Exponential Attenuation of Through-Bond Transmission in a Polyene: Theory and Potential Realizations

详细信息    查看全文

• 作者：Yuta Tsuji ; Ramis Movassagh ; Supriyo Datta ; Roald Hoffmann
• 刊名：ACS Nano
• 出版年：2015
• 出版时间：November 24, 2015
• 年：2015
• 卷：9
• 期：11
• 页码：11109-11120
• 全文大小：642K
• ISSN：1936-086X

文摘

An exponential falloff with separation of electron transfer and transport through molecular wires is observed and has attracted theoretical attention. In this study, the attenuation of transmission in linear and cyclic polyenes is related to bond alternation. The explicit form of the zeroth Green鈥檚 function in a H眉ckel model for bond-alternated polyenes leads to an analytical expression of the conductance decay factor 尾. The 尾 values calculated from our model (尾_CN values, per repeat unit of double and single bond) range from 0.28 to 0.37, based on carotenoid crystal structures. These theoretical 尾 values are slightly smaller than experimental values. The difference can be assigned to the effect of anchoring groups, which are not included in our model. A local transmission analysis for cyclic polyenes, and for [14]annulene in particular, shows that bond alternation affects dramatically not only the falloff behavior but also the choice of a transmission pathway by electrons. Transmission follows a well-demarcated system of 蟺 bonds, even when there is a shorter-distance path with roughly the same kind of 鈥渆lectronic matter鈥?intervening.