Effect of chain length on the surface properties of ω-carboxy alkanethiol self-assembled monolayers

Abstract

Self-assembled monolayers (SAMs) of thioglycolic acid, 3-mercaptopropionic acid, 11-mercaptoundecanoic acid, 16-mercaptohexadecanoic acid and bis(carboxydecyl) disulÐde are formed on gold electrodes, respectively. The surface of the x-terminal acid groups in these monolayers are determined using pK a s electrochemical titration, to be 6.1, 5.3, 7.3, 7.9 and 7.3, respectively. The e †ect of chain length on the surface values of x-carboxy alkanethiol SAMs is described. The SAM has a strong inÑuence on the heterogeneous pK a electron transfer rate constant, of the electroactive probe The values of k s , Fe(CN) 6 3~. k s Fe(CN) 6 3~, determined with cyclic voltammetry at the pH values of the inÑection point of the electrochemical titration curves for the four monolayers with carbon number 2, 3, 11 and 16, are calculated to be 7.4 ] 10~3, 4.6 ] 10~3, 4.4 ] 10~3 and 2.6 ] 10~3 cm s~1, respectively. The e †ect of time of immersion for monolayer formation on the defects present in the SAMs formed is discussed. The SAMs of bis(carboxydecyl) disulÐde and 11-mercaptoundecanoic acid show the same surface and values and thus possess the same surface pK a k s properties.

Voltammetry and Single-Molecule in Situ Scanning Tunneling Microscopy of Laccases and Bilirubin Oxidase in Electrocatalytic Dioxygen Reduction on Au(111) Single-Crystal Electrodes

“…The surface pK a for MPA has been reported to be around 5.2À5.6. 61,62 The carboxylic units are therefore partially deprotonated at the pH of the solution, exposing a negative charge to the solution. The surface pK a of MUA has been reported as 7.…”

Epitaxial piezoelectric MEMS on silicon

“…On the other hand, the resonant peak of the cantilever slightly increases under vacuum. It was argued that cantilever structures are less affected by the air damping compared to membrane structures [38]. In atmospheric pressure, our cantilever exhibited a high Q factor of 169.…”

“…When a high quality perovskite-terminated silicon substrate is obtained, epitaxial growth of other perovskite and related materials is facilitated. Conductive perovskite laysers such as (La,Sr)CoO 3 or SrRuO 3 can be used as a bottom electrode that constitutes also an epitaxial layer for successive growth of the epitaxial PZT thin film [38]. The PZT layers epitaxially grown on the aforementioned structure have shown to have improved piezoelectric properties [23,39].…”

“…Material properties for the silicon [38], the epitaxial PZT [20,39], and the Au [40] layers are listed in …”

“…Additionally, it is also used for the device design optimization, in order to find the optimal parameters. Many previous researches have developed analytical power models describing the effect of the parameters on the generated output power of the piezoelectric energy harvesters [31][32][33][34][35][36][37][38]. In this work, the analytical power model for a piezoelectric bimorph cantilever with a mass placed on the free end developed by Roundy et al is applied [12].…”