No abstract

An integrated study of the organic–inorganic framework material zinc cyclohexane trans‐1,2‐dicarboxylate involving synthesis, structure elucidation, computer simulation, and calorimetry shows that the chiral R,R form (right in picture) is less stable than its racemic R,R/S,S analogue (left) and adopts a layered structure with a fundamentally different topology. The results point to the possibility that the structural diversity of racemic frameworks and their homochiral analogues may be much greater than has hitherto been suspected.

Stimulation of insulin secretion by 5-methylcoumarins and its sulfur analogues isolated from Clutia lanceolata Forssk.

The new symmetric acyclic N,N’-bis(1-pyrenyl) squaramide (H2L) functionalized with the pyrene moiety as a fluorogenic fragment has been designed and its ability to selectively detect specific anions and metals investigated. H2L selectively binds Cl− both in solution (DMSO 0.5% H2O and MeCN) and in the solid state, and allows to selectively detect Cu2+ in MeCN with the formation of a 2:1 metal-receptor complex, with a green intense emission appreciable by naked eye under the UV lamp. The H2L copper complex preserves its emission properties in the presence of Cl−. The addition of basic anions (OH−, CN−, and F−) up to 10 equivalents caused the deprotonation of the squaramide NHs and a dramatic change of the emission properties of the H2L copper complex.

A new polymorph of anhydrous pyridine-2,6-dicarboxylic (dipicolinic) acid in which salt formation is favoured over carboxylic acid dimerisation is reported, together with the solidstate architectures of a novel dipicolinic acid dihydrate and a monohydrate structure of the 4-chloro analogue.