Synthesis,Alkali Metal Picrate Extraction Properties,and X-Ray Crystal Structure of a Novel,Cage-Annulated Monoaza-18-Crown-6 Host

Compound 5, a cage-annulated monoaza-18-crown-6 macrocyclic polyether, has been synthesized, and its alkali metal picrate extraction capabilities have been assessed relative to those of the parent monoaza-18-crown-6 host system. It was observed that both 5 and monoaza-18-crown-6 are selective K⁺ picrate extractants; however, 5 appears generally to be a somewhat more efficient alkali metal picrate extractant than monoaza-18-crown-6. Interestingly, both the avidity and selectivity of 5 toward extraction of alkali metal picrates from aqueous solution into CHCl₃ appears to be pH dependent. In addition, the X-ray crystal structure of an unusual hydronium ion complex of 5 [i.e., 5(HCl)(H ₂ O)-(CHCl ₃ ) ₂] has been determined. The X-ray structure thus determined is compared with the corresponding structure of 5(HCl)(H ₂ O) that has been calculated via application of B3LYP Density Functional Theory.     

Triphenylsilanol–4,4′‐bipyridyl (4/1): the Z′ = 4 polymorph revisited

A fully ordered structure is reported for the polymorph of triphenylsilanol–4,4′‐bipyridyl (4/1), 4C₁₈H₁₆OSi·C₁₀H₈N₂, having Z′ = 4. The asymmetric unit contains four similar but distinct five‐molecule aggregates, in which the central bipyridyl unit is linked to two molecules of triphenylsilanol via O—H...N hydrogen bonds, with a further pair of triphenylsilanol molecules linked to the first pair via O—H...O hydrogen bonds. An extensive series of C—H...π(arene) hydrogen bonds links these aggregates into complex sheets. This structure is compared with a previously reported structure [Bowes, Ferguson, Lough & Glidewell (2003). Acta Cryst. B 59 , 277–286], which was based on an erroneous disordered structural model arising from a false direct‐methods solution with reference to a strong pseudo‐inversion centre.