Conceptual Developments of Aryldiazonium Salts as Modifiers for Gold Colloids and Surfaces

Abstract

Modified colloids and flat surfaces occupy an important place in materials science research due to their widespread applications. Interest in development of modifiers that adhere strongly to surfaces relates to the need for stability under ambient conditions in many applications. In the last 20 years, diazonium salts have evolved as the primary choice for modification of surfaces. The term 'diazonics' has been introduced in the literature to describe "the science and technology of aryldiazonium salt-derived materials". The facile reduction of diazonium salts via chemical or electrochemical processes, irradiation stimuli, or spontaneously, results in efficient modification of gold surfaces. Robust gold-organic nanoparticles and films modified by using diazonium salts are critical in electronics, sensors, medical implants, and materials for power sources. Experimental and theoretical studies suggest that gold-carbon interactions constructed via chemical reactions with diazonium salts are stronger than nondiazonium surface modifiers. This invited feature article summarizes the conceptual development of recent studies of diazonium salts in our laboratories and others with a focus on surface modification of gold nanostructures and flat surfaces, and their applications in nanomedicine engineering, sensors, energy, forensic science, and catalysis.

Designing the Surface Chemistry of Inorganic Nanocrystals for Cancer Imaging and Therapy

“…Knowing that CTAB is indispensable during gold nanorod synthesis, while it induces severe cytotoxicity, clearance of CTAB surfactant is always a key step for bio application of gold nanorods. Compared with thiol groups, aryldiazonium salts possess advantages such as higher stability under harsh conditions and better versatility of post functionalization [112].…”

New Trends in Nanoarchitectured SERS Substrates: Nanospaces, 2D Materials, and Organic Heterostructures

“…Diazonium and iodonium salts are now being used for the functionalization of plasmonic surfaces as alternatives to a thiol‐derived monolayer. [ 128 ] The reduction of aromatic diazonium salts (ADSs) allows the generation of reactive aryl radicals, which then attack the substrates forming a covalent bond (Figure 14b‐1). The covalent nature of metalC bond in the case of Au/Ag NPs has been demonstrated by Raman spectroscopy.…”

“…The attachment of ADS‐derived radicals can be performed spontaneously on noble metals and oxide or induced by stimuli such as acids/bases, heating, ultrasound, electrochemistry, and light, for example, in the case of 2D materials. [ 128,130 ] In contrast to noncovalent methods, diazonium chemistry provides overall control of the loading of organic functional groups via a variety of stimuli. The surface of 2D gold grating and optical fiber has been functionalized by spontaneous or electrochemical reduction using lipophilic ADSs with a long aliphatic chain for SERS sensing of cardiovascular disease markers [ 131 ] or water‐insoluble ibuprofen from wastewater.…”

“…Iodonium salts (ISs) are an appealing alternative to aromatic diazonium salts as they have a higher reduction potential which provides additional control over grafting [ 128b,139 ] (Figure 14b‐2). Gold‐coated optical fiber has been grafted with fluorinated groups using IS under plasmon excitation to provide antifouling properties for SERS sensing.…”

The Effect of Sibunit Carbon Surface Modification with Diazonium Tosylate Salts of Pd and Pd-Au Catalysts on Furfural Hydrogenation

“…Among all types of diazonium salts, arenediazonium tosylates can be considered as the most convenient reagents for the surface modification, due to their stability, inexplosive properties and good solubility in water [16]. Moreover, the arenediazonium tosylates have been widely applied for the surface modification of metal and carbon surfaces [17,18].…”