# Aqueous-Organic Phase Transfer of Gold and Silver Nanoparticles Using Thiol-Modified Oleic Acid
## 3 Results  
### Preparation of Thiol Terminated Oleic Acid (OAS)  
Infrared spectra were recorded for OA and thiol-terminated oleic acid (OAS). Figure 2 show the infrared transmission spectrum of (a) OA; (b) 2-aminoethanethiol; and (c) OAS. The IR spectra of OA and OAS indicate that the 2-aminoethanethiol is indeed part of the composite. In the infrared transmission spectrum of pure oleic acid, the infrared band at 1707 cm\({}^{-1}\) is related to C=O stretching mode. Generally, COOH groups involve hydrogen bonding at higher concentrations to form the dimeric COOH species. Upon hydrogen bonding, the band location for the C=O stretching modeinvolving the monomeric COOH species shifts to a lower wavenumber due to the perturbation of the vibrational mode. The weak shoulder at 1656 and 1245 cm\({}^{-1}\) can be attributed to the C=C stretching mode for oleic acid and C-O stretching, respectively. Finally, the infrared band at 1434 cm\({}^{-1}\) is related to C-OH in-plane bending [20; 21]. For the infrared analysis of 2-amoniethanethiol, the infrared band at 2780 cm\({}^{-1}\) is related to N-CH\({}_{2}\) stretching. IR bands at 1131, 1150, and 1175 cm\({}^{-1}\) are ascribed to aliphatic C-N stretching, the IR bands at 750 and 758 cm\({}^{-1}\) are attributed to NH wagging and twisting, and the 660 IR band is associated with C-S stretching. Finally, the IR band at 2494 is attributed to S-H stretching [20]. In the infrared transmission spectrum of OAS, the infrared band at 3260 cm\({}^{-1}\) is attributed to secondary amide N-H stretching. The 1650 cm\({}^{-1}\) band is attributed to secondary amide C=O stretching, and 1556 cm\({}^{-1}\) can be attributed to secondary amide N-H bending and C-N stretching. Finally, the infrared band at 642 cm\({}^{-1}\) is related to C-S stretching. As is presented, OA modification to obtain OAS was carried out successfully due to the disappearance of the 2780 cm\({}^{-1}\) band related to N-CH\({}_{2}\) stretching and the consequent appearance of one band at 1556 cm\({}^{-1}\), which can be attributed to secondary amide N-H bending and C-N stretching.  
The resulting signals for NMR \({}^{1}\)H and NMR \({}^{13}\)C for OAS are presented in Figure 3. Move it down. Signals for \({}^{1}\)H NMR -CH\({}_{2}\)SH and -N-CH\({}_{2}\) were found at \(\delta_{\rm H}\) = 2.90 (2H, s, H-21) and 3.41-3.66 (2H, d, H-20). While signals for equivalent methylene protons CH=CH- were found at \(\delta_{\rm H}\) = 5.31 (1H, s, H-9 and H-10), signals for alkylic protons of oleic acid chain are at \(\delta_{\rm H}\) = 0.99-1.5 (22H, m, H2-7, H12-15) and \(\delta_{\rm H}\) = 1.5-1.75 (6H, m, H-15 and H-16). Finally, protons -CH\({}_{2}\)- were found at \(\delta_{\rm H}\) = 1.75-2.0 (6H, m, H-8, H-11 and H-17). Mercapto proton signal was found overlapped \(\delta_{\rm H}\) = 1.21 (1H, s, H-22), terminal -CH\({}_{3}\) was found at \(\delta_{\rm H}\) = 0.85 (2H, s, H-1) (Figure 3a). The corresponding signals for \({}^{13}\)C NMR, shown in Figure 3b, are CH\({}_{2}\)-SH (26.92, C-21), NH-CH\({}_{2}\)-(57.28, C20), -CH\({}_{2}\)C=O (38.65, C17), NHC=O (180.26, C18), -CH\({}_{2}\)-(22.40, C2), -CH\({}_{2}\)-(24.79, C16), -CH\({}_{2}\)-(28.86, C6 and C13), -CH\({}_{2}\)-(29.03, C15), -CH\({}_{2}\)-(29.24, C5 and C14), -CH\({}_{2}\)-(29.35, C4), -CH\({}_{2}\)-(29.48, C7 and C12), -CH\({}_{2}\)-(31.61, C8 and C11), -CH\({}_{2}\)-(33.0, C3), -CH=CH- (129.67, C9 and C10). The NMR show a unique signal pattern, corresponding to a chemically pure compound.  
Figure 2: FT-IR spectra of (**a**) OA; (**b**) 2-aminoethanethiol; and (**c**) OAS.