Induction of chiral porous solids containing only achiral building blocks

In many areas of chemistry the synthesis of chiral compounds is a target of increasing importance. They play a vital role in biological function and in many areas of society and science, including biology, medicine, biotechnology, chemistry and agriculture. Many pharmaceutical molecules, like their biological targets, are chiral and it is therefore easy to understand the growing demand for efficient methods of producing enantiomerically pure compounds. This is equally true for the preparation of chiral solids, which have potential applications in asymmetric catalysis, chiral separations and the like. In this Review we will consider recent progress and future potential in the development of methods for the preparation of chirally pure solids, in particular where the building blocks of the structure are achiral themselves. We will discuss strategies for the synthesis of both inorganic (for example, zeolites) and inorganic-organic hybrid (for example, metal organic framework) chiral porous solids.</p

‘Superior to Disney’: colour animation at Lenfilm, 1936-41

This article examines the phenomenon of colour-film animation at Lenfilm during the period 1936–1941. It discusses the development of colour technologies at the studio during the 1930s and the ways in which its artists responded to the aesthetic challenge of colour. Three of the seven short films produced during this period have been selected as case studies; they are examined here in the context of filmed animations in the Soviet Union during the 1930s, in particular the debates prompted by the screening of three Disney animations in Technicolor at the Moscow International Film Festival in 1935. The formal analysis of the case studies is based on the digital restorations in recent years at the Russian State Film Archive (Gosfilmfond), but also the inspection of one nitrate-positive of Mstislav Pashchenko’s Dzhiabzha (1939), which has survived intact at the archive. The technical difficulties posed by the hydrotype process developed at Lenfilm, as well as the challenge of producing sufficient prints for mass distribution, also form part of the discussion

Inorganic Niobium and Tantalum Octahedral Cluster Halide Compounds with Three-dimensional Frameworks: A Review on their Crystallographic and Electronic Structures

International audienceThis review summarizes the development of the rich crystal and bonding chemistry of face-capped and edge-bridged inorganic niobium and tantalum octahedral cluster halide compounds, with a particular emphasis on those showing three-dimensional cluster frameworks. Discussion is made on varied structures and bonding which are intimately linked to the valence electron concentration, i.e., the number of electrons that held the octahedral metal cluster architecture. Exploration of the literature indicates that apart from Nb6I11 and derivatives, which show electron-deficient face-capped M6Xi8Xa6 units, compounds containing edge-bridged M6Xi12Xa6 motifs are the most largely encountered. Closed-shell compounds with a valence electron concentration of 16 are predominant, although a few 15-electron open-shell magnetic compounds or even 14-electron closed-shell species have also been reported. Particularly interesting from a structural point of view is the fashion in which these face-capped and edge-bridged clusters “pack” in crystals. The astonishing diversity of structural types, which are observed, is mainly due to the flexibility of the halogen ligands to coordinate in various manners to metal atoms. However, a rigorous structural analysis of these compounds reveals no close relationship between the valence electron concentration and the variability of the intercluster connections and/or the nature of the counterions. Indeed, the main bonding features of these compounds can be understood from the delocalized bonding picture of isolated “molecular-like” M6Xi8Xa6 or M6Xi12Xa6 clusters