Surface Functionalization and Patterning by Multifunctional Resorcinarenes

Plant phenolic compounds and catecholamines have been widely used to obtain substrate-independent precursor nanocoatings and adhesives. Nevertheless, there are downsides in using such phenolic compounds for surface modification such as formation of nonuniform coatings, need for multistep modification, and restricted possibilities for postfunctionalization. In this study, inspired by a strong binding ability of natural polyphenols found in plants, we used three different macrocyclic polyphenols, known as resorcin[4]arenes, to modify the surface of different substrates by simple dip-coating into the dilute solution of these compounds. Eight hydroxyl groups on the large rim of these resorcin[4]arenes provide multiple anchoring points to the surface, whereas the lower rim decorated with different appending groups introduces the desired chemical and physical functionalities to the substrate's surface. Deposition of a uniform and transparent resorcinarene layer on the surface was confirmed by several surface characterization techniques. Incubation of the modified substrates in different environments indicated that the stability of the resorcinarene layer was dependent on the type of substrate and the pH value. The most stable resorcinarene layer was formed on amine-functionalized substrates. The surface was modified with alkenyl functional groups in one step using a resorcinarene compound possessing four alkenyl appending groups on its small rim. Thiol-ene photoclick chemistry was used to site-selectively postfunctionalize the surface with hydrophilic and hydrophobic micropatterns, which was confirmed by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. Thus, we demonstrate that resorcin[4]arenes extend the scope of applications of plant polyphenol and mussel-inspired precursors to tailor-made multifunctional nanocoatings, suitable for a variety of potential applications in biotechnology, biology, and material science.