Theoretical investigations on the geometric and electronic structures of phenylene-acetylene macrocycles. |
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Authors: | Yanwei Li Jianwei Zhao Xing Yin Geping Yin |
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Institution: | Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001, P R China. |
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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. |
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Keywords: | ab initio calculations electronic structure macrocycles molecular electronics semiempirical calculations |
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