P-quaterphenylenes

In the following the development is presented of a general approach for the synthesis of symmetrically and differently l,4" -substituted p-quaterphenylenes by application of a reliable Suzuki cross-coupling strategy. Experimental details are not given here but can be found elsewhere [51-53]. Note that organic synthesis is a key step for the bottom-up nanotechnology approach. 

Scheme 8.1 Synthesis of symmetrically 1,4 -disubstituted p-quaterphenylenes MOP4, CLP4, CNP4, NHP4, NMeP4, and NOP4 via Suzuki cross-coupling reactions (R = H or alkyl).

Scheme 8.3 Synthesis of nonsymmetrically 1,4 -idisubstituted p-quaterphenylenes MOCLP4, MOCNP4, and MONHP4 from a methoxy functionalized p-terphenylene (R = H or alkyl).

Scheme 8.4 Molecular formulas of 1-mono-functionalized p-quaterphenylenes MOHP4, CLHP4, and CNHP4.

The nonsymmetrically functionalized p-quaterphenylenes, however, behave differently [135]. 

Thus, it is possible to obtain tailored nanofibers from appropriately functionalized p-quaterphenylenes. A requirement for generating aligned nanofibers still seems to be muscovite mica as growth substrate, but the molecular basis is not restricted to p6P a para-phenylene molecular basis can be employed which tolerates functional groups at the para-positions. 

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