Syntheses And Properties Of Carbon Nanotube Fragments Based On Different Polycyclic Aromatic Hydrocarbons

Carbon nanotubes(CNTs)have become one of the most potential materials in electronics and energy chemistry field due to their superior mechanical,optical and electronic properties.However,the low purity and difficult separation of mixed CNTs in the existing preparation methods have seriously hampered its further development of fundamental studies and advanced applications.To precisely control the chemical structures of CNTs,the bottom-up approach using template molecules is one of the ideal strategies to synthesize CNTs with high purity.Cycloparaphenylenes(CPPs)and cyclacences can be regarded as the shortest segments of armchair and zigzag CNTs,respectively,making them as excellent templates for bottom-up synthesis of CNTs.Since the first synthesis of cycloparaphenylenes in 2008,CNTs fragments represented by CPPs have become a research hotspot in organic materials and synthetic chemistry.In this thesis,four kinds of CNTs fragments based on different PAHs units were studied as follows:1.Octamethoxy-[8]CPP(OMe-[8]CPP)with highly symmetrical struture was synthesized by template methods based on platinum complex.Octamethoxy-[8]CPP exhibited different photophysical properties from unsubstituted[8]CPP,as explained by theoretical DFT calculations.In addition,the photoinduced electron transfer process between octamethoxy-[8]CPP and a receptor molecule was systematically investigated.This multifunctionalized CPP structure has important role in the construction of new carbon nanoring structures,and provides a more valuable molecular precursor for subsequent studies.2.Synthesis and properties of carbon nanorings with different number of phenanthrene units([n]cyclo-2,7-phenanthrenylenes)by organoplatinum-mediated method and reduction elimination reaction.[n]Cyclo-2,7-phenanthrenylenes exhibited the size-dependent properties in terms of 1H NMR,fluorescence spectra and fluorescence quantum yields.Furthermore,the supramolecular interaction between[5]cyclo-2,7-phenanthrenylenes and fullerene C60 was tentatively explored,and their 1:1 complexation was proved.The success synthesis of[n]cyclo-2,7-phenanthrenylenes can provide the basis for the development other ?-conjugated polycyclic aromatic hydrocarbon-based carbon nanorings.3.A conjugated coronal macrocyclic molecule embedded with three phenanthrene was obtained by the Diles-Alder reaction of the phenanthreneethynylene macrocycle with 2,5-dimethyl-3,4-diphenylcyclopenta-2,4-dienone.This coronal macrocyclic molecule can be considered as a new fragment of armchair(6,6)CNTs.This synthesis strategy provides a simple bottom-up synthesis route for CNT fragments with a high yield.Furthermore,this molecule exhibited supramolecular interaction with fullerene C60,and a 1:1 complexation was studied.This synthetic method could be used to construct other new CNTs fragments.4.Synthesis and properties of a novel three-dimensional capsule-like carbon nanocage,tripodal-[2]HBC,whereby three L-shaped diphenylcyclohexane monomers were used to connect two HBC caps.This nanocage was successfully achieved by Pd-mediated coupling reaction and subsequent aromatization of the cyclohexane moieties,which is a fragment of capped(12,0)CNTs.This molecule also exhibited supramolecular interaction with fullerene C70,and and their 1:1 complexation was confirmed by various physical characterizations.This present method for construction of the nanocage provides a rational route for the bottom-up construction of end-capped zigzag CNTs.