A Study On The Aromaticity And Magnetic Properties Of N-confused Porphyrins

Aromaticity is one of the most basic and one of the oldest concepts in organic chemistry,dating back more than 200 years.Numerous criteria exist in the study of the aromaticity of compounds.At present,the aromaticity of organic compounds is determined by experimental and theoretical research methods.Aromaticity is predicted on the basis of the energetic,structural,magnetic,and electronic properties of a given system.Porphyrin is a general term for homologues and homologue derivatives with contain substituents and heteroatoms in the outer ring of porphine.Porphyrins and their related compounds exist widely in nature.Because of their unique physical and chemical properties,as well as their structure,porphyrins have good application prospects in the fields of medicine,material chemistry,synthetic chemistry,energy utilization,and performance materials.N-confused porphyrins are new and important photochemical materials and are being extensively used in a variety of fields due to their special photoelectric properties.Porphyrins have been studied extensively and great advancements have been made.In this paper,we determine the global aromaticity of N-confused porphyrins,N-confused porphyrazine and their derivatives,N-confused oxo-thio-porphyrins,N-confused oxoporphyrin,N-confused dioxoporphyrins,and dithioporphyrins by the use of the TRE and%TRE methods which are energetic criteria of aromaticity.The BRE and CRE methods were used to analyze the local aromaticity of these same compounds.The BRE and CRE results are compared with those obtained using other criteria of aromaticity as reported in the literature.Based on our BRE and CRE results,we have examined the contribution of 18?-electron main conjugation pathways to the global aromaticity of the molecule as a whole.RC is an important and reliable magnetic criteria of aromaticity.The strength of the magnetically induced RC is calculated using the Hückel-London model.The magnetic properties of all the compounds are analyzed using the RC method.The~1H-NMR chemical shifts as reported in the literature for the compounds studied here,are compared with the RC values we have calculated.Finally,the reason for the differing results produced by the TRE index and by the other indices are discussed.This paper consists of the following six chapters.In Chapter 1,the developmental history of the concept of aromaticity is discussed in detail.The methods used in this paper,including the TRE,BRE,CRE,and RC,are described and compared with other common criteria of aromaticity.Finally,the research significance of this paper is presented.In Chapter 2,we describe the global aromaticity of N-confused porphyrins using the TRE and TRE methods.The impact of the nitrogen atoms on global aromaticity is analyzed.The aromaticities of the different isomers relative to one another are explained according to the TCS rule.Using TRE and MRE,the trends in the aromaticity of these compounds is determined and then compared with the NICS(0)and relative energy results as reported in the literature.The local aromaticity of N-confused porphyrins is examined by means of the BRE and CRE methods.Based on the BRE and CRE results we obtained,the contribution of 18?-electron main conjugation pathways to the global aromaticity of the molecule as a whole is investigated.Finally,the magnetic properties of the compounds is studied using an RC model,and for the synthesized compounds,the correlation between the RC and the ~1H-NMR chemical shifts is analyzed.In Chapter 3,we describe the global aromaticity of porphyrazine using the TRE and MRE methods.Using TRE and%TRE,the global aromaticity of these porphyrazines is obtained and then compared with the NICS(0)and relative energy results found in the literature.The impact of the nitrogen atoms on global aromaticity is analyzed.The relative aromaticities of the different isomers are explained by means of the TCS rule.The local aromaticity of N-confused porphyrazines is examined using the BRE and CRE methods and then compared with normal porphyrin.Based on the BRE and CRE results we obtained,the contribution of 18?-electron main conjugation pathways to the global aromaticity of the molecule is investigated.Their magnetic properties are examined by the use of the RC method.In Chapter 4,the global aromaticity of N-confused oxa-thio-heteroporphyrins are studied using the TRE and MRE methods.The aromaticities of the different isomers in relation to each other are explained according to the TCS rule.Local aromaticity is studied by the BRE and CRE methods.Using the TRE and MRE methods,the trends in the aromaticity of these compounds is determined and then compared with the NICS(0)and relative energy results as reported elsewhere in the literature.Based on the BRE and CRE results we obtained,the contribution of 18?-electron main conjugation pathways to the global aromaticity of the molecule is investigated.Their magnetic properties are predicted using the RC method.In Chapter 5,the global aromaticity of multiple N-confused oxaheteroporphyrin is studied using the TRE,%TRE,and MRE methods.The relative aromaticities of the different isomers are compared and are explained according to the TCS rule.The results we obtained using the TRE,%TRE,and MRE methods are compared with those which have been reported by others in the literature.Local aromaticity is examined by the BRE and CRE methods.Based on the BRE and CRE results we obtained,the contribution of 18?-electron main conjugation pathways to the global aromaticity of the molecule is investigated.Finally,their magnetic properties are also predicted using the RC method.In Chapter 6,the global aromaticity of O-confused and S-confused heteroporphyrins is studied by means of the TRE,%TRE,and MRE methods.The local aromaticity is examined by the BRE and CRE methods.Based on the BRE and CRE results we obtained,the contribution of 18?-electron main conjugation pathways to the global aromaticity of the molecule is studied.The impact of oxygen and sulfur heteroatom substitution on the aromaticity of these compounds is investigated.Finally,the magnetic properties of the compounds is studied using the RC model,and for the synthesized compounds the correlation between the RC and the ~1H-NMR chemical shifts is analyzed.