Abstract
Visible-light irradiation of phthalimide esters in the presence of the photosensitizer [Ru(bpy)3]2+ and the stoichiometric reducing agent benzyl nicotinamide results in the formation of alkyl radicals under mild conditions. This approach to radical generation has proven useful for the synthesis of small organic molecules. Herein, we demonstrate for the first time the visible-light photosensitized deposition of robust alkyl thin films on Au surfaces using phthalimide esters as the alkyl radical precursors. In particular, we combine visible-light photosensitization with particle lithography to produce nanostructured thin films, the thickness of which can be measured easily using AFM cursor profiles. Analysis with AFM demonstrated that the films are robust and resistant to mechanical force while contact angle goniometry suggests a multilayered and disordered film structure. Analysis with IRRAS, XPS, and TOF SIMS provides further insights.
Highlights
To accomplish thin film growth, Au(111) surfaces masked with mesospheres were immersed in solutions of phthalimide ester, benzyl nicotinamide, and the photosensitizer Ru(bpy)3Cl2 in CH3CN and irradiated for 30 min before rinsing/ultrasonication procedures
The resulting thin films on Au were subjected to Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and TOF SIMS analysis
The resulting thin films were subjected to contact angle goniometry and infrared reflectance–absorbance spectroscopy (IRRAS) analysis
Summary
The deposition of radical-derived organic thin films has emerged as an attractive alternative to the grafting of molecules such as thiols, chlorosilanes and alkoxysilanes [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28]. The most popular method for the deposition of radical-derived films involves the electrografting of arenediazonium salts [1,2,6,7,8,9,10,11,12,13,14,17,18,19,20].
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