Following on their seminal theoretical work on the pleated β-sheet published by Pauling and Corey in 1951, the rippled β-sheet was hypothesized by the same authors in 1953. In the...

We report the first example of linker modification for an N-donor Ag-based cationic material while maintaining and in some cases increasing the anion exchange capacity. Cationic silver­(I) pyrazine nitrate selectively traps harmful oxo-anions from water such as permanganate, perrhenate and a variety of α,ω-alkanedicarboxylates. We chose these anions as initial examples of exchange for potential water purification. The host–guest interaction between the cationic layers of π-stacked silver pyrazine polymers and the incoming/outgoing interlamellar anions allows for the exchange. The exchange capacity over 24 h reached 435 and 818 mg/g for permanganate and perrhenate, respectively, a record for a crystalline metal–organic material and over five times the exchange capacity compared to commercial resin. The material also undergoes organic exchange as an analog for pharmaceutical waste, some of which have a carboxylate functionality at the neutral pH range typical of natural water sources. Both the as-synthesized and exchanged materials are characterized by a variety of analytical techniques.

We report the use of a gallium (Ga)-rich aluminum (Al) composite to enhance the formation of Al nanoparticles and to facilitate its ability to split water to generate hydrogen at ambient conditions. The synthesis of this Ga−Al composite occurs without the need of an inert atmosphere or mechanical aid. Commercial Al can be used, including postconsumer aluminum foil that is usually discarded. Characterization of the Ga−Al composite with scanning electron microscopy, energy-dispersive X-ray spectroscopy, and powder X-ray diffraction illustrates that the Ga acts to dissolve the aluminum oxide coating of the Al nanoparticles. The pristine nanoparticles are then available for continuous water splitting and on-demand hydrogen generation through the Grotthuss mechanism. The water-splitting reaction does not require an applied potential and functions at ambient conditions and neutral pH to rapidly generate 130 mL (5.4 mmol) of hydrogen per gram of alloy. Any available source of water can be used including wastewater, commercial beverages, or even ocean water, with no generation of chlorine gas, as confirmed by gas chromatography−mass spectrometry. In addition, Ga remains intact, allowing it to be collected and reused indefinitely. The Ga−Al alloy is stable under cyclohexane for at least 3 months so it can be preprepared for a later use. As an initial example of the application of evolved hydrogen, we show a hydrogenation reaction.

We report four lanthanide metal–organic frameworks based on 2,6-naphthalenedicarboxylate which displays multiple bonding modes, implying more structures await discovery.

We report the high-capacity and selective uptake of Cr(VI) from water using the coordination polymer silver bipyridine acetate (SBA, [Ag(4,4′-bipy)][CH 3 CO 2 ]•3H 2 O). Cr capture involves the release of acetate, and we have structurally characterized two of the product phases that form: silver bipyridine chromate (SBC, [Ag(4,. SBA maintains a high Cr uptake capacity over a wide range of pH values (2−10), reaching a maximum of 143 mg Cr/g at pH 4. This Cr uptake capacity is one of the highest among coordination polymers. SBA offers the additional benefits of a onestep, room temperature, aqueous synthesis and its release of a nontoxic anion following Cr(VI) capture, acetate. Furthermore, SBA capture of Cr(VI) remains >97% in the presence of a 50-fold molar excess of sulfate, nitrate, or carbonate. We also investigated the Cr(VI) sequestration abilities of silver 1,2-bis(4-pyridyl)ethane nitrate (SEN, [Ag(4,][NO 3 ]) and structurally characterized the silver 1,2-bis(4-pyridyl)ethane chromate (SEC, SLUG-58, [Ag(4,4′-bpe)][CrO 4 ] 0.5 ) product. SEN was, however, a less effective Cr(VI) sequestering material than SBA.