The cage macrocycles

Cages derived from oxime precursors. In the initial synthesis of a cage (Boston Rose, 1968), tris(dimethylglyoximato)cobalt(m) [where dimethylglyoximato (dmgH) = (147)] was reacted with boron trifluoride 

A related procedure to that discussed for the tris-dmgH system has been employed to cap one end of Fe(n), Co(n), Ni(n) and Zn(n) complexes of the tripod ligand, tris(2-aldoxime-6-pyridyl)phosphine 

Two further unsaturated cages. Each of the systems discussed so far involves reaction of an electrophilic reagent with non-coordinated nucleophiles appended to metal-bound ligands. In contrast, in the following synthesis, cage formation occurs via an internal rearrangement of an Fe(u) complex of type (151) (Herron et al., 1982). Complexes of type (151) have already been discussed in Section 3.5. Treatment of these 

The interesting N6-case (154), incorporating three linked 1,10-phenan-throline moieties, has also been prepared as its sodium complex. An 

X-ray structure of this compound shows that the ligand adopts a propeller shape. The sodium ion is contained in the molecular cavity and is coordinated to all eight nitrogen atoms (Caron et al., 1985). 

---

Sepulchrates (7) are the most noted of the caged macrocyclic ligands and are the nitrogen analogs of the cryptands. The Co-N distances are 1.99 A for Co and 2.16 A for Co from crystallographic data, and do not vary greatly from other cobalt amines. ... 

The stability of cryptate complexes. The cage topology of the cryptands results in them yielding complexes with considerably enhanced stabilities relative to the corresponding crown species. Thus the K+ complex of 2.2.2 is 105 times more stable than the complex of the corresponding diaza-crown derivative - such enhancement has been designated by Lehn to reflect the operation of the cryptate effect this effect may be considered to be a special case of the macrocyclic effect mentioned previously. 

In order to increase structural diversity and to create a polar domain in the cage-like interior of these steroid/peptide macrocycles, dihydroxylated diacid 127 was synthesized in two steps from cholic acid (126) and reacted with diisonitrile 110, paraformaldehyde, and isopropylamine to form macrocycle 128 and its head-head isomer (Scheme 26). 

In order to construct a hydrophobic three-dimensional cavity that is in-tramolecularly limited in space, we have prepared cage-type cyclophanes by linking macrocyclic rings. First we prepared a macropolycyclic host, which is constructed with two rigid macrocyclic skeletons of different size, tetraaza[3.3.3.3]paracyclophane as the larger one and tetraazacyclotetradecane as the smaller one, and four flexible hydrocarbon chains that connect the two macrocycles [40]. The flexibility of four hydrocarbon chains connecting the two macrocycles allows the induced-fit host-guest interaction in aqueous media. 

Mixed-valent silver(I,II) compounds containing Ag2<22 To investigate the effect of coexisting metal ions on the assembly of polyhedral silver cages, macrocyclic (V-donor ligand 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane (tmc) has been used for in situ generation... 

Marchand et al. have reported the synthesis and X-ray structures of the cage-annulated oxa-thiacrown ethers 15 <2002JCX447>. Using these oxa-thiacrown ethers except for 15g and 15h, Williams et al. measured the electrospray ionization (ESI) mass spectrometry (MS) of the complexes with Hg2+, Pb2+, Cd2+, and Zn2+ cations <2002ANC4423>. All of the macrocycles in series bound the mercury ion very selectively and efficiently in the presence of many other metal ions. 

A metal ion encapsulated in the three-dimensional ligand cavity must be an acceptor bonded to the donor groups of all macrocycles forming the cage framework. This is time either when the metal ion size corresponds to the ligand cavity size or when the cavity can be transformed under the influence of the metal ion so that the distance between the central ion and the donor atoms of the cage is not over the sum of their ionic or covalent radii. In addition to the geometric parameters, the thermodynamic and kinetic stability of... 

---