The systematic synthesis of poly(phenylvinylene) (PPV) derivatives by the Wittig-Horner reaction is reported. The phenyl units of the PPV structure are methodically substituted by naphthyl and anthryl units to form a homologous series of structures. The 2,6 attachment of the vinylene linkage on the anthryl ring provides novel structures that have not been reported before due to their synthetic inaccessibility. The introduction of naphthyl units results in a hypsochromatic shift in the absorption and emission spectra, while the introduction of anthryl units leads to a bathochromatic shift relative to the naphthalene structures. The observed structural variation of the spectroscopic properties is explained in terms of a combination of the increased conjugation of the substituent acene units and the decreased electronic contribution across the vinyl linkage.
One of the enduring mysteries of nature is atom itself." Tony E why plants and animals that have two pos-rial College is mor sible mirror-image forms consistently opt for seems just too good one and not the other. Spiral-
Chemists report they've made the first nonspherical dendrimers—densely branched polymers that are usually in the shape of a ball. The new ones are shaped like rods, however, and that asymmetry may allow them to serve as liquid crystals (LCs): the hybrid molecules that flicker between solid and liquid states to form watch and computer displays. It's taken powerful electric fields to make polymers flicker like LCs in the past; the dendrimers flicker much more readily.
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