demonstrates the generation of over 300 phase-separated systems-ranging from two to six phases-from mixtures of aqueous solutions of polymers and surfactants. These aqueous multiphase systems (MuPSs) form self-assembling, thermodynamically stable step-gradients in density using a common solvent, water. The steps in density between phases(More)
Experimental Details Materials: All reagents were purchased from Sigma-Aldrich and Alfa Aesar, and were used as supplied unless otherwise specified. All organic solvents were purchased from Sigma-Aldrich (dichloromethane, hexanes) or Fisher (200 proof ethanol) while water used in the synthesis was purified using a Millipore Q-POD water purification system.(More)
Recently, gold-carbenoid species have been proposed as inter-mediates in gold-catalyzed enyne rearrangements. 1 Additionally, the reaction of gold complexes with propargyl esters has been developed as an alternative approach to metal carbenoids capable of effecting olefin cyclopropanation; 2,3 however, to date, the reaction of electrophilic metals with(More)
The last decade has witnessed dramatic growth in the number of reactions catalyzed by electrophilic gold complexes. While proposed mechanisms often invoke the intermediacy of gold-stabilized cationic species, the nature of bonding in these intermediates remains unclear. Herein, we propose that the carbon-gold bond in these intermediates is comprised of(More)
Paramagnetic ionic liquids (PILs) provide new capabilities to measurements of density using magnetic levitation (MagLev). In a typical measurement, a diamagnetic object of unknown density is placed in a container containing a PIL. The container is placed between two magnets (typically NdFeB, oriented with like poles facing). The density of the diamagnetic(More)
Approaches to research in organic chemistry are as numerous as the reactions they describe. In this account, we describe our reactivity-based approach. Using our work in the area of gold catalysis as a background, we discuss how a focus on reaction mechanism and reactivity paradigms can lead to the rapid discovery of new synthetic tools. 1 Introduction 'Our(More)
Chiral Brønsted acids (proton donors) have been shown to facilitate a broad range of asymmetric chemical transformations under catalytic conditions without requiring additional toxic or expensive metals. Although the catalysts developed thus far are remarkably effective at activating polarized functional groups, it is not clear whether organic Brønsted(More)
The liquid-metal eutectic of gallium and indium (EGaIn) is a useful electrode for making soft electrical contacts to self-assembled monolayers (SAMs). This electrode has, however, one feature whose effect on charge transport has been incompletely understood: a thin (approximately 0.7 nm) film-consisting primarily of Ga(2)O(3)-that covers its surface when in(More)
The gold-catalyzed [3+3]-cycloaddition reaction of propargyl esters and azomethine imines has been developed. The reaction provides a rapid entry into a wide range of substituted tetrahydropyridazine derivatives from simple starting materials. A stepwise mechanism involving addition of the 1,3-dipole to a gold-carbenoid intermediate is proposed.