Lecture: Self-Assembled Monolayers of thiols, characterization and applications in nanoscience and technology.

G RUANO

Santa Fe

Workshop; VI San Luis School on Surfaces, Interfaces and Catalysis; 2018

INTEC

Low dimensionality physical systems offer the possibility of harnessing the quantum nature of matter for both applications and scientific development. Material systems with characteristic lengths in the range of the nanometers of systems have, for better or worse, different features than the bulk. A good strategy to tune the properties of such systems is to alter the chemical makeup of their surfaces with molecules. In that way it is possible to combine both the advantages of reduced scale and the set of functions allowed by the attached moieties. A set of molecules that are particularly well suited for functionalizing metal surfaces, especially those of coinage metals, is the thiols. These molecules form self-assembled structures by means of their interaction with the substrate as well as among themselves, this SAMs (short for self-assembled monolayers) acts as linkers to other molecules, passivating coatings, sensors, molecular electronics, drug delivery systems, etc. The case of nanoparticles coated with thiols is a very interesting case of study, gold nanoparticles in equilibrium expose crystalline planes; the more stable (111) and the second ones the (001). The amount of exposed surface of each kind is determined by the size of the nanoparticles. These crystalline faces, in extended systems such as a single crystal, bares different chemical reactivity so these differences may grow larger with the reduction in size. In this talk a non-exhaustive ensemble of characterization techniques will be presented. By means of XPS (x-ray photoelectron spectroscopy), CVA (cyclic volt-amperometry), SERS (surface enhanced Raman spectroscopy) and the support of DFT (density functional theory) we have been able to face some interesting challenges in the understanding of the morphology1,2, the stability 3,4 and other topics5 in physics and chemistry these SAMS on crystalline surfaces of gold. References 1.Adlayers of Alkanedithiols on Au(111): Effect of Disulfide Reducing AgentLangmuir 29(5), 1400?1406 (2013). 2.Electrochemical, HR-XPS and SERS study of the self-assembly of biphenyl 4,4′-dithiol on Au(111) from solution phase. Surface Science 630, 101-108 (2014). 3.Thermal and Chemical Stability of n-Hexadecanethiol Monolayers on Au(111) in O2 Environments Electrochimica Acta 215, 313-325 (2016). 4.Thermal Stability of Self-Assembled Monolayers of n-Hexanethiol on Au(111)-(1×1) and Au(001)-(1×1). The Journal of Physical Chemistry C 121(50), 27894-27904 (2017) 5.Comparative Study of the Adsorption of Thiols and Selenols on Au(111) and Au(100) Langmuir 33(48), 13733-13739 (2017)