Nuić Laura, Senkić Ana, Car Željka, Asić Ena, Vujičić Nataša, Kralj Marko, Biljan Ivana
Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102A, HR-10000 Zagreb, Croatia.
Center for Advanced Laser Techniques, Institute of Physics, Bijenička cesta 46, HR-10000 Zagreb, Croatia.
Langmuir. 2025 Feb 11;41(5):3066-3077. doi: 10.1021/acs.langmuir.4c03274. Epub 2024 Dec 9.
Disulfide-containing nitrosoarenes with [bis(4-nitrosobenzyl) disulfide, ()] or without [4-nitrosophenyl disulfide, (), and 1,2-bis(4'-nitroso-[1,1'-biphenyl]-4-yl)disulfane, ()] an alkyl spacer between the sulfur headgroup and the aromatic moiety (phenyl in () or biphenyl in ()) were synthesized and used as precursors to form azodioxy thiolate films on Au(111) substrates. Due to the incorporated disulfide functionalities, these specifically designed nitrosoarenes are enabled to self-polymerize through azodioxy bonds on a gold surface. Thin films of (), (), and () were prepared at different adsorption times via the solution-phase self-assembly of molecules onto the Au(111) surface and characterized by Raman spectroscopy, ellipsometry, water contact angle measurements, atomic force microscopy (AFM), and scanning tunneling microscopy (STM). For comparison, films of structurally analogous disulfide-containing nitro derivatives on Au(111), which can form only monolayer films, thus serving as a reference, were also fabricated and characterized. Raman spectra of (), (), and () films on the Au(111) substrates revealed the presence of a N═N stretching band of the -azodioxy group. Ellipsometry showed that nitrosoarenes form thicker films compared with their nitro counterparts, indicating the formation of azodioxy oligomer films. AFM revealed an island-like morphology of the nitrosoarene films, in contrast to the rather homogeneous one observed for the monolayer films of nitro derivatives. STM images of nitrosoarene films indicated the formation of poorly organized surface structures in which oligomer chains are possibly interdigitated and substantially tilted relative to the surface normal, which agrees with the relatively low values of the ellipsometry-derived thicknesses. The obtained results emphasized the influence of the substituent electronic effects on the on-surface formation of azodioxides and could be used for the future design of azodioxy thiolate films on gold surfaces.
合成了含二硫键的亚硝基芳烃，其中[双(4-亚硝基苄基)二硫醚，()]带有或[4-亚硝基苯基二硫醚，()，以及1,2-双(4'-亚硝基-[1,1'-联苯]-4-基)二硫烷，()]在硫端基与芳族部分( ()中的苯基或()中的联苯)之间有一个烷基间隔基，并用作在Au(111)基底上形成偶氮二氧基硫醇盐薄膜的前体。由于引入了二硫键官能团，这些经过特殊设计的亚硝基芳烃能够通过金表面上的偶氮二氧基键进行自聚合。通过分子在Au(111)表面的溶液相自组装，在不同吸附时间制备了()、()和()的薄膜，并通过拉曼光谱、椭偏仪、水接触角测量、原子力显微镜(AFM)和扫描隧道显微镜(STM)对其进行了表征。为了进行比较，还制备并表征了在Au(111)上结构类似的含二硫键硝基衍生物的薄膜，这些薄膜只能形成单层膜，因此可作为参考。Au(111)基底上()、()和()薄膜的拉曼光谱显示存在-偶氮二氧基的N═N伸缩带。椭偏仪显示，与硝基类似物相比，亚硝基芳烃形成的薄膜更厚，这表明形成了偶氮二氧基低聚物薄膜。AFM显示亚硝基芳烃薄膜呈岛状形态，这与硝基衍生物单层膜观察到的相当均匀的形态形成对比。亚硝基芳烃薄膜的STM图像表明形成了组织不良的表面结构，其中低聚物链可能相互交错并相对于表面法线大幅倾斜，这与椭偏仪测得的相对较低的厚度值一致。所得结果强调了取代基电子效应对偶氮二氧化物表面形成的影响，可用于未来金表面偶氮二氧基硫醇盐薄膜的设计。
