| Popis: |
Chiral polymers P - 1 and P - 2 were prepared by the polymerization of ( R )-3,3′-diiodo-2,2′-bisbutoxy-1,1′-binaphthyl (( R )- M - 1 ) and ( S )-3,3′-diiodo-2,2′-bisbutoxy-1,1′-binaphthyl (( S )- M - 1 ) with 2,5-bis[(4-tributylstannyl)phenyl]-1,3,4-oxadiazole ( M - 2 ) via Pd(PPh 3 ) 4 catalyzed Stille coupling reaction. 1,3,4-Oxadiazole unit not only has high electron affinity, high thermal and oxidative stability, but also serves as a good chromophore. Polymers have strong blue fluorescence due to the efficient energy migration from the extended π-electronic structure of the polymers to the chiral binaphthyl core and can be expected to have potential application in the materials of fluorescent sensors. Circular dichroism (CD) spectra of polymers P - 1 and P - 2 are almost identical except that they gave opposite signals at each wavelength. The long wavelengths CD effect of P - 1 and P - 2 can be regarded as the more extended conjugated structure in the repeating unit and a high rigidity of the polymer backbone. |
Full Text from ScienceDirect