Studies on circular dichroism behaviors of aggregated poly(1,4-phenylene)s with head-to-tail regioregularity

22 December 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Circular dichroism (CD) studies on poly(1,4-phenylene)s bearing a chiral side chain in the aggregated conditions were carried out. Little CD was observed in a solution form, while addition of a poor solvent into the polyphenylene solution induced aggregation and a strong CD was observed, accordingly. Applying the controlled degree of polymerization (DP) of poly(1,4-phenylene) in the use of bidentate diphosphine Chiraphos as a ligand for the nickel catalyst, the relationship of DP with CD strength was studied to reveal to show the highest CD at the DP = 84 (gabs = ca. 2 x 10–2). It was also found that the related aggregation was observed in good solvent 1,2-dichloroethane upon standing the solution at 4 °C for 3–23 days to observe gabs = ca. 10–1. Studies on the substituent effect of poly(1,4-phenylene) suggested that CD behaviors were dependent on the type of non-chiral substituent on the aromatic ring as well as the side-chain chirality.

Keywords

poly(14phenylene)
nickel catalyst
Chiraphos
CD
aggregation

Supplementary materials

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Supporting Information
Description
Experimental section, details on the characterization of poly(1,4-phenylene)s, and copies of NMR spectra. This material is available as PDF
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