the Ag'-Ag' distances are 493 and 490pm. Finally, the N-Ag' distances to the bipyridine N atoms are 244-251 pm. The coordination sphere around the central Ag' ion can be regarded as a distorted octahedron, that around each of the two other Ag' ions as a heavily distorted trigonal pyramid.A mononucleari' O1 and two dinucleari3"] Ag' complexes of related macrobicyclic ligands have been reported earlier. The cryptate 6 constitutes the first trinuclear Ag' complex. The three metal ions are arranged in a row, held at well-defined distances, and bound in two different environments, the central one being a tris-bipyridine Ag' site. Cryptand 3 offers the possibility of preparing homo-or heterometallic trinuclear metal cryptates that should display different binding, electrochemical, and photophysical properties for the terminal and the central metal ions, making available a range of novel features. For instance, a Cu'-Ag'-Cu' heterodinuclear complex has already been prepared. Further development of the present work will also include the encapsulation of organic substrates inside the cavities of macrobicycles 3 and 4 either as free bases or as protonated and alkylated derivatives. Experimental Procedures 3:To a stirred solution of Tren (1: 0.047 g, 0.32 mmol) in 5 mL of anhydrous acetonitrile was added dropwise at room temperature under argon a suspension of the dialdehyde 2 (colorless crystals, m.p. 228 "C; 0.1 g, 0.47 mmol) in acetonitrile ( 5 mL). The orange solid was filtered and recrystallized from methanol. Colorless crystals; m.p. 280°C (CH,OH); yield 78%; UV-VIS (CHCIJ CH,OH. 99:l): i .,,, [nm] ( E )

may be an indication that the "two-state model", on which the elucidation of the thermodynamic data is based, is most likely an oversimplification in this case. It seems reasonable that the reduction of the enthalpy term in the hybrid duplexes is due to a partly "incorrect" pairing geometry or to strain within the bicyclic strand. The reduction of the entropy term can be attributed to the reduced degree of rotational freedom in the sugar-phosphate backbone of the DNA analogues, although other contributions, especially from differences in duplex and single strand solvation, may also play an important role.

Maximal drei CuI‐Ionen und drei Catenanringe (schematische Darstellung rechts) enthalten die ersten Multiringcatenane, die nicht auf Makromonocyclen, sondern ‐bicyclen als Verknüpfungseinheit basieren. Die Synthese dieser supramolekularen Komplexe beruht auf dem dreidimensionalen Templateffekt der CuI‐Ionen.

Drei Stellen zum Andocken sorgen dafür, daß sich sechs Gäste im Hohlraum eines neuen Endorezeptors drängen. Über jeweils ein CuI‐Ion werden drei Phenanthrolinmoleküle in enge Nachbarschaft zueinander gebracht. Im FAB‐Massenspektrometer „fliegt”︁ der Wirt gemeinsam mit allen sechs Gästen als ein molekularer Überkomplex 1. Voluminösere Gastmoleküle werden nicht zu dritt eingelagert (R  CH3, p‐C6H4CH3; R′  H).

The macrobicyclic ligand 2 is synthesized in a one-step cyclization procedure. According to an X-ray structure analysis three dichloromethane guest molecules are included inside the cavity, whereas water and methanol are found outside the cavity. The rigid endo preorganization of the nitrogen donors allows the complexation of three 2,9-disubstituted 1,lO-phenanthrolines inside the cavity. Durch Ersatz der 2,2'-Bipyridin-durch 1,lO-Phenanthrolin-Briicken erhielten wir die molekularen Hohlraume 2 und 3, die aufgrund der zum Hohlraum-Innern gerichteten Orientierung der Donorzentren als Endorezept~rmolekiile[~~ bezeichnet werden konnen. Darstellung der Wirtverbindungen 2,9-Bis(4-methoxyphenyl)-l,lO-phenanthrolin