Impact of Donor鈥揂cceptor Functionalization on the Properties of Linearly 蟺-Conjugated Oligomers: Establishing Quantitative Relationships for the Substituent and Substituent Cooperative Effect Based on

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• 作者：Elizabeth C. Varkey ; J眉rg Hutter ; Peter A. Limacher ; Hans P. L眉thi
• 刊名：Journal of Organic Chemistry
• 出版年：2013
• 出版时间：December 20, 2013
• 年：2013
• 卷：78
• 期：24
• 页码：12681-12689
• 全文大小：463K
• 年卷期：v.78,no.24(December 20, 2013)
• ISSN：1520-6904

文摘

To understand better the impact of donor鈥揳cceptor substitution on the properties of linearly 蟺-conjugated compounds, we performed a computational study on a series of variably substituted trans-polyacetylenes, polyynes, and polythiophenes. The focus of this work is on how rapidly the impact of a given substituent or a given combination of substituents vanishes along the 蟺-conjugated chain. The response of the structural (bond-length alternation, rotational barrier) and molecular properties ((hyper)polarizability, chemical shift) to substitution is analyzed using different protocols, including a superposition model for the evaluation of the cooperative effect of substituents in homo- and heterosubstituted oligomers. With the exception of the (hyper)polarizability, the impact of donor鈥揳cceptor substitution is found to vanish following an exponential. The rate of decay of the substituent impact is found to be characteristic for each backbone, whereas the choice of substituent determines the absolute value of the respective property. The combination of substituents is shown to determine whether the substituent cooperative effect on a property is of an enhancing or damping nature. The rate of decay of the cooperative effect on most properties, including the (hyper)polarizability, is also found to follow an exponential law.