Modulated proton transport plays significant roles in biological processes such as ATP synthesis as well as in technologically important applications including, for example, hydrogen fuel cells. The state-of-the-art proton-exchange membrane is the sulphonated tetrafluoroethylene copolymer Nafion developed by DuPont in the late 1960s, with a high proton conductivity. However, actively switchable proton conduction, a functional mimic of the ion transport within a cell membrane, has yet to be realized. Herein, we report the electrostatic gating of proton transport within aligned mesoporous silica thin film. It is observed that surface-charge-mediated transport is dominant at low proton concentrations. We have further demonstrated that the proton conduction can be actively modulated by two-fourfold with a gate voltage as low as 1 V. Such artificial gatable ion transport media could have potential applications in nanofluidic chemical processors, biomolecular separation and electrochemical energy conversion.

Getting to the bottom of groundwater: The development of a reliable, portable, and simple‐to‐use device for detecting arsenic in groundwater is urgently needed in developing nations such as Bangladesh, where contaminated groundwater is at the root of a public health crisis. Toward this end, a highly sensitive platform utilizing surface‐enhanced Raman spectroscopy (SERS, see picture) is used to quantitatively detect arsenate in water down to 1 ppb.

A number of modifications to a previously published distillation-free solvent purification system are suggested. The recommended changes result in a substantial savings of cost, space, and time. Several problems encountered in the purification of ethereal solvents are discussed.

We report an improved synthesis of 1,1′-diaminoferrocene, employing the reduction of 1,1′diazidoferrocene with H 2 -Pd/C, along with extensive characterization data for both compounds. Diaminoferrocene undergoes a reversible 1eoxidation in CH 3 CN at a potential of -602 mV vs Fc 0/+ , one of the most negative redox potentials for a ferrocene derivative. The chemical reversibility of this process was confirmed by isolation of the stable, 17-electron [Fc(NH 2 ) 2 ] + cation as PF 6 -, OTf -, and TCNEsalts. In the solid state, diaminoferrocene exists in two conformations: one with the NH 2 groups eclipsed, and the other with the NH 2 groups offset by one-fifth turn around the Cp-Fe-Cp axis. Diazidoferrocene, on the other hand, exhibits only the fully eclipsed conformation in the solid state. The Fe-Cp(centroid) vectors in the diazidoferrocene molecules are roughly aligned with the crystallographic c-axis, and the molecules form layers perpendicular to this axis. The compound is thermally unstable at elevated temperatures, and rapid heating above its melting point results in explosion.

While β-diketiminate (BDI or 'nacnac') ligands have been widely adopted to stabilize a wide range of metal ions in multiple oxidation states and coordination numbers, in several occurrences these ligands do not behave as spectators and participate in reactivity. Besides unwanted decomposition processes, BDI redox non-innnocence and unusual metal-ligand cooperative activation of substrates yielding attractive reactivity have been reported. This feature article will provide a comprehensive analysis of the various transformations involving BDI ligand platforms in coordination compounds across the periodic table.

New tris-amidinate actinide (Th, U) complexes containing a rare O-bound terminal phosphaethynolate (OCP–) ligand were synthesized and fully characterized.

Reaction of (CpSiMe(3))(3)U or (CpSiMe(3))(3)Nd with (Cp*Al)(4) or Cp*Ga (Cp* = C(5)Me(5)) afforded the isostructural complexes (CpSiMe(3))(3)M-ECp* (M = U, E = Al (1); M = U, E = Ga (2); M = Nd, E = Al (3); M = Nd, E = Ga (4)). In the case of 1 and 2 the complexes were isolated in 39 and 90% yields, respectively, as crystalline solids and were characterized by single-crystal X-ray diffraction, variable-temperature (1)H NMR spectroscopy, elemental analysis, variable-temperature magnetic susceptibility, and UV-visible-NIR spectroscopy. In the case of 3 and 4, the complexes were observed by variable-temperature (1)H NMR spectroscopy but were not isolated as pure materials. Comparison of the equilibrium constants and thermodynamic parameters DeltaH and DeltaS obtained by (1)H NMR titration methods revealed a much stronger U-Ga interaction in 2 than the Nd-Ga interaction in 4. Competition reactions between (CpSiMe(3))(3)U and (CpSiMe(3))(3)Nd indicate that Cp*Ga selectively binds U over Nd in a 93:7 ratio at 19 degrees C and 96:4 at -33 degrees C. For 1 and 3, comparison of (1)H NMR peak intensities suggests that Cp*Al also achieves excellent U(III)/Nd(III) selectivity at 21 degrees C. The solution electronic spectra and solid-state temperature-dependent magnetic susceptibilities of 1 and 2, in addition to X-ray absorption near-edge structure (XANES) measurements from scanning transmission X-ray microscopy (STXM) of 1, are consistent with those observed for other U(III) coordination complexes. DFT calculations using five different functionals were performed on the model complexes Cp(3)M-ECp (M = Nd, U; E = Al, Ga), and empirical fitting of the values for Cp(3)M-ECp allowed the prediction of binding energy estimates for Cp*Al compounds 1 and 3. NBO/NLMO bonding analyses on Cp(3)U-ECp indicate that the bonding consists predominantly of a E-->U sigma-interaction arising from favorable overlap between the diffuse ligand lone pair and the primarily 7s/6d acceptor orbitals on U(III), with negligible U-->E pi-donation. The overall experimental and computational bonding analysis suggests that Cp*Al and Cp*Ga behave as good sigma-donors in these systems.

Acid-catalyzed additions of amines to alkenes are generally unsuccessful due to the buffering effect of the amine substrate. 1 Friedel-Crafts alkylations of arylamines are hindered by coordination of the amine to the Lewis acid catalyst. 2 A recent communication by Hartwig et al. reports that several common Brønsted acids catalyze the intramolecular hydroamination of tosyl-protected amino olefins. 3 Beller and co-workers have reported that alkylations of electron-rich anilines with styrene are promoted with HBF 4 ·Et 2 O. 2b,4 Herein we report the first homogeneous 5 acid catalyst that promotes both hydroamination and hydroarylation reactions of anilines and alkenes, including simple cyclic alkenes and dienes. These transformations are air-and moisture-tolerant and can be controlled to favor either N-H or Ar-H addition products based on reaction conditions and aniline substitution pattern. The key to the activity of this system is that the acid counteranion has a dramatic effect on reaction efficiency.In the course of our studies on metal-catalyzed hydroamination reactions, 6 we found that Ph 3 CB(C 6 F 5 ) 4 (1) catalyzes the reaction of norbornene with aniline. Both hydroamination (2) and ortho-hydroarylation (3) products are formed using 5 mol % of 1 (eq 1). 7(1)