Jimmy Bouchard

Molecular design of chromic functionalized conjugated polymers

The thermochromic and solvatochromic properties of a series of polyphenylenes and polyfluorenes have been investigated experimentally and theoretically. For instance, poly[1,4-(2,5-dioctyloxyphenylene)-2,5-thiophene], poly[1,4-(2,5-dioctylphenylene)-2,5-furan] have revealed interesting chromic effects which, on the basis of calculations on dimer model compounds, seem to be related to a rather flexible backbone with an energy barrier against planarity of < 1,3 kcal/mol. However, in the absence of sterically demanding side chains (e.g. poly[1,4-(2,5-dioctyloxyphenylene)-2,5-furan) ], the conjugated polymer can maintain a highly conjugated (co-planar or nearly co-planar) conformation, even at high temperatures or in dilute solutions, Also, as observed with poly[1,4-(2,5-dioctylphenylene)-2,5-thiophene], if the steric interactions are too strong, no co-planar conformation can be adopted upon cooling or aggregation. Finally, a comparative table shows the minimum energy angle and energy barrier against planarity of various repeat units which could help in the rational design of chromic polymers.

Synthesis of N‐Octyl‐2,7‐dimethoxy‐1,8‐bistrimethylsilyl‐3,6‐dibromocarbazole

Abstract Starting with 2,7‐dimethoxycarbazole, a N‐alkyl‐hexafunctionalized carbazole derivative has been synthesized in only three steps with a good overall yield. N‐Octyl‐1,8‐bistrimethylsilyl‐3,6‐dibromo‐2,7‐dimethoxycarbazole is a new synthon that could be useful for the synthesis of conjugated polymers or bioactive compounds.