Cage-like complexes

A cage-like complex results from the tris(imidazol-l-ylmethyl)benzene ligand in the presence of zinc acetate, [Zn3L2(OAc)6], and exhibits inclusion properties to neutral guest molecules in aqueous solution.134... 

Fujita, M., Nagao, S., Ogura, K., Guest-induced organization of a 3-dimensional palladium(II) cage-like complex - a prototype for induced-fit molecular recognition. J. Am. Chem. Soc. 1995, 117, 1649-1650. 

Several other silver(I) cage-like complexes have been reported.32-35 3,8,13-Tris (4-pyridyl methyl ami no)-2,7,1 2-tri methoxy-10,15-dihydro-5/7-tribenzo a,<7, ]... 

Figure 11.11. Ligands 5 and 6 used in the construction of silver cage-like complexes.

The above ligands are all rigid triangles with very little flexibility. However, Fujita and co-workers have developed an M3L2 cage-like complex by using the... 

Scheme 4-7. Branched routes of successive transformations resulting in cage-like complexes [Co(L872)] + to [Co(L875)] - formation of intermediate species (A) and (B).

Several models have been proposed to account for the non-random distribution of oligosaccharides formed when polysaccharides are hydrolysed by a-amylase. The preferred-attack model assumes that the probability of bond-cleavage depends on the position of the bond in the chain the repetitive (or multiple-attack) model assumes that a-amylase can form a cage-like complex with the substrate and attack it several times during a single encounter the multiple-enzyme (or dual-site) model assumes that the substrate is hydrolysed by the combined actions of exo- and en /o-enzymes. The effects of pH, inhibitors, and the chain length of the substrates have been studied in an attempt to decide which of the three models best fits the action of a-amylase. The effects of these variables on either the distribution of products or the action pattern of the enzyme were incorporated into the models, which were then used to interpret experimental data obtained with porcine pancreatic a-amylase. 

---