Synthesis of porphyrin-end-functionalized poly(p-phenylene) as a leaf-green-colored soluble semiconducting polymer: Control of π-π interactions for visible-light absorption

摘要

The synthesis of tetraphenylporphyrin (H_2TPP)-end-functionalized poly(p-phenylene) (H_2TPP-PPP) as a leaf-green-colored soluble semiconducting polymer with a well-controlled and defined polymer chain structure was achieved for the first time. Chloromethyl-end-functionalized poly(1,3-cyclohexadiene) (CM-PCHD) was prepared by the living anionic polymerization of 1,3-cyclohexadiene and the post-polymerization reaction of poly(1,3-cyclohexadienyl)lithium and chloro(chloromethyl)dimethylsilane. H_2TPP-end-functionalized PCHD (H_2TPP-PCHD) was then prepared by the addition of 5-(4-hydroxy-phenyl)-10,15,20-triphenylporphyrin to CM-PCHD. The dehydrogenation of H_2TPP-PCHD with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone was performed under ultrasonic irradiation, and H_2TPP-PPP was obtained as a target polymer in almost quantitative yield. The -Si(CH_3)_2-CH_2-O- bond in H_2TPP-PPP effectively inhibited the coordination of the H_2TPP end-group onto the PPP moiety, and the aggregation of H_2TPP-PPP with the accumulation of the H_2TPP end-group was formed. H_2TPP-PPP exhibited a leaf-green color and had a very broad absorption band overlapping the visible-light region, similar to chlorophyll a.