摘要
A highly distorted chiral nanographene structure composed of triple corannulene-fused[5]helicenes is prepared with the help of the Heck reaction and oxidative photocyclization with an overall isolated yield of 28%.The complex three-dimensional(3D)structure of the bowl-helix hybrid nanostructure is studied by a combination of noncontact atomic force microscopy(AFM)and scanning tunneling microscopy(STM)on the Cu(111)surface,density functional theory calculations,AFM/STM simulations,and high-performance liquid chromatography-electronic circular dichroism analysis.This examination reveals a molecular structure in which the three bowl-shaped corannulene bladesd position themselves in a C3-symmetric fashion around a highly twisted triphenylene core.The molecule appears to be shaped like a propeller in which the concave side of the bowls face away from the connected[5]helicene motif.The chirality of the nanostructure is confirmed by the direct visualization of both MMM and PPP enantiomers at the single-molecule level by scanning probe microscopies.These results underline that submolecular resolution imaging by AFM/STM is a powerful real-space tool for the stereochemical characterization of 3D curved chiral nanographene structures.
基金
Financial support from the Ministry of Education Singapore under the AcRF Tier 1(MOE T1 RG11/21)and AcRF Tier 2(MOE-T2EP10221-0002)
The Deutsche Forschungsgemeinschaft via grants(nos.SCHI 619/13 and EB535/1-1)
the GRK(Research Training Group)2204“Substitute Materials for Sustainable Energy Technologies”
the LOEWE Program of Excellence of the Federal State of Hesse(LOEWE Focus Group PriOSS“Principles of On-Surface Synthesis”)
the National Natural Science Foundation of China(grant nos.21790053,51821002,and 22072103)
the National Major State Basic Research Development Program of China(grant nos.2017YFA0205000 and 2017YFA0205002)
the Collaborative Innovation Center of Suzhou Nano Science&Technology
the 111 Project are also acknowledged for their financial support.
