期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2022
卷号：119
期号：29
DOI：10.1073/pnas.2203701119
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Significance
Conjugated polymers have attracted great attention because of their promising physical properties. Aromatic moieties are often fundamental building blocks of conjugated polymer skeletons. Inclusion of transition metals, with their
d orbitals, into aromatic frameworks results in
d
π
–p
π conjugated metalla-aromatic systems, which have interesting physical properties. However, such metalla-aromatics have never been used as building blocks in the backbones of conjugated polymers. Herein, we report a polymerization reaction of alkynes and carbynes that affords metalla-aromatic conjugated polymers. This efficient stepwise polymerization involves consecutive carbyne shuttling processes. These metallopolymers not only are soluble and stable but also exhibit broad and strong ultraviolet absorption. It is anticipated that these
d
π–
p
π conjugated polymer systems will find applications in materials science.
Conjugated polymers usually require strategies to expand the range of wavelengths absorbed and increase solubility. Developing effective strategies to enhance both properties remains challenging. Herein, we report syntheses of conjugated polymers based on a family of metalla-aromatic building blocks via a polymerization method involving consecutive carbyne shuttling processes. The involvement of metal
d orbitals in aromatic systems efficiently reduces band gaps and enriches the electron transition pathways of the chromogenic repeat unit. These enable metalla-aromatic conjugated polymers to exhibit broad and strong ultraviolet–visible (UV–Vis) absorption bands. Bulky ligands on the metal suppress π–π stacking of polymer chains and thus increase solubility. These conjugated polymers show robust stability toward light, heat, water, and air. Kinetic studies using NMR experiments and UV–Vis spectroscopy, coupled with the isolation of well-defined model oligomers, revealed the polymerization mechanism.
