Synthesis and optical properties of isomeric branched pi-conjugated systems.
[structure: see text] Branched conjugated systems with a terminal alkyne function have been prepared starting from 4-(triisopropylsilylethynyl) phenylacetylene by applying the following iterative reaction sequence: (i) metal-catalyzed cross-coupling reaction of the terminal alkyne with 3,4-dibromobenzaldehyde or 2,5- dibromobenzaldehyde; (ii) Corey-Fuchs dibromoolefination and treatment with an excess of LDA. The building blocks thus prepared have been subjected to a Pd-catalyzed cross-coupling reaction with 1,4-diiodobenzene to yield isomeric branched pi-conjugated systems containing 7 (first generation) or 15 (second generation) phenyl units connected by ethynyl spacers. The different pi-conjugation patterns in those isomeric derivatives have a dramatic effect on their electronic properties, as attested by the differences observed in their absorption and emission spectra. Finally, theoretical calculations have been performed to rationalize the optical properties of these compounds.
Nierengarten
Jean-François
JF
Groupe de Chimie des Fullerènes et des Systèmes Conjugués, Ecole Européenne de Chimie, Polymères et Matériaux, Université Louis Pasteur et CNRS, 25 rue Becquerel, 67087 Strasbourg Cedex 2, France. jfnierengarten@chimie.u-strasbg.fr
Zhang
Sheng
S
Gégout
Aline
A
Urbani
Maxence
M
Armaroli
Nicola
N
Marconi
Giancarlo
G
Rio
Yannick
Y