Assembling the ligand

HOOK uses molecular skeletons , each with two or more connection points (specific bonds called hooks), and requires a free methyl group on each isolated fragment to be linked. If such a group exists, the fragment is connected 

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The activity of immobilized carbonic anhydrase on fully polymerized vesicles and no enzyme activity on unpolymerized vesicles clearly leads to the conclusion that cross-linking of the bilayers is a necessary step in the immobilization of enzymes on vesicle surface. Polymerization seemed to help in persevering the architecture and functionalities of organized assemblies. The ligand bound metal ions not only offer... 

Figure 43-11. The hormone response transcription unit. The hormone response transcription unit is an assembly of DNA elements and bound proteins that interact, through protein-protein interactions, with a number of coactivator or corepressor molecules. An essential component is the hormone response element which binds the ligand (A)-bound receptor (R). Also Important are the accessory factor elements (AFEs) with bound transcription factors. More than two dozen of these accessory factors (AFs), which are often members of the nuclear receptor superfamily, have been linked to hormone effects on transcription. The AFs can interact with each other, with the liganded nuclear receptors, or with coregulators. These components communicate with the basal transcription complex through a coregulator complex that can consist of one or more members of the pi 60, corepressor, mediator-related, or CBP/p300 families (see Table 43-6).

The ligand group can be introduced either on the meso or on the /5-pyrrole position of the porphyrin ring, but the synthesis of the meso-functionalized derivatives is easier and has been more widely exploited. Balch (50-53) reported that the insertion of trivalent ions such as Fe(III) (32) and Mn(III) (33) into octaethyl porphyrins functionalized at one meso position with a hydroxy group (oxophlorins) leads to the formation of a dimeric head-to-tail complex in solution (Fig. 11a) (50,51). An X-ray crystal structure was obtained for the analogous In(III) complex (34), and this confirmed the head-to-tail geometry that the authors inferred for the other dimers in solution (53) (Fig. lib). The dimers are stable in chloroform but open on addition of protic acids or pyridine (52). The Fe(III) octaethyloxophlorin dimer (52) is easily oxidized by silver salts. The one-electron oxidation is more favorable than for the corresponding monomer or p-oxo dimer, presumably because of the close interaction of the 7r-systems in the self-assembled dimer. 

Table 3 4x4 ligand matrix of aminopyridine (4a-d)/isoquinolone (5a-d) derived self-assembled bidentate ligands in the [Rh]-catalyzed hydroformylation of l-octenea... 

Supramolecular compounds are formed by treatment of silver salts and the ligand 4,5-ethyle-nedithio-l,3-dithiole-2-thione (C5H4S5), such as the polymeric chain [ AgfCd [4S5)3 Cl04-MeCN]2 or the 2D [Ag(C5H4S5)OTf]ra. All are assembled by S "S contacts.1 5... 

As a result of their low redox potentials [173], bis(phthalocyaninato) lanthanide complexes are often inadvertently reduced or oxidized, and they are also very sensitive to acids and bases. In order to solve these problems, Veciana et al. achieved certain success on designing a series of novel compounds with characteristics that would give them improved redox stability. Electroactive ligands based on phthalo-cyaninato tetra dicarboximide [175] or perfluorinated phthalocyanine [176] were used to assemble the double-decker lanthanide complexes, with the effect of stabilizing the negative charge of the anionic state of the compounds, which resulted in a strong shift of 0.7 V of their first oxidation potentials. 

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