A Study On The Aromaticity Of Polycyclic Compounds Containing Five-membered Ring(s)

The concept of aromatic is one of the most important and extensive research topics in organic chemistry.There are many experimental and theoretical studies to determine the aromatic properties and explain the reaction of the compounds.Compounds containing five-membered ring compounds,especially those containing heteroatoms in the five-membered ring,are often used as a core in natural products,compounds with drugs and biological activity,materials and so on,producing a series of substances.So many people are interested in their aromatic research.In this paper,the global aromatics of various possible isomers and derivatives of compounds containing five-membered ring were studied in detail by using the topological resonance energy(TRE)method.The local aromatic and kinetic stability of all possible isomers and derivatives of pyridine dithiophene and benzodithiophene were analyzed by bond resonance energy(BRE)method.This paper consists of the following parts:In chapter 1,the origin,development and several methods of judging aromatic are introduced systematically.The methods of this paper are used to discuss aromatic,including:BRE,TRE,CRE,RC and other methods,and with the common aromatic criteria for analysis and comparison.Finally,the significance of this paper is introduced.In chapter 2,the aromatic contribution of different types of chemical bonds to pyrene derivatives was analyzed by the BRE method.The effect of each circuit on the local aromaticity of the compounds was systematically investigated using circuit resonance energy(CRE).The global aromaticity of pyrene derivatives was investigated by TRE and percentage topological resonance energy(%TRE).In the literature,we conclude the aromaticity of the divalent anions and cations of these compounds with the conclusions of neutrality.In chapter 3,the aromaticity of the central ring is less than the six-membered ring on both sides.How does the aromaticity of the central six-membered ring change,or is it still in the middle?The aromatic strength of these compounds was discussed by calculation.In chapter 4,naphthalene is condensed with cyclopentadiene and benzene to form compounds including fluoranthene,cyclopenta[c,d]fluoranthene and so on.The BRE and CRE methods were used to study the local aromaticity of these materials and their divalent ions.We use TRE and%TRE and other methods to study their global aromaticity.Compared with the conclusion of VB resonance energy and total resonance and the main factors affecting the aromaticity are derived.In chapter 5,the local aromaticity and global aromaticity of the dithienopyridine and the dithiophene isomers is studied by bond resonance energy(BRE),circuit resonance energy(CRE)method and topological resonance energy(TRE).The calculated results show that the structure of six-membered ring has the greatest influence on the overall aromaticity of the compounds.In the dithienopyridine and dithiophene isomers series,the aromaticity is enhanced when a complete pyridine ring or complete benzene ring is present.On the contrary,it is weakened,and even the situation that the thiophene ring contributes to the overall aromaticity is large.In chapter 6,the global aromaticity of derivatives formed by acridine,9H-carbazole,dibenzofuran,and dibenzothiophene fused with one to four benzene rings was studied by TRE and%TRE,REPE,etc.Discussing BRE and the numerical value of CRE analyzes the source of aromaticity.