Modification of electrode surfaces by self-assembled monolayers of thiol-terminated oligo(phenyleneethynylene)s.

Content Provider	Semantic Scholar
Author	Kaur, Inderpreet Zhao, Xiaotao Bryce, Martin R. Schauer, P. A. Low, Paul J. Kataky, Ritu
Copyright Year	2013
Abstract	The wire-like properties of four S-(4-{2-[4-(2-phenylethynyl)phenyl]ethynyl}phenyl) thioacetate derivatives, PhC≡CC(6)H(4)C≡CC(6)H(4)SAc (1), H(2)NC(6)H(4)C≡CC(6)H(4)C≡CC(6)H(4)SAc (2), PhC≡CC(6)H(2)(OMe)(2)C≡CC(6)H(4)SAc (3) and AcSC(6)H(4)C≡CC(6)H(4)C≡CC(6)H(4)SAc (4) (Figure 1), all of which possess a high degree of conjugation along the oligo(phenyleneethynylene) (OPE) backbone, were investigated as self-assembled monolayers (SAMs) on gold and platinum electrodes by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The redox probe [Fe(CN)(6)](4)(-) was used in both the CV and impedance experiments. The results indicate that the thiolates derived from thioacetate-protected precursor molecules 1 and 2 form well-ordered monolayers on a gold electrode, whereas SAMs derived from 3 and 4 exhibit randomly distributed pinholes. The electron tunnelling resistance and fractional coverage of SAMs of all four compounds were examined using electron tunnelling theory. The analysis of the results reveal that the well-ordered SAMs of 1 and 2 exhibit higher charge-transfer resistance in comparison to the defect-ridden SAMs of 3 and 4. The additional steric bulk offered by the methoxy groups in 3 is likely to prevent efficient packing within the SAM, leading to a microelectrode behaviour, when assembled on a gold electrode surface. The protected dithiol derivative 4 probably binds to the surface through both terminal groups which prevents dense packing and leads to the formation of a monolayer with randomly distributed pinholes. Atomic force microscopy (AFM) was used to examine the morphology of the monolayers, and height images gave root-mean-square (RMS) roughness's which are in agreement with the proposed SAM structures.
File Format	PDF HTM / HTML
DOI	10.1002/cphc.201200744
PubMed reference number	23316022
Journal	Medline
Volume Number	14
Issue Number	2
Alternate Webpage(s)	http://dro.dur.ac.uk/15710/1/15710.pdf?DDD7+dch0pjl+dul4eg=
Alternate Webpage(s)	https://doi.org/10.1002/cphc.201200744
Journal	Chemphyschem : a European journal of chemical physics and physical chemistry
Language	English
Access Restriction	Open
Content Type	Text
Resource Type	Article