Interaction of N‐benzylamino(boronphenyl)methylphosphonic acid analogs with the gold colloidal surface under different concentration and pH conditions. (27th May 2014)

• Record Type: Journal Article
• Authors: Piergies, Natalia; Proniewicz, Edyta; Kim, Younkyoo; Proniewicz, Leonard M.; Moger, Julian; Radi, Peter
• Is Part Of: Journal of Raman spectroscopy. Volume 45:Number 7(2014:Jul.)
• Page Start: 581
• Page End: 590
• Publication Date: 2014-05-27
• Subjects: Raman spectroscopy -- Periodicals; 535.846
• DOI: 10.1002/jrs.4505
• Languages: English
• ISSNs: 0377-0486

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>In this study, we present surface‐enhanced Raman spectroscopy (SERS) investigations of five analogs of a novel group of <italic>N</italic>‐benzylamino(boronphenyl)methylphosphonic acids: <italic>N</italic>‐benzylamino‐(3‐boronphenyl)‐<italic>S</italic>‐methylphosphonic acid (<italic>m</italic>‐Ph<italic>S</italic>), <italic>N</italic>‐benzylamino‐(4‐boronphenyl)‐<italic>S</italic>‐methylphosphonic acid (<italic>p</italic>‐Ph<italic>S</italic>), <italic>N</italic>‐benzylamino‐(2‐boronphenyl)‐<italic>R</italic>‐methylphosphonic acid (<italic>o</italic>‐Ph<italic>R</italic>), <italic>N</italic>‐benzylamino‐(3‐boronphenyl)‐<italic>R</italic>‐methylphosphonic acid (<italic>m</italic>‐Ph<italic>R</italic>), and <italic>N</italic>‐benzylamino‐(4‐boronphenyl)‐<italic>R</italic>‐methylphosphonic acid (<italic>p</italic>‐Ph<italic>R</italic>) deposited onto 10‐nm gold nanoparticles in an aqueous solution at physiological pH (pH = 7). In addition, for the <italic>p</italic>‐Ph<italic>R</italic> molecule, the SERS spectra in the various conditions of pH levels of the solutions (from pH = 3 to 11) and phosphonic acid concentration (10<sup>−3</sup>–10<sup>−5</sup> M) were measured. In general, the SERS spectral profiles indicate that at pH = 7, all of the aforementioned molecules interact with the colloidal gold surface via a boronphenyl ring. However, the orientation of the boronphenyl ring onto the substrate surface is different for each of the studied molecules. The boronic acid group of <italic>p</italic>‐Ph<italic>S</italic> and <italic>p</italic>‐Ph<italic>R</italic> binds to the gold nanoparticles, whereas the phosphonic acid group assists in the interaction with the substrate for <italic>p</italic>‐Ph<italic>R</italic> only. For all the molecules, the –C<sub>L</sub>C<sub>α</sub>(P)N– fragment distinctly influences the molecule/gold interactions, especially in the case of <italic>o</italic>‐Ph<italic>R</italic>. The previous differences in the compound behavior at the gold/liquid interface underline the role of an absolute configuration (–<italic>R</italic> and –<italic>S</italic>) and a type of isomer (<italic>orto</italic>‐, <italic>meta</italic>‐, and <italic>para</italic>‐) on the SERS signals, which means their influence on the adsorbate geometry. Additionally, based on the SERS results for <italic>p</italic>‐Ph<italic>R</italic> in various environmental conditions, we draw conclusions about spectral changes (adsorbate geometry changes) as a result of the pH of solution and molecule concentration alternations. Copyright © 2014 John Wiley & Sons, Ltd.</p> </abstract>