Bis-Macrocycles

Enantiomerically pure cyclam-type ligands derived from L-proline have been prepared via multistep procedures and shown to form complexes of Ni11, e.g., (593).1508 The Ni11 ion in (594) is encapsulated by a face-to-face bis(macrocyclic) ligand that forms upon treatment of [Ni(tren)2]2+ with formaldehyde.1509... 

The denticity of the ligand compartments in bis(macrocyclic) Ni11 complexes can be increased by adding donor substituents to the macrocycles. For example, type (723) dinickel(II) complexes... 

EPR spectra of the dinickel(I) complexes (951)-(953) with bis(macrocyclic) ligands show that the two metals behave independently. 867... 

The 1,4,7-trithiacyclononane ligand, [9]aneS3, zinc complex was synthesized to compare with the electrochemistry of related complexes and showed an irreversible oxidation and an irreversible reduction at +1.30 V and —1.77 V vs. ferrocene/ferrocenium, and the X-ray crystal structure of the bis macrocycle zinc complex was reported.5 0,720... 

Surprisingly, on reacting [Fe(NCMe)e]2+ with unsaturated tetraaza-macrocycles similar to those described above, but containing 15 or 16 atoms in the ring, the two axially positioned acetonitrile molecules from the reagent become electrophilically bound to the apical carbon atom of the macrocycle giving rise to new, low spin, bis(macrocycle)hexadentate Fe(II) complexes, Scheme 11. 

Intramolecular Motion Within a Heterodinuclear Bis-macrocycle Transition Metal Complex... 

The bis-macrocyclic ring is positively charged because of the presence of Ni(II) and Cu(II). The crown ether and the bis-azamacrocyclic ring form a sandwich-like structure in such a way that one of the crown ether aromatic rings is located between the two metal-coordinated macrocyclic rings. The second aromatic ring is located almost parallel to the previous one outside the two linked macrocycles. 

Thus, for both the terminal diammonium and dicarboxylate substrates, selective binding by the appropriate receptors describes a linear recognition process based on length complementarity in a ditopic binding mode. Important biological species, such as polyamines, amino acid and peptide diamines, and dicarboxylates [4.18] may also be bound selectively. Recognition is achieved by multiple coordination to metal ions in dinuclear bis-macrocyclic coreceptors that complex selectively complementary bis-imidazole substrates of compatible length [4.21]. 

The validity of the MM-EPR method is further demonstrated with the two structurally related dicopper(II) complexes A and B whose calculated structures (MM-EPR) are presented in Fig. 9.6. For both bis-macrocyclic ligands two identical... 

Fabbrizzi, L., Montagna, L., Poggi, A., Kaden, T.A. and Siegfried, L.C. 1986. Ditopic receptors for transition metal ions a heterobimetallic nickel(II)-copper(II) bis(macrocyclic) complex and its stepwise oxidation to the tervalent state. Inorg.Chem., 25,2671-2672. 

A new family of crown-ether-based bolaamphiphiles, 21, that aggregate into a previously unknown type of bolaamphisome was prepared by Gokel and coworkers [50]. Evidence was presented on vesicle formation from the aqueous suspension of such bolaform amphiphiles. Several reports describing the synthesis of various macrocyclic models related to archael compounds have also appeared in the literature [51]. Fyles et al. prepared a novel series of asymmetric bis-macrocyclic bolaphiles, 22, and evaluated their transport activities in vesicles and planar bilayer membranes [52]. 

The synthesis of a bis-macrocycle (29) as the central core possessing two back-to-back rigidly connected 1,10-phenanthroline units was prepared from the macrocyclic dione 30 and act as "molecular handcuffs" as demonstrated by their two-step conversion to a bis-Cu(II) complex with 2,9-[di-p-(3-butenyloxyphenyl)]-l,10-phenanthroline, followed by a ringclosing metathesis reaction to give the desired catenane 31 <07CC4410>. 

Bis-macrocycles two macrocycles joined together Calixarenes basket-shaped macrocycles with phenyl backbones... 

Bis-macrocycles (10) provide another mechanism for achieving complexation of more than one metal ion. They are joined by a bridge linking two simple macrocycles. ... 

---