Processable Rylene Diimides up to 4 nm in length: Synthesis and STM Visualization
作者单位：Max Planck Institute for Polymer Research Department of Chemistry KU Leuven-University
会议名称：《2015年第十四届全国应用化学年会》
会议日期：2015年
学科分类：081704[工学-应用化学] 07[理学] 08[工学] 0817[工学-化学工程与技术] 070303[理学-有机化学] 0703[理学-化学]
关 键 词：Rylene Diimides Organic semiconductors Scanning tunneling microscopy
摘 要：Our group has reported the syntheses of terrylene, quaterrylene,pentarylene, and hexarylene diimides over the past two decades. To achieve good solubility, four bulk alkylphenoxy groups were introduced at the bay positions. However, this method has two limitations: 1) the steric repulsion between the substituents at the bay positions causes a serious twist of the conjugated core and thus obstructs the intermolecular interactions;2) electron-rich phenoxy groups greatly raise the LUMO energy level, and hamper the role of RDIs as n-type semiconductors. To overcome these drawbacks, we designed and synthesized soluble hexarylene diimides(HDI) and octarylene diimides(ODI) with planar conjugated cores which are as long as 2.87 and 3.74 nm respectively. HDI(λ = 908 nm, ε = 256000 M)cm) shows intense NIR absorption in the range of 700-1000 nm. The absorption of ODI(λ = 1007 nm, ε = 79800 Mcm) is the range of 400-1400 nm. Electrochemical properties of HDI and ODI were investigated by cyclic voltammetry, and the LUMO energy is-3.95 eV and-3.94 eV respectively, which indicates strong electron accepting ability of the two compounds. Scanning tunneling microscopy(STM) reveals that HDI, after deposition from solution, forms a unique herringbone bilayer or stable multilayers depending on the concentration at the liquid–solid interface. We also found a simple and efficient method to fabricate well-aligned thin films of HDI over a few millimeter squares. The strategy involves use of capillary force in a two-step flow method to induce large area alignment of multilayers of molecules at the organic liquid-solid interface.