Oligophenylene rods

D.M., Beck, P.A. and Strongin, R.M. (2000) Convenient iterative synthesis of an octameric tetracarboxylate-functionalized oligophenylene rod with divergent end groups. Organic Letters, 2, 3201 1. 

Oligophenylene rods [92, 112] have attracted much interest as spacers [113], because of their thermal and photochemical stability, and their interesting tunable photophysical properties. Until recently their use as bridging ligands was limited to species containing only one or two phenylene units (see compounds 23-26, Figure 8) because of synthetic difficulties related to solubility problems [24, 33, 74, 97, 114-117]. 

This approach has been successfully applied to various polyaryls. For example, the s)mthesis of oligophenylene rods is shown in Eq. 62. " ... 

The trimethylsilyl (TMS) or bromo group in the quaterphenyl is converted into the corresponding boronic acid by either of the procedures shown in Eq. 6, which allows further cross-coupling to synthesize oligophenylene rods. 

Figure 19 Zipper assembly on gold surface. The sequential binding of compounds 50-53 allows building interdigitated NDI stacks coaxially arranged with arrays of oligophenylene rods.

For wire-type compounds, very attractive candidates to play the role of spacers are polyenenes, polyalkynylenes, oligothienylene, oligophenylenes. In our laboratory we have recently prepared [23a] the rod-like compound N-(ph)5-A (overall length 3.1 nm. Figure 9a), where a 1-naphthyl (N-) and a 9-anthryl (-A) chromophoric units are connected by a 1,4-quinquephenylene-type spacer [-(ph)5-] bearing alkyl chains for solubility reasons. We have found that in N-(ph)5 A the practically complete quenching of the fluorescent excited states of the naphthalene- and... 

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