Host-Gust Assembly Of Trichalcogenasumanene With Fullerene And Research On The Bridged D-A Structure

Bowl-shaped?-conjugated molecule is a kind of curved polycyclic aromatic hydrocarbons with open system,which has gained more and more attention as a part of the structure of fullerenes and carbon nanotubes.They can be used as not only template molecules for new materials but also precursor molecules for the synthesis of new materials.The different distributions of electronic cloud on the concave and convex surface makes the bowl-shaped?-conjugated molecules exhibit unique assembly characteristics and specific physicochemical properties.Most of the bowl-shaped?-conjugated molecules are derived from two subunits of fullerene:corannulene and sumanene.They can be applied in the fields of synthetic chemistry,coordination chemistry,supermolecular chemistry and optoelectronic materials due to thier outstanding properties.As the typical representative of bowl-shaped?-conjugated molecules,the depth of C_3vv symmetric sumanene is deeper than the C_5vv symmetric corannulene,so the ring tension is larger than the latter,which makes it more difficult to synthesis.Untill 2003,sumanene were successfully synthesized by Japanese scientists Sakurai et al,which promoted its subsequent development.In view of the breakthrough in the synthesis of sumanene,scientists began to focus their attention on the heterasumanenes.On the one hand,the introduction of heteroatoms can modulated the energy level of electrons by the difference of electronegativity,on the other hand,the stacking mode of molecules can be changed by the interaction between heteroatoms.In 2014,by using HBT as the starting material,our group simply and efficiently obtained the sumanen derivatives in which benzyl was replaced by sulfur atom and selenium atom through ring cyclizationandringcontraction,andachievedthegram-stagepreparationof trichalcogenasumanenes firstly.Based on this research,firstly,we shortened the butoxy at the periphery of trichalcogenasumanenes,obtained co-crystals containing sumanene and fullerene.The host-guest assembly of trichalcogenasumanenes and C₆₀0 was realized.Secondly a series of oxazole-fused trichalcogenasumanenes were prepared,and a series of trichalcogenasumanene-fullerene dyads were achieved on the basis of oxazole-fused trichalcogenasumanenes.The photoelectric properties of this series of compounds were further studied.Chapter 1,literature review,the research background of buckybowls is expounded,then the representative buckybowls and its applications in synthetic chemistry,supermolecular chemistry and optoelectronic materials are introduced.Finally,we explained the design idea of this thesis.Chapter 2,Supramolecular assembly of Trichalcogenasumanenes with Fullerenes.Based on2,3,6,7,10,11-hexa?1-butoxy?trichalcogenasumanenes,the peripheral alkyl chain of the molecule was tailored by dealkylation-substitution to obtained trichalcogenasumanenes substituted with different alkoxy groups?methoxy,ethoxy and propoxy?.It has been discovered that the length of the alkoxy group has an great influence on the stability of the complex composed of such bowl-shaped molecules and fullerenes.The methoxy-substituted trichalcogenasumanenes have good crystallinity.At the same time,it can form a stable host-guest assembly with fullerenes.In this assembly system,the methoxy-substituted selenium atom hybrid sumanene can form a quasi-one-dimensional"D-A"type co-crystal with the fullerene(C₆₀,C₇₀).In the co-crystal,two bowl-shaped molecules enclose a C₆₀/C₇₀0 in a"sandwich"manner,and the molecule is transformed from a planar configuration to a bowl-shape configuration.Chapter 3,Structural fusion of trichalcogenasumanene and fullerene.Based on the selective oxidationproducttrichalcogenasumaneneortho-quiones,aseriesofoxazole-fused trichalcogenasumanenes was obtained by condensation with benzaldehyde compounds.Trichalcogenasumanene-C₆₀0 dyads was synthesized by Prato reaction,in which electron-rich trichalcogenasumanene and electron-deficient C₆₀0 were bridged through a benzene ring.The theoretical calculation results showed that the HOMO are completely distributed on the sumanene structure,while the LUMO are completely distributed on the C₆₀0 unit,and the two orbits are completely separated.The energy band gap of dyads is significantly reduced compared with the original trichalcogenasumanenes,which indicates that the electron can easily transfer from the donor moiety to the acceptor moiety and form an excited state.Femtosecond transient spectroscopy studies have found that the electron-rich trichalcogenasumanenes and the electron-deficient C₆₀0 in the dyads could produce the light-induced charge transfer phenomena,the charge separation state can be rapidly formed under the irradiation of the laser.Chapter 4,The main contents of this thesis are summarized,and the future work is prospected.