Construction Of Sulfur-Embedded Pentacene Based On Perylene Building Block

In recent years,polycyclic heteroaromatic molecules with diverse structures and excellent properties have attracted more and more attention.They exhibit numerous intriguing properties,such as two-dimensional conjugated structures,anti-aromaticity,and redox.Such materials have great potential applications and can be used as functional platforms to develop conjugated materials such as novel fluorescent agents,NIR dyes,charge transfer agents,and organic magnetic molecules.The future development of this field is likely to be driven by the continuous search for novel structural motifs.Therefore,based on the pentacene systems,we develop a novel sulfur-embedded pentacene conjugate structure based on twisted perylene,aiming to gain a deeper understanding of pentavirenoids.In this study,two novel sulfur-embedded pentacene derivatives were successfully prepared by fusing benzothiophene units with a perylene core functional molecule as the parent,and the differences in physical properties,electronic structures,and solid stacking were compared,and the differences in aggregation conjugation patterns caused by molecular isomerism were found.In addition,the ionic compounds of sulfur-embedded pentacene molecules were further synthesized by chemical oxidation,and their radical properties and electronic structure characteristics were investigated.The specific researches are as follows.（1）Two types of functional perylene based sulfur-embedded pentacene molecules（syn-BBDP and anti-BBDP）were prepared from two isomers of per-2Br by Suzuki coupling reaction and Scholl dehydrocyclization reaction.It was found that the two types of molecules have the same chemical composition and very similar physical properties in the solution state,however,their molecular solid-state characteristics are quite different,such as distinguishable crystal colors and crystalline molecular configurations.As a result,we propose the difference in the conjugation mode of the aggregated state molecules.（2）The dicationic compounds(syn-BBDP²⁺and anti-BBDP²⁺)of functional molecules of sulfur-embedded pentacene were obtained by chemical oxidation using AgSbF₆ as a single-electron oxidant.Experiments and theoretical calculations revealed that the ground-state electronic structure of the dication is a singlet diradical.On this basis,we propose the formation mechanism of the diradical electronic structure,that is,the strong antiaromaticity weakens theπ-electron bonding and forms an unpaired and highly delocalized cationic radical.（3）Using sulfur-embedded pentacene functional molecules as model compounds,we investigated the carrier mobility of the isomeric molecules and their differences by combining theoretical calculations and crystalline properties,and explored the potential of the two types of compounds as organic semiconductor materials.