This Review deals with the evolving field of polyhalogen chemistry, specifically polyhalogen anions (polyhalides). In addition to a historical outline, current progress in synthetic approaches towards the formation of polyfluorides, polychlorides, polybromides, and polyinterhalides is also illustrated. The structural diversity of polyhalides has substantially increased in the past decade, especially for polychlorides and polybromides, which are commonly characterized by single‐crystal X‐ray diffraction, Raman spectroscopy, and quantum‐chemical calculations. Polyfluorides have been examined by sophisticated state‐of‐the‐art quantum‐chemical calculations and investigated spectroscopically in noble gas matrix‐isolation experiments under cryogenic conditions at 4 K. The bonding in such polyhalide systems is also discussed. The last Section deals with applications of polyhalides in halogenation reactions and electrochemistry as well as their use as reactive ionic liquids, emphasizing the promising future of polyhalogen chemistry.

Two-dimensional (2D) materials offer numerous advantages for electrochemical energy storage and conversion due to fast charge transfer kinetics, highly accessible surface area, and tunable electronic and optical properties. Stacking of 2D materials generates heterogeneous interfaces that can modify native chemical and physical material properties. Here, we demonstrate that local strain at a carbon-MoS2 interface in a vertically stacked 2D material directs the pathway for chemical storage in MoS2 on lithium metal insertion. With average measured MoS2 strain of ∼0.1% due to lattice mismatch between the carbon and MoS2 layers, lithium insertion is facilitated by an energy-efficient cation-exchange transformation. This is compared with low-voltage lithium intercalation for unstrained MoS2. This observation implies that mechanical properties of interfaces in heterogeneous 2D materials can be leveraged to direct energetics of chemical processes relevant to a wide range of applications such as electrochemical energy storage and conversion, catalysis and sensing.

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Abstract. We prove a generalized Bogomolov-Gieseker inequality as conjectured by Bayer, Macrì and Toda for the smooth quadric threefold. This implies the existence of a family of Bridgeland stability conditions.

We show the existence of Bridgeland stability conditions on all Fano threefolds, by proving a modified version of a conjecture by Bayer, Toda, and the second author. The key technical ingredient is a strong Bogomolov inequality, proved recently by Chunyi Li. Additionally, we prove the original conjecture for some toric threefolds by using the toric Frobenius morphism. Comment: 24 pages, 1 figure. Fifth version: Official version of the journal

Abstract. In these lecture notes we give an introduction to Bridgeland stability conditions on smooth complex projective varieties with a particular focus on the case of surfaces. This includes basic definitions of stability conditions on derived categories, basics on moduli spaces of stable objects and variation of stability. These notes originated from lecture series by the first author at the summer school Recent advances in algebraic and arithmetic geometry, Siena, Italy, August 24-28, 2015 and at the school Moduli of Curves, CIMAT, Guanajuato, Mexico, February 22 -March 4, 2016.

A reference electrode is an essential component of all three-electrode electrochemical measurements. Common commercial reference electrodes, including the saturated calomel electrode and Ag/AgCl reference electrode, are expensive with the former containing toxic mercury. Cheaper alternatives have been proposed including Ag/AgCl references made from pipets and test tubes. However, electrodes prepared in this way are difficult to work with and are limited by the size and shape of glass casings that are available. This paper proposes an in-house manufactured Ag/AgCl reference electrode that uses some 3D-printed components in the fabrication process. This electrode is cheap to manufacture ($5 vs $60–100 CAD for the commercial reference electrode), and the design can be quickly altered due to the 3D printer’s capabilities in rapidly printing new electrode shapes to suit different analysts’ needs. The lab-made reference electrodes demonstrated stability and consistency in peak potential measurements in the cyclic voltammetry (CV) experiments. In ferricyanide CV tests, the recorded differences in anodic and cathodic peak potential (ΔE p) values for the commercial reference electrode and both lab-made electrodes were 68 ± 9%, 70 ± 12%, and 69 ± 13%, respectively. For all tests, the results were statistically comparable with those of the commercial Ag/AgCl reference electrode.

Abstract. We give a counterexample to the generalized Bogomolov-Gieseker inequality for threefolds conjectured by Bayer, Macrì and Toda using the blow up of a point over three dimensional projective space.