Synthetic Approaches to Regioregular Unsymmetrical Dialkoxy-Substituted Poly(1,4-phenylene ethynylene)s

Abstract

Poly(2,5-disubstituted-1,4-phenylene ethynylene)s, PPEs, are generally synthesized by Pd-catalyzed coupling polymerizations of appropriately substituted 1,4-diiodobenzenes and 1,4-diethynylbenzenes (i.e., condensation polymerization of A-A and B-B type monomers). If the monomers are not symmetrically substituted, this results in an irregular substitution pattern of the side chains along the polymer backbone. As with other classes of conjugated polymers, the relative placement of side chains along the backbone should influence the properties of the materials. We report a new synthetic approach to prepare regioregular unsymmetrically substituted PPEs by polymerization of 4-iodophenylacetylenes (i.e., a condensation polymerization of a single A-B type monomer). We have synthesized both the regiorandom and regioregular PPEs from unsymmetrically substituted monomers. We provide a detailed discussion of various approaches to the synthesis of PPEs with different regioregularities and provide a preliminary description of the differences between regioregular and regiorandom analogues.

Synthesis and Characterization of Poly(5,8-quinoxaline ethynylene)s

“…Elemental analyses were performed by Atlantic Microlab, Inc. (Norcross, Georgia). 4,7- Dibromobenzo[c][1,2,5]thia-diazole, 1,4-bis(dodecyloxy)-2,5-diethynylbenzene and 1,4-bis(dodecyloxy)-2,5-diiodobenzene , were prepared by previously reported procedures. Synthetic prodecures and characterization of homologues a ( R = 4-(2-ethylhexyloxy)phenyl) are provided below.…”

Defining side chain successions in anthracene-based poly(arylene ethynylene)-alt-poly(phenylene vinylene)s: probing structure–property relationships

“…The regiospecific functionalization of aryl derivatives requires a sufficient electronic differentiation of the ring positions. 41,42 The reaction of 1a with 4-toluenesulfonyl chloride provided the intermediate 10a. The tosyl group reduces the electron density at the ortho-positions significantly, leading to a strong deactivation for electrophilic attacks.…”

Poly(aryleneethynylene)s

“…However, when employing a monomer bearing an A-B reactivity pattern and dissimilar side chains, regioregularity is necessitated. Recently, this effect was probed by Collard and coworkers using dissimilar linear alkoxy side chains and found to influence solid-state electronic structure and molecular packing [23]. It still remains to be seen whether regioregularity will be as important to PAEs as it has been to polythiophene (refer to Chapter 3).…”