Helical oligomers

Apolar m-phenylene ethynylene oligomers 77 fold in apolar solvents, such as alkanes, into helices.117 Due to the strongly favored arene-arene interactions in this solvent type, the folding into a helical oligomer coincides with stacking of the folded oligomers into helical columnar polymers and a strong... 

We approached the problem of establishing a structure of the "random coil" conformation by first establishing the limits of the present computational model for a known polymeric structure, the a-helix. Coordinates, created by program MacroModel [22] for the carbonyl groups of a-helical oligomers were used, along with published and experimental dipole transition moments, to compute the VCD and absorption spectra of the a-helical conformer. We found that VCD spectra, independent of chain length, can be calculated for octamers, and that the choice of side chain residues is immaterial for the computed spectra. Both calculated and experimental data were normalized to one residue, to permit a comparison between computed and observed spectra. 

When an enantiopure menthyl-substituted monomer is first oligomerized, the resulting single-handed helical oligomer complex can be used as an enantioselective catalyst for the polymerization of achiral isocyanides. 

By changing the ratio of the meta- and para-linked building blocks, it should be straightforward to systematically tune the cavities of the corresponding crescent and helical oligomers. Such a strategy is seen in few natural or unnatural systems and is generally applicable to the creation of nanocavities of different sizes. 

Typical target assemblies of synkinesis are noncovalent dimers, charge-transfer complexes, hetero-dimers and -trimers, cyclic or helical oligomers, inherently asymmetrical or helical membranes in the form of vesicles, spheres, tubules, and rods, as well as macroscopic surface monolayers. Pores and domains in vesicle membranes and gaps of molecular size in surface monolayers are other synkinetic targets. They may function as receptors or reactive, enzyme-like surface clefts (Fendler, 1982 Fuhrhop 1982 Israelaehvili, 1992 Fuhrhop and Koning). 

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