Design,Synthesis And Properties Of "H" Type Of Anthracene Derivatives And Its Photoexcited State

Anthracene is one of the simplest acene with three linear fused benzene rings,which can be used as building blocks for organic materials due to its synthetic accessibility and ease of operation.Accordingly,anthracene and its derivatives are widely used in organic electronics such as field effect transistors,solar cells,light emitting and etc.Despite the great progress in the development of anthracene derivatives,selective modification of the 1-,4-,5-and 8-positions of the anthracene core is not easy due to the lack of stereoselective sites.Notably,the [4+4]photodimerization reaction of anthracene is one of the first discovered photochemical reactions by chemists.This reaction exhibited reversibility under controllable conditions.However,the photodimerization of anthracenes usually encounter limited light-wavelength range and substrates,and possibly complicated stereomers as dimeration products,which makes the photodimerization unclear and difficult to large-area application.In this thesis,we have rationally designed and synthesized1,8-dibromo-4,5-bis(trifluoromethanesulfonate)anthracene,which bearing bromine and trifluoromethanesulfonate functional groups with different reactivities toward coupling reactions.By using it as starting material,“H”-type anthracene derivatives with four aryl alkynes attached at 1-,4-,5-and 8-positions of π-core were afforded.The main contents were shown as following:(1)We developed an efficient method to prepare1,8-dibromo-4,5-bis(trifluoromethanesulfonyl)anthracene,even on a large scale(kilogram scale)in the laboratory.With this compound,two "H"-type anthracene derivatives decorated with four aryl alkynes were successfully synthesized by a rational coupling reaction.These two derivatives were named Sym-ANT and Asym-ANT,respectively.’Sym’ stands for symmetrical and ’Asym’ stands for asymmetrical anthracene,because of the different aryl alkyl groups attached.Their molecular structures and topologies were characterized by NMR,mass spectrometry and single crystal diffraction analysis.It was found that these compounds have high fluorescence quantum yields in both solid and solution states,which may be attributed to the absence of significant intermolecular π-π interactions.In addition,the Asym-ANT compounds show carrier transport properties.(2)The photodimerization of both compounds was investigated by using NMR hydrogen spectroscopy and UV-Vis spectroscopy under light excitation at 470 nm.Notably,Sym-ANT shows a clear and complete photodimerization reaction,while Asym-ANT produces multiple isomers,probably due to its asymmetric structure.In contrast to the fluorescence quenching observed during the photoreaction of most anthracene derivatives,both compounds exhibit a change in the fluorescence color of the photodimer upon visible light irradiation,due to the intense blue emission of their photodimer products.This difference may be due to the inhibition of the nonradiative decay channels through spatial interactions and the rich hydrogen bonding interactions between molecules,thus making the radiative decay of the excited state the dominant de-excitation mode.In addition,the thin films of both compounds are capable of effective photodimerization.This is because there are only weak hydrogen-bonding interactions between molecules and no strong π-π stacking and other interactions,resulting in molecules in a loose state,which facilitates conformational transitions during photodimerization under thin films.(3)On the basis of "H"-type anthracene precursor,we proposed a synthetic way to construct boron-doped coronene.This conjugated π-system might have a novel annulene-within-annulene structure,which the possible physical properties are preditced by us.