Cover Picture: Inclusion Behavior of β‐Cyclodextrin with Bipyridine Molecules: Factors Governing Host‐Guest Inclusion Geometries (Chem. Asian J. 3/2009)

A sytematic investigation of the molecular inclusion behavior by β‐cyclodextrin (gold) towards constitutionally different yet structurally similar bipyridine guests, demonstrates that differences of the nitrogen atom positions and the bridge bond linking the two pyridine rings of the bipyridine guests can significantly affect the binding abilities, inclusion geometries, and self‐assembly behavior of β‐cyclodextrin in both the solution and solid states. J. F. Stoddart and co‐workers suggest that these new superstructural and quantitative observations, with judicious constitutional design, allow highly ordered supramolecular arrays to be achieved conveniently in a controllable way. For more information, see their Full Paper on page 446 ff.

     

A Cobalt Metallacrown Anion Host with Guest‐Dependent Redox Activity

Two bowl‐shaped cavities , each having three OH^? hydrogen‐bond donors at its base, are present in double‐cone‐shaped metallacrown anion host [Co₆(μ‐OH)₆(μ‐L)₆]^m+ ( 1 ^{m +} ; HL=3{5}‐(pyrid‐2‐yl)‐5{3}‐(tert‐butyl)pyrazole). Depending on its affinity for the anions present, it can be isolated in its Co^III₃Co^II₃ (m=3; e.g., 1 (ClO₄)₃) and Co^III₂Co^II₄ (m=2; e.g., 1 (BF₄)₂ ? n H₂O) oxidation states. See picture for photographs of isolated salts.