A Study On The Aromaticity Of Acenes And Its Related Compounds

Acenes is one of the most important aromatic compounds. The global aromaticityof acenes and of their related compounds was examined using the topologicalresonance energy (TRE) and magnetic resonance energy (MRE) methods. Their localaromaticity was studied using bond resonance energy (BRE) and circuit resonanceenergy (CRE) methods. Moreover, their magnetic properties were studied employingthe circuit current (CC) and ring current (RC) methods. Finally， our RC results werecompared with the results reported in the literature.The main points of this thesis are outlined below:In chapter1the origins and development of concepts related to aromaticity arepresented. Several conventional indices of aromaticity，including geometric，energetic,and magnetic indices were introduced and compared. Their strengths and weaknesseshave been pointed out. Finally, the research significance of this paper is presented.In chapter2we have described the global aromaticity of phenacenes andhelicene using the TRE and MRE methods. The local aromaticity of phenacenes andhelicenes is examined by means of the BRE and CRE methods. The results weobtained are compared with those which have been reported by others in the literature.Their magnetic properties are analyzed using the CC and RC methods.In chapter3the global aromaticity of dihydrodiazapentacenes and theircorresponding4n+2π azapentacenes is examined using the TRE and MRE methods.The relationship between the aromaticity of the dihydrodiazapentacenes and thepositions at which nitrogen atoms substitute themselves into the corresponding4n+2πazapentacene skeleton has been discussed. Their local aromaticities are examined bythe BRE and CRE methods. Our CC and RC results are then compared with the NICSresults. We have identified a local aromaticity differential between the twosix-membered rings. In chapter4the global aromaticity of linear acenes and their BN-acenes is studiedby means of the TRE and MRE methods. The local aromaticities are examined usingthe BRE and CRE methods. Their magnetic properties are also examined using the CCand RC methods. Our results show that all these BN analogues exhibit loweraromaticity than their corresponding counterpart linear acenes.In chapter5the global aromaticity of triphenylene and its BN-substitutetriphenylene is studied by means of the TRE and MRE methods. Their localaromaticities are examined using the BRE and CRE methods. Their magneticproperties are also examined by the CC and RC methods. Our results here show thatthe both isomers display lower aromaticity than triphenylene, again in conformity withthe Clar π-sextet rule.