Imidazole/carboxylate-donor ligand

Fig. 69 (top) Structure of bimido ligand and (bottom) preorganized mixed imidazole/ carboxylate-donor ligand. 

All reported trinuclear manganese-oxide complexes possess the so-called basic carboxylate structure (Fig. 17) (62, 301-303). The three metals are disposed in a triangle with a central /z3-oxide in (or approximately in) the Mn3 plane two carboxylates bridge each pair of Mn, while the last coordination site on each metal is filled by a terminal donor ligand such as pyridine, imidazole, or water. This arrangement... 

The 2-hydroxypropyl 4-nitrophenyl phosphate (HPNP) transesterification reactivity (Fig. 40, bottom) of binuclear zinc complexes of the dianionic ICIMP and trianionic BCIMP ligands (Fig. 62) have been compared.245 Notably, both of these ligands contain imidazole and carboxylate donors akin to protein-derived residues that are found as ligands to the zinc centers in phosphate-ester-hydrolyzing enzymes such as phosphotriesterase. The initial rate for HPNP transesterification promoted by [(ICIMP)Zn2(Ph2Ac)]C104 in 50% acetonitrile-water solution (tris buffer) was determined to be five times faster than the reaction promoted by [(BCIMP)Zn2(Ph2Ac)]. 

Some other naturally chiral carboxylate ligands were also selected to construct chiral MOFs. For example, assemblies of Zn " and Cd " with o-camphoric acid in combination with some semi-rigid N-donor auxiliary ligands, such as 1,3- and l,4-bis(imidazol-l-ylmethyl)benzene and 4,4 -dipyridylsulfide, result in the formation of chiral MOFs [M(l,3-bimb)(D-ca)] (M = Zn, Cd), [Zn(l,4-bimb)(D-ca)] and a noncentrosymmetric MOF [Cd2(dpys)(D-ca)2(H20)2] H2O , in which the ID Zn (Cd )/D-ca chains are linked by N-donor ligands to form either a 2D network or a ladder-like structure [21]. Preliminary experimental results indicate that they exhibit SHG intensities ca. 0.3, 0.1, 0.3, and 0.8 times, respectively, as large as that of urea. In fact, many MOFs with nonaromatic chiral ligands are... 

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