Amine species on self‐assembled monolayers of ω‐aminothiolates on gold as identified by XPS and NEXAFS spectroscopy

Abstract

Functionalised surfaces are of interest in many fields, e.g. in biomedicine, materials science and molecular electronics. In this study a series of self-assembled aliphatic and aromatic monolayers on gold substrates with terminal amino groups was investigated. Four different thiol molecules were used: aliphatic 11-aminoundecane-1-thiol (AUDT), aromatic 4-aminobenzenethiol (ABT) and aromatic ω-amino thiols with an alkyl spacer as 4-aminophenylbutane-1-thiol (APBT) and 3-(4 -amino-1,1 : 4 ,1 -terphenyl-4-yl)propane-1-thiol (ATPT). Evaluation of N 1s XPS data revealed that on the aromatic selfassembled monolayers (SAMs) amino groups exist preferentially as primary amines, whereas on the aliphatic SAM protonated and/or hydrogen-bonded amines are the major species. This result is crosschecked by N K edge near edge X-ray absorption fine structure (NEXAFS) spectroscopy and can be rationalised by the different basicity of aliphatic and aromatic amines. Copyright

Influence of polymerisation on the reversibility of low-energy proton exchange reactions by Para-Aminothiolphenol

“…The spectrum from the PATP reference presents only two contributions at 399.0 eV (~90% of the total nitrogen contribution) corresponding to primary amino groups (− NH2 ) and at 401.4 eV belonging to protonated or hydrogen-bonded amino groups ( NH3  + , H … NH2 ) 23–25 . It was already shown that amino groups are the dominating species for aromatic molecules whereas it can be the opposite for aliphatic amines 23,24 . Instead, polymerised samples presented four contributions, previously observed on polyaniline films 26–29 .…”

“…The line at 161.9 eV is attributed to thiol or thiolate strongly bonded to the gold surface 23,30–33 . The second doublet centred at 163.1 eV was previously ascribed to unbounded or non-chemisorbed thiol, thiolate or disulphide for high coverage 30,32,33 .…”

“…The second doublet centred at 163.1 eV was previously ascribed to unbounded or non-chemisorbed thiol, thiolate or disulphide for high coverage 30,32,33 . Two additional components are detected at 165.0 and 167.6 eV, attributed to the presence of oxidised sulphur species SO 2 − and SO 3 − (sulfinate and sulfonate) respectively 23,30,33 . Most of the S signal from the reference PATP sample is associated with bound thiol.…”

Effect of amino, hydroxyl, and carboxyl terminal groups of alkyl chains of self‐assembled monolayers on the adsorption pattern of gold nanoparticles

“…The chemical state of the nitrogen in the AUT‐SAM was revealed by high‐resolution N‐1 s spectra (Figure ). Two species were observed: one was attributed to amine (―NH 2 ) groups (399.9 eV), and the other was attributed to protonated (or hydrogen‐bonded) amino groups (401.7 eV) . The relative proportion of the protonated amines (77%) is relatively greater than that of the ―NH 2 amines (23%).…”

Using Directed Self Assembly of Block Copolymer Nanostructures to Modulate Nanoscale Surface Roughness: Towards a Novel Lithographic Process

“…Prior to treatment no significant nitrogen peak was observed, while after treatment with the block copolymer solution, peaks at 399 and 402 eV are clearly evident, which arise from the nitrogen‐containing PDMAEMA block and confirm the adherence of the block copolymer to the model surface. The peak at 399 eV is assigned to uncharged nitrogen atoms, while the peak at 402 eV is assigned to charged nitrogen atoms 70. Curve fitting of this region revealed that there was 79% uncharged and 21% charged nitrogen atoms.…”