Neue extrem deformierte (Biphenylen‐)Kohlenwasserstoff‐Gerüste

New Extremely Deformed (Biphenylene)Hydrocarbon Skeletons The tetracyclic carbon skeleton 2-oxo[3](1,8)biphenylenophane (4) was synthesized by cyclization of a mixture of the bis(bromomethyl) compounds 7a, b with p-tolylsulfonylmethyl isocyanide. 2-Hydroxy[3](1,8)biphenylenophane (5) and the [3](1,8)biphenylenophane hydrocarbon 6 were obtained by reduction of 4 with LiAlH4 and NaBH4, respectively. X-ray analyses of 4 and 6 illustrate the dramatic deformation of bond lengths and angles in these molecules.

A New Macrobicyclic Tris-bipyridine Ligand and Its Cu2I and Ag3I Complexes

Self-assembly by co-ordination and strong hydrogen bonding. X-ray crystal structures of a dimeric trisodium complex of a new acidic complexing ligand and its dihydrate

Abstract The new acidic complexing ligand triethanolamine-O,O,O-triacetic acid, 3, is synthesized by reaction of triethanolamine with chloroacetic acid in the presence of sodium tert-butoxide. The resulting Na complex, 4, and its dihydrate, 5, contain two ligand molecules, both with one Na+ ion interaction and both co-ordinated to a third, central, Na+ ion. In addition the acidic ligands are hydrogen bonded to each other, like carboxylic acids, and in 4, by three crystallographically symmetric hydrogen bonds, while in 5, due to the breakdown of symmetry, two normal and one crystallographically symmetrical hydrogen bond. Inside this extraordinary dimeric assembly (a pseudo-cryptate) are the …

Mit Donorzentren versehener korbförmiger Molekülhohlraum — Darstellung, Struktur, Eigenschaften

Basket-shaped Molecular Cavity-Containing Donor Centres — Synthesis, Structure, Properties The macrocyclic basket-shaped molecule 2, composed of three 4-donor-substituted pyridine units, is synthesized by cyclisation of the chloromethyl compound 7 with sulfonamide 8. The X-ray structure analysis of 2 gives an impression of the shape of the molecular basket. Furthermore it demonstrates that the toluenesulfonamide residues interlink, creating dimeric units of 2 in the crystal.

Molecular Ribbons Containing Pyridine Rings

The first synthesis of the ribbon-like compounds 6–10 is described. The new building block diethyl 2,6-bis(bromomethyl)pyridine-3,5-dicarboxylate 1 was prepared and characterized. Single-crystal X-ray structure analyses indicate that these ribbon-like molecules arrange in a folded conformation, with the pyridine and benzene units being folded in a face-to-face manner, and the tosyl units of 8–10 pointing outwards. The “intramolecular self-assembly” (folding) of these molecular ribbons is primarily attributable to the energetically more favourable syn conformation of both the [3.3]metacyclophanes and the pyridinophanes.

Chemistry with Roataxanes: Intra- and Intermolecularly Covalently Linked Rotaxanes

The direct introduction of sulfonamide units (cf. 9) into carboxamide-based rotaxanes allows us to intramolecularly bridge the “wheel” and the “axle” of such species for the first time as is shown by the bridged bissulfonamide rotaxane 11. Due to its stronger acidity the SO2-NH proton can be selectively abstracted by mild bases even in the presence of CO.NH and then be substituted by treatment with suitable iodo compounds. This leads intramolecularly to 11 (71% yield) and intermolecularly to bis[2]rotaxane 16 (76% yield). The iodo-substituted rotaxane 15 isolated as a remarkably stable byproduct offers a new synthetic potential demonstrated by the preparation of 16.

Adamantan als Baustein neuer Araliphane Synthese, Spektroskopie und Kristallstrukturen

Adamantane as a Building Block of New Araliphanes – Synthesis, Spectroscopy, and Crystal Structures Exchange of benzene units for aliphatic building blocks in cyclophanes leads to new molecules of the “araliphane” type. With adamantane the araliphanes 2 – 4 are synthesized. Their stereochemical behavior as shown by NMR studies and X-ray crystallographic analyses differs significantly from that of their aromatic counterparts. The signals of the intraannular adamantane hydrogens are strongly shifted upfield up to δ=– 2.18 (in 2). 4 is obtained as a racemic mixture of enantiomers (in the crystalline state) and shows a boat-like deformation of the benzene moiety.

[3.3]Metacyclophane mit anti ‐Konformation

[3.3]Metacyclophanes with anti Conformation The [3.3]metacyclophanes 5 and 9 with prevailing anti conformation were prepared by using different cyclisation techniques. 1H-NMR studies and X-ray structure analyses of both phanes 5 and 9 prove their unprecedented conformations.

Synthesis and X-ray structure of amide-based macrocycles, catenanes and pretzelane

The syntheses and crystal structure studies of amide-based catenanes derived from m-phenylene diacrylic acid and 5-acetoxy isophthalic acid (17% and 3% yield of 4a and 4b resp.) and octalactam macrocycles (21% yield of 3) are described. Hydrogen bonding patterns play a key role in the formation of the different conformations of octalactam 3. The crystal structures of 3 reveal a number of hydrogen-bonding interactions between the macrocycle and two different solvent molecules, which are presumably responsible for the different conformations. Furthermore, we report the X-ray structure of a catenane, which was converted into a “pretzelane” by bridging two phenolic hydroxy groups with a p-xylyl…

Ein makrobicyclischer Tris-bipyridin-Ligand sowie ein Cu2I- und ein Ag3I-Komplex

Makrobicyclische Endorezeptoren: Synthese, Kristallstruktur und Einschluß organischer Gastmoleküle

Macrobicyclic Endoreceptors: Synthesis, Crystal Structure, and Inclusion of Organic Guests 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 1,10-phenanthrolines inside the cavity.

Binding of water and solvent molecules in a 25-membered-ring host compound

The macrocyclic 15- and 25-membered-ring pyridine oligomers 1 and 2 containing three and five methoxy substituents in the 4-position of the pyridine rings were prepared by Muller-Roscheisen cyclization and then isolated by chromatography. They are attractive as synthetic endobasic receptor molecules. X-ray structure analysis exhibits the inclusion of hydrogen-bonded solvent molecules (water and trichloromethane) inside the pentameric macrocycle 2.

Ultrafast Dynamics of Dansylated POPAM Dendrimers and Energy Transfer in their Dye Complexes

We have studied internal dynamics of dansylated poly(propyleneamine) dendrimers of different generations in solution and excitation energy transfer from dansyl chromophores to xanthene dyes that form van der Waals complexes with the dendrimers

The First Clamped and Strongly Deformed Adamantane

Das erste verklammerte und stark deformierte Adamantan

Repetitive‐Synthesis of Bulky Dendrimers – A Reversibly Photoactive Dendrimer with Six Azobenzene Side Chains

Dendrimers with bulky repeating units containing up to 43 benzene rings (in 9) have been obtained by using a repetitive divergent synthetic strategy (three generations). The new functional dendrimer 13 containing six azobenzene units at the periphery was synthesized allowing a reversible switching of the shape and size of the molecule upon irradiation. An X-ray structure analysis of the dendritic molecule 3a shows the inclusion of acetonitrile.

Ultrafast energy transfer in dansylated POPAM–eosin complexes

Abstract Excitation energy transfer (EET) in dendritic host–guest complexes has been studied. Three generations G2, G3 and G4 of dansyl substituted poly(propyleneamine) dendrimers (POPAM) were complexed with a fluorescent dye eosin in chloroform solution. Arrival of excitation from dansyls to eosin was monitored by femtosecond transient absorption spectroscopy. EET rates from the dansyls to eosin(s) are characterised by two time constants 1 ps and 6 ps independent of dendrimer generation. Relaxation processes in eosin were clearly faster when complexed with dendrimer than in solution. As several eosins are bound to G3 and G4 dendrimers, besides host–guest interaction, also eosin–eosin inter…

Homocalixpyridines: Ligands Exhibiting High Selectivity in Extraction and Sensor Processes

A novel spherical host architecture, based on pyridine subunits, has been created. It exhibits selective complexing properties toward soft metal ions (right), which have been tested in extraction and sensor processes. The complex-forming behaviour can be tailored by variation of the size of the cavity and by substitution. Homocalixpyridines are interesting in view of their application as selective carriers in separation and sensing techniques.

Calixarenes as Stoppers in Rotaxanes

The synthesis of the amide-based rotaxane 7a bearing calix[4]arene blocking groups is described for the first time. While rotaxane formation fails if a calix[4]arene is functionalized at the upper rim with only an amino or methylamino group lacking any spacer, the prolonged amine 5a works successfully as stopper unit preventing dethreading of the dimeric wheel 1a by its size. Rotaxane formation of 8b was observed only by MALDI-TOF mass spectrometry of the reaction mixture of the amine 5b, the axle 6 and 1a. With the larger trimeric wheel 1b no stable rotaxane could be obtained. It either does not act as a concave template or its opening is too wide, even for the bulky calixarene stoppers.

Internal dynamics and energy transfer in dansylated POPAM dendrimers and their eosin complexes.

Internal dynamics of dansylated poly(propyleneamine) dendrimers (POPAM, G1-G4) in solution and excitation energy transfer from dansyls to eosin in POPAM-eosin complexes have been studied by time-resolved fluorescence spectroscopy and molecular dynamics (MD) simulations. Combining the results from fluorescence anisotropy and the MD simulation studies suggests three time domains for the internal dynamics of the G3 and G4 generations, about 60 ps for motions of the outer-sphere dansyls, 500-1000 ps for restricted motions of back-folded dansyls, and 1500-2600 ps for the overall rotation. For the smaller generations, the contribution from the restricted motions was not entirely evident. Eosin bi…

Concave macrobicycles: Absorption spectra, luminescence properties, and endocavital complexation of neutral organic guests

By a mild modified Eglinton coupling a series of diynebridged macrobicyclic hosts capable of endocavital complexation were synthesized and their structures and complexation properties investigated by X-ray analysis. The inclusion of DMSO in 7 suggests a direct correlation between steric fit and orientation of the guest. On the basis of this hypothesis, the orientation of acetone in an endocavital inclusion of 2 was predicted and verified by X-ray analysis. Comparison of the single-crystal X-ray structures of the vacant macrobicycle 3 and of a family of macrobicycles showing endocavital or “pocket” complexation of neutral organic guests suggests that torsion of the cavities upon complexation…