Spin‐dependent conduction and polarization in chiral polymers were studied for polymers organized as self‐assembled monolayers with conduction along the polymer backbone, namely, along its longer axis. Large spin polarization and magnetoresistance effects were observed, showing a clear dependence on the secondary structure of the polymer. The results indicate that the spin polarization process does not include spin flipping and hence it results from backscattering probabilities for the two spin states.
A rhodium‐based multicomponent catalytic system for well‐controlled living polymerization of phenylacetylenes has been developed. The catalytic system is composed of readily available and bench‐stable [Rh(nbd)Cl]2, aryl boronic acid derivatives, diphenylacetylene, 50 % aqueous KOH, and PPh3. This system offers a method for the facile and versatile synthesis of various end‐functionalized cis‐stereoregular poly(phenylacetylene)s because components from aryl boronic acids and diphenylacetylene were introduced to the initiating end of the polymers. The polymerization reaction shows a typical living nature with a high initiation efficiency, and the molecular weight of the resulting poly(phenylacetylene)s can be readily controlled with very narrow molecular‐weight distributions (Mw/Mn=1.02–1.09). The experimental results suggest that the present catalytic system has a higher polymerization activity than the polymerization activities of other rhodium‐based catalytic systems previously reported.
Spin‐dependent conduction and polarization in chiral polymers were studied for polymers organized as self‐assembled monolayers with conduction along the polymer backbone, namely, along its longer axis. Large spin polarization and magnetoresistance effects were observed, showing a clear dependence on the secondary structure of the polymer. The results indicate that the spin polarization process does not include spin flipping and hence it results from backscattering probabilities for the two spin states.
Ar hodium-based multicomponent catalytic system for well-controlled living polymerization of phenylacetylenes has been developed. The catalytic system is composed of readily available and bench-stable [Rh(nbd)Cl] 2 ,aryl boronic acid derivatives,d iphenylacetylene,5 0% aqueous KOH, and PPh 3 .T his system offers am ethod for the facile and versatile synthesis of various end-functionalized cis-stereoregular poly-(phenylacetylene)s because components from aryl boronic acids and diphenylacetylene were introduced to the initiating end of the polymers.T he polymerization reaction shows atypical living nature with ahigh initiation efficiency,and the molecular weight of the resulting poly(phenylacetylene)s can be readily controlled with very narrowm olecular-weight distributions (M w /M n = 1.02-1.09). The experimental results suggest that the present catalytic system has ahigher polymerization activity than the polymerization activities of other rhodium-based catalytic systems previously reported.
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