Synthesis, Structure, Chromatic Properties, and Induced Circular Dichromism of Polydiacetylenes with an Extended Conjugated System in the Side Chain

Abstract

We synthesized PDAs with a 4‐carboxyphenyl substituent directly connected to the conjugating main chain in order to investigate the effects of the side chain structure on the chromatic properties of the polymers. A series of 1,3‐alkadiynyl‐4‐benzoic acids (m,Ph‐DA‐CO2H) and their 1‐naphthylmethylammonium salts (m,Ph‐DA‐Naph) were prepared and polymerized under UV and γ‐ray irradiation. The resulting poly(m,Ph‐DA‐CO2H)s had absorption bands in their UV‐vis spectra in a wavelength region longer than those for the poly(m,Ph‐DA‐Naph)s and the other PDAs. We report the first example of the induced circular dichromism of poly(m,Ph‐DA‐CO2H) in the combination with a chiral (1‐cyclohexyl)ethylamine in the dispersion and in the solid state by an acid/base interaction.magnified image

Acetylenic Polymers: Syntheses, Structures, and Functions

“…The prerequisite to realize this attractive potential is to establish versatile processes for synthesizing the polymers. This has motivated many research groups all over the world to work on the exploration of acetylene-based polymerization reactions. − As a result, a large variety of acetylenic polymerization reactions have been developed, especially after the ground-breaking work of Shirakawa, MacDiarmid, and Heeger in the 1970s …”

“…Much work has been done to understand the structural issues, and various approaches have been taken to control or modulate the macromolecular structures, such as the design of molecular structures of alkyne monomers, the search for stereospecific or regioselective catalyst systems, and the optimization of polymerization conditions or parameters (Scheme ). An appreciable portion of these structural investigations has been carried out in combination with the studies of materials properties of the polymers, in an effort to collect information on and gain insights into the structure−property relationships involved in the acetylenic polymer systems. − …”

“…The property investigations have not only shed light on the structure−property relationships but also led to the development of specialty polymers with advanced functionalities. − Because the driving force for the acetylenic polymer research in the early days was to generate π-conjugated polymers with electronic activity, much of the early work had been devoted to the development of highly conductive materials. Since the ene, yne, enyne, diyne, phenyl, and triazole units in the acetylenic polymers are rich in π-electrons, the electronic communications between these units governed by the effective conjugation lengths in the polymer chains or spheres result in the formation of “dynamic” chromophores with varied optical and photonic responses.…”

Single Crystal to Single Crystal Polymerization of a Self-Assembled Diacetylene Macrocycle Affords Columnar Polydiacetylenes

“…They consist of a chain of alternating ene–ynes that show sensitivity to environmental conditions including temperature, pH, host–guest interactions, and solvent. PDAs display a relatively low band gap (∼ 2.0 eV). − Bulk PDA films display fast photoconduction properties and large nonlinear responses and are amenable to doping, which dramatically increases their conductivity. − Because of their remarkable environmental sensitivity, PDAs have been incorporated into peptide nanostructures, − helical polymers, − liquid crystals, , thin films, − and sensors. − …”

Structural and Chromatic Changes of Host Polydiacetylene Crystals during Intercalation with Guest Alkylamines

“…Nevertheless, intercalation proceeds with a high efficiency to achieve a high conversion. The PDAs are also one of the promising candidates as the polymer host compound for organic intercalation because they have a lamellar structure similar to the polymers obtained from 1,3-diene monomers …”