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Encyclopedia of Nanoscience and Nanotechnology Edited by H. S. Nalwa Volume 10: Pages (95-106)

The compounds 2a-c resemble in their structure the systems 1; however, they consist of (E,E)-1,4-distyrylbenzene building blocks [23,39]. Dendrimer 3a has, like 1 and 2, a threefold symmetry axis C3, and contains (E,E)-1,4-distyrylbenzene segments, as well as (E)-stilbene building blocks [40]. The same structural concept is realized in the series 4a-d [41, 42]; however, a nitrogen atom forms the center of the core.

In contrast to the three-arm systems 1-4 (l = 3), the dendrimers 5-7 have only two arms (l = 2), which are fixed in 5a-d [43, 44] on a benzene ring, in 6a [44] and 6b [44] on an anthracene, and in 7a [45] and 7b [45] on a chiral 1,1'-binaphthyl core. The stilbenoid dendrimers 8a [44] and 8b [44] are distinguished by four dendrons (l = 4) and a porphyrin core.

The dendrimers 1-8 are highly symmetrical, with two-, three-, or fourfold axes Cn. Compounds like 9a-d [19, 20], 10a, b [23, 39], and 11a-i [40, 44] can be regarded as den-drons, that is, as arms of special dendrimers, but they can also be regarded as less symmetrical dendrimers. The focal position in the central benzene rings can be occupied by different chromophores. The fullerodendrimers and their precursors 12a-f [46] and 12g-k [47, 48] deserve increasing attention. Finally, the methoxy-substituted compounds 12l and 12m belong to this series [24].

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