Roemer Max, Gillespie Angus, Jago David, Costa-Milan David, Alqahtani Jehan, Hurtado-Gallego Juan, Sadeghi Hatef, Lambert Colin J, Spackman Peter R, Sobolev Alexandre N, Skelton Brian W, Grosjean Arnaud, Walkey Mark, Kampmann Sven, Vezzoli Andrea, Simpson Peter V, Massi Massimiliano, Planje Inco, Rubio-Bollinger Gabino, Agraït Nicolás, Higgins Simon J, Sangtarash Sara, Piggott Matthew J, Nichols Richard J, Koutsantonis George A
Chemistry, School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, United Kingdom.
J Am Chem Soc. 2022 Jul 20;144(28):12698-12714. doi: 10.1021/jacs.2c02289. Epub 2022 Jun 29.
This paper describes the syntheses of several functionalized dihydropyrene (DHP) molecular switches with different substitution patterns. Regioselective nucleophilic alkylation of a 5-substituted dimethyl isophthalate allowed the development of a workable synthetic protocol for the preparation of 2,7-alkyne-functionalized DHPs. Synthesis of DHPs with surface-anchoring groups in the 2,7- and 4,9-positions is described. The molecular structures of several intermediates and DHPs were elucidated by X-ray single-crystal diffraction. Molecular properties and switching capabilities of both types of DHPs were assessed by light irradiation experiments, spectroelectrochemistry, and cyclic voltammetry. Spectroelectrochemistry, in combination with density functional theory (DFT) calculations, shows reversible electrochemical switching from the DHP forms to the cyclophanediene (CPD) forms. Charge-transport behavior was assessed in single-molecule scanning tunneling microscope (STM) break junctions, combined with density functional theory-based quantum transport calculations. All DHPs with surface-contacting groups form stable molecular junctions. Experiments show that the molecular conductance depends on the substitution pattern of the DHP motif. The conductance was found to decrease with increasing applied bias.
本文描述了几种具有不同取代模式的功能化二氢芘（DHP）分子开关的合成方法。5-取代间苯二甲酸二甲酯的区域选择性亲核烷基化反应为制备2,7-炔基功能化的DHP开发了一种可行的合成方案。文中还描述了在2,7-位和4,9-位带有表面锚定基团的DHP的合成。通过X射线单晶衍射对几种中间体和DHP的分子结构进行了阐明。通过光照射实验、光谱电化学和循环伏安法对这两种类型的DHP的分子性质和开关能力进行了评估。光谱电化学结合密度泛函理论（DFT）计算表明，从DHP形式到环二烯（CPD）形式存在可逆的电化学开关现象。在单分子扫描隧道显微镜（STM）断结中结合基于密度泛函理论的量子输运计算对电荷传输行为进行了评估。所有带有表面接触基团的DHP都形成了稳定的分子结。实验表明，分子电导取决于DHP基序的取代模式。发现电导随外加偏压的增加而降低。
