Self-assembly of catecholic ferrocene and electrochemical behavior of its monolayer

Abstract

Self-assembly of catecholic ferrocene was studied on different surfaces. The self-assembly kinetics of Fcterminated (Fc-dopamine) self-assembled monolayers (SAMs) and their stability have been studied and characterized using atomic force microscopy (AFM) and cyclic voltammetry (CV), respectively. AFM images have revealed that the self-assembly process of Fc-dopamine molecules on a mica surface follows the systematic increase of surface coverage with assembly time until a closely packed density is reached. The redox behavior of the Fc-dopamine monolayer in NaClO 4 electrolyte solutions was characterized using CV, and the stability of the Fc-dopamine SAMs on an Au surface at different pH values and voltages was evaluated. CV results show that the Fc-dopamine SAMs are stable over a scan voltage range of À0.8-1.0 V under pH values lower than 11, but very rapidly destroyed above pH 11. Finally, the wetting behavior of the Fc-dopamine grafted on rough surfaces is tuned by a redox reaction of the Fc group in SAMs, which exhibits superhydrophobicity with a static water contact angle of 161 on anodized alumina surfaces, and hydrophilicity with a CA of 5 after Fc is oxidized. The work provides useful information for understanding the adhesion and deposition mechanisms of catecholic compounds on substrates.Scheme 1 The synthetic pathway to the Fc-dopamine compound.This journal is

Single molecule vs. large area design of molecular electronic devices incorporating an efficient 2-aminepyridine double anchoring group

“…These studies include monodentate molecules using anchor groups such as thiols [14][15][16][17] amines, 14,18,19 methyl sulfides, 20 selenols, 21,22 cyano, 23,24 isocyanides, 25 nitriles, 26 hydroxyl, 27 ethynylbenzenes, 28 isothiocyanates, 29 pyridines, [30][31][32][33][34] N-heterocyclic carbenes, 35 dimethylphosphine, 36 dihydrobenzo[b]thiophenes, 37 4-(methylthio)phenyl groups, 38 thienyl rings, 39 diphenylphosphines, 40 trimethylsilylethynyl, [41][42][43] tetrathiofulvalenes, 44 triazatriangulenes, 45 and fullerenes. [46][47][48] More recently, bidentate molecules such as carboxylic acids, 47,49,50 carbodithioates, 51,52 dithiocarbamates, 53,54 norbornyldithiol, 55 cathecols, 56 or pyrazole 57 and also multipodal platforms…”

Unconventional Single-Molecule Conductance Behavior for a New Heterocyclic Anchoring Group: Pyrazolyl

“…From the molecular electronics point of view, a strong and defined electronic coupling between the electrode, the anchor groups, and the rest of the molecule is required in order to promote a high transmission of the overall junction. ,, However, in some cases, the steric requirements imposed by the design of molecules with two or more anchoring atoms or groups results in the disruption of π-conjugation in the molecular structure, which compromises electrical transmission of the junction. However, interest in the topic is growing fast, and examples of multidentate platforms with potential uses in molecular electronics have already been published. ,,− In this context, the exploration of multidentate materials has focused mainly on bidentate platforms such as dithiols, − diols (cathecol), carbodithioates, ,, dithiocarbamates, − and norbornyldithiol. , A few examples of tridentate − and tetradentate molecular platforms have also been reported.…”

Bioinspired polymeric pigments to mimic natural hair coloring

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