Indenofluorene-based Gridochemistry And Their Organic Nanounits

The construction of covalent nanostructure systems containing?-conjugated units is one of the basic work in the field of organic optoelectronics.Their special molecular structure and potential properties make them have great application prospects in this field.In recent years,the discovery of the fluorene-based nanogridarenes?NGA?system is one of the typical representatives.The fluorene-based nanogridarenes has obvious advantages such as unique molecular rigidity,regular geometry,abundant scalability and easy molecular modification,so they were widely used in organic semiconductor devices.However,fluorene-based nanogridarenes also have an inevitable shortcoming,that is,many isomers are difficult to separate,which limits their development.This is because when the two fluorenyl units are connected by a covalent single bond,the conformation is not stable enough,and a certain degree of spatial distortion will be caused when constructing the nanogridarenes and its intermediates,resulting in the formation of multiple isomers.Therefore,this paper proposes to use indeno[2,1-a]fluorene as a building block to reduce the appearance of isomers,and to use superelectrophiles strategies to construct two new types of indenofluorene-based semi-gridarenes and gridarenes systems.Starting with covalent nanostructure units,this paper introduces the development of macrocyclic compounds and fluorene-based nanogridarenes,and summarizes the research progress of indenofluorene and superelectrophilic chemistry.The specific research contents and conclusions are as follows:First of all,two indenofluorenol were synthesized efficiently,and their Friedel-Crafts with thiophene,carbazole under the condition of non-super acid such as BF₃.Et₂O,Fe Cl₃ was investigated.It is found that the main product obtained is the U-shaped structure in which the carbazole 3 position or the thiophene?position connected to the indenofluorene sp³ carbon,rather than the expected nanogridarene.This is because in the U-shaped structure,the two sp³ carbon-linked groups of indenofluorene are located on different sides of the skeleton plane,so they cannot further close the ring.Subsequently,by adding superacid HBF₄·Et₂O at room temperature,making indeno[2,1-a]fluorene produce superelectrophiles with two positive charges to activate the thiophene?position,and through intramolecular ring closure to obtain trans semi-grid structure linked with thiophene?position and indeno[1-a]fluorene sp³ carbon,and subjected to NMR analysis,single crystal data analysis,theoretical calculations and photophysical analysis,etc.,so as to fully reveal the structure and properties of this new molecule.At the same time,the reaction mechanism was also studied in detail,that is,the thiophene?-position ring-closing reaction involving superelectrophiles.Finally,by reducing the reaction temperature and taking advantage of the superelectrophilic properties of indeno[2,1-a]fluorene under super-acid conditions and related intramolecular forces,the cis nanogridarene of?-thiophene position linked with indeno[2,1-a]fluorene sp³ carbon were obtained,and NMR analysis,single crystal data analysis and reaction path analysis were carried out to understand the relevant characteristics of nanogridarene molecules as deeply as possible.In addition,the reaction mechanism was studied,that is,by controlling the temperature,concentration and reaction time,and using the superelectrophile to activate the thiophene?position,the kinetic product indenofluorene-based nanogridarenes was constructed.In this paper,the synthesis of indeno[2,1-a]fluorene thiophene semi-grid and grid nanoarenes with regular structure,single isomer,and strong expandability both innovates the method of?-position ring closure of thiophene,making up the fluorene-based arene isomers which are difficult to separate,also enriched the types of fluorene-like arene,and laid a solid foundation for its subsequent application in the field of organic optoelectronics.