Dendritic molecule first-generation

The first-generation dendrimer 51 was directly observed by transmission electron microscopy (TEM). The TEM image showed that the dimensions of individual molecules are about 50 A, which is consistent with the calculated one [36]. Third-order NLO measurements showed a significant enhancement of two-photon absorption upon proceeding from the constituent molecules to the dendritic complex [35]. 

FIGURE 5.42 Chemical structures of first-generation (42) and second-generation (43) self-immolative, receiver-amplifier dendritic molecules with an enzymatic trigger (blue), cleaved by PGA and 6-aminoquinoline (red) reporter groups. 

Hyperbranched and dendritic macromolecules have recently been the subject of considerable interest. Bolm developed chiral hyperbranched macromolecules 57 that catalyzed the enantioselective addition of diethylzinc to benzaldehyde [75]. The enan-tiocontrol of the hyperbranched chiral catalysts was slightly lower than for the low-molecular-weight catalyst. TADDOLs linked with dendritic molecules have been synthesized [59]. For example, use of the first generation dendrimer 58 with six terminal TADDOL units resulted in high enantioselectivity. 

The bis-porphyrin forms a cleft which, after complexation with Zn(II), acts as a receptor for a,o>-diaminoalkanes. For example 1,12-diaminododecane is bound with an association coiLstant of K. = 7.0 x 10 mol L. When a first-generation dendritic polyamine bearing four terminal primary amine groups is used as a guest, two receptor molecules assemble in such a way that they encapsulate the small dendrimer molecule, as in 50 (Figure 28). This was proven by titration studies, using H NMR and UV-vis absorption spectroscopy. 

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