Para-Fluoro-Thiol Reaction on Anchor Layers Grafted from an Aryldiazonium Salt: A Tool for Surface Functionalization with Thiols

Abstract

A new coupling reaction, the para-fluoro-thiol (PFT) reaction, activated by base at room temperature, is reported for carbon surface functionalization. 4-Nitrothiophenol (4-NTP) and (3-nitrobenzyl)­mercaptan (3-NBM) were coupled to pentafluorophenyl (F5-Ph) anchor layers grafted from the aryldiazonium ion formed in situ. The relative yields of the PFT reactions, estimated from the electrochemical responses of coupled nitrophenyl (NP) and nitrobenzyl (NB) groups, depended on the nucleophilicity of the thiolate and the strength of the base. The highest surface concentration (4.6 × 10–10 mol cm–2) was obtained using 3-NBM in the presence of [Bu4N]­OH; this concentration corresponds to the maximum that is typically achieved for other high-yielding coupling reactions at aryldiazonium ion anchor layers. The PFT reaction is expected to be applicable to the numerous thiol derivatives commonly restricted to self-assembled monolayer (SAM) formation at gold and other noble metals, thereby opening a simple new approach for interface design on carbon substrates. The strategy may also have advantages for modification of gold surfaces: the layer prepared by coupling 3-NBM to F5-Ph films on gold was found to be more stable to storage under ambient conditions than self-assembled monolayers of 3-NBM.

Self-Assembled Monolayers for Interfacial Engineering in Solution-Processed Thin-Film Electronic Devices: Design, Fabrication, and Applications

“…72,244 By XPS, elements not contained in the substrate are usually selected as references, such as the P element in PA anchors, 72,289 metals in complex functional groups, 167 the S element in conjugated functional groups and sulfhydryl groups, 166,169,177 and halogens in structural modification. 153,272,290 Usually, the peaks of the elements in the substrate can be clearly distinguished in the XPS spectra, which directly proves the ultrathin structure of the SAM. 56 Tu et al developed a SAM molecule with 9,10-diphenyl anthracene (PA-2PhAn) 190 with the aggregation-induced emission enhancement (AIEE) properties.…”

“…It can identify the composition and content of surface elements by the positions and intensities of photoelectrons and the chemical environment by signal splitting. The identified signals prove the presence of the elements, and thus the existence of the SAM molecules. , By XPS, elements not contained in the substrate are usually selected as references, such as the P element in PA anchors, , metals in complex functional groups, the S element in conjugated functional groups and sulfhydryl groups, ,, and halogens in structural modification. ,, Usually, the peaks of the elements in the substrate can be clearly distinguished in the XPS spectra, which directly proves the ultrathin structure of the SAM . Tu et al developed a SAM molecule with 9,10-diphenyl anthracene (PA-2PhAn) 190 with the aggregation-induced emission enhancement (AIEE) properties.…”