title: Theoretical investigations on the geometric and electronic structures of phenylene-acetylene macrocycles.
abstract: The geometric and electronic structures of a series of conjugated macrocycles (phenylene-acetylene macrocycles, PAMs) have been studied theoretically with ab initio and semiempirical molecular orbital methods. The ab initio calculations at the HF/6-31G* level demonstrate that the model molecules may have a planar conformation. Bigger macrocycles, for example, 7PAM, 8PAM, and 9PAM, result in several energy minima. The boatlike conformation is the most energetically favored form. Based on the conformational analysis, a novel method for analyzing the ring-strain energy was proposed and used. In view of their potential applications as electronic materials, the electronic structures of a series of PAMs are also investigated. The LUMO-HOMO gaps of the planar PAMs show an odd-even difference behavior. In addition, the HOMOs of the planar species 3PAM, 5PAM, 7PAM, and 9PAM are doubly degenerated.
authors.affiliation: Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001, P R China.
authors.forename: Yanwei
authors.initials: Y
authors.lastname: Li
authors.forename: Jianwei
authors.initials: J
authors.lastname: Zhao
authors.forename: Xing
authors.initials: X
authors.lastname: Yin
authors.forename: Geping
authors.initials: G
authors.lastname: Yin
mesh_terms: D000114:Acetylene / Q000737:chemistry*; D001554:Benzene / Q000737:chemistry*; D004583:Electrons; D047028:Macrocyclic Compounds / Q000737:chemistry*; D008958:Models, Molecular; D008962:Models, Theoretical; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D047028:Macrocyclic Compounds; D001554:Benzene; D000114:Acetylene