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RESEARCH PRODUCT

Untersuchungen zur Konformerenvielfalt von mono- und 2,5-dialkoxysubstituierten Poly(1,4-phenylenethenylen)en

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Investigations on the Conformational Variety of Mono- and 2,5-Dialkoxy Substituted Poly(1,4-phenyleneethenylene)s The alkoxy substituted poly(1,4-phenyleneethenylene)s 1 and 2 can principally exist in an enormous variety of conformers (table 1). However, force field calculations (MMX) reveal a far-reaching restriction to a relatively small number of non planar conformers with minimized steric energy. The decisive criterion is due to the interaction between the oxygen atoms and the olefinic hydrogens. An increasing steric hindrance should lead to higher twist angles θ in the main chain and hence to a shorter effective conjugation length. Such an effect could play a minor role between the unsubstituted parent compound and 1/2, but UV/Vis- and fluorescence spectra don't give any hints for a change of the effective conjugation length n ≈ 8 between 1 and 2.