New indole trimers as precursors for molecular electronic materials

We have prepared two new C₃-symmetric, substituted-triazatruxene molecules using a facile one-pot trimerisation of 5-carboxyindole and 6-bromoindole in acetic acid using Br₂, giving 2a and 3a, respectively. These were subsequently modified by the addition of six alkyl chains to the N- and carboxyl-positions of 2a giving 2b and three alkyl chains to the N-positions of 3a giving 3b. The new molecules were characterised using cyclic voltammetry, UV/vis and emission spectroscopy, DFT calculations and in the case of 3b, field-effect transistor measurements showing gate-modulated source-drain current. These represent a straightforward route to large polyaromatic molecules with easily-modified side groups and are suitable as building blocks for synthesis of functional molecules for materials.     

Regioselective Arylation and Alkynylation of 2,3‐Dibromo‐1H‐inden‐1‐one by Suzuki?Miyaura and Sonogashira Cross‐Coupling Reactions

Suzuki? Miyaura reactions of 2,3‐dibromo‐1H‐inden‐1‐one afforded a wide range of arylated 1H‐inden‐1‐ones. Sonogashira cross‐coupling reactions gave alkynylated indenones. The reactions proceeded with very good regioselectivity in the less sterically hindered and more electron‐deficient position 3.     

A critical review-promises and barriers of conversion electrodes for Li-ion batteries

Conversion-type electrode materials are discussed in this critical review. Most of the conversion materials are significantly less expensive than modern intercalation-type materials, and the materials involved are appreciably abundant in the nature. However, up to now, no practically viable battery with conversion material-based electrodes was reported, as there are several major barriers to a practical employment of these materials. First, material utilization and cell energy performance are seriously compromised by a low conductivity of the most conversion materials and by a substantial electrolyte involvement in the electrochemical process. Second, the conversion reactions usually demonstrate a severe volume effect, and also conversion electrodes interact with electrolyte developing thick and resistant solid electrolyte interphase films; both of these features result in impractically low electrode cyclability. Third, a large lithiation/de-lithiation voltage hysteresis results in impractically low charge/discharge energy efficiency and suggests a severe battery heating in the course of the battery operation. All these problems present serious challenges for the researchers in the field; the approaches for handling these issues are discussed in the review. For the foreseeable future, there are grounds to expect progress in tackling some of these issues. The issue of high voltage hysteresis is a bottleneck, though, and it actually precludes conversion materials from any practical application.