Synthesis and Characterization of a Thiol-Tethered Tripyridyl Porphyrin on Au(111)

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• 作者：Yang-Hsiang Chan ; Amanda E. Schuckman ; Lisa M. P&eacute ; rez ; Mikki Vinodu ; Charles M. Drain ; James D. Batteas
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：April 17, 2008
• 年：2008
• 卷：112
• 期：15
• 页码：6110 - 6118
• 全文大小：741K
• 年卷期：v.112,no.15(April 17, 2008)
• ISSN：1932-7455

文摘

Porphyrins are actively studied for use in molecular and organic electronic components of devices becauseof their diverse tunable optical and electronic properties. In this study, mixed self-assembled monolayers(SAMs) of dodecanethiol and a tripyridyl porphyrin attached to a thiol tether via a perfluorinated phenyl ring(TPy₃PF₄-SC₅SH) were prepared on Au(111) substrates. The synthetic strategy allows for rapid formationof derivatives with different tethers. The surface structural and electronic properties of mixed monolayerSAMs of the porphyrin inserted into the dodecanethiol matrix were investigated using scanning tunnelingmicroscopy (STM), atomic force microscopy (AFM), Fourier transform infrared reflection-absorptionspectroscopy (FT-IRAS), and X-ray photoelectron spectroscopy (XPS). Density functional theory (DFT)calculations were also employed to evaluate the analytical vibrational frequencies of the TPy₃PF₄-SC₅SHmolecule as well as its electronic structure. For the mixed monolayers, the morphology of the porphyrinmolecules was probed by STM where it was found that the molecules assembled into domains of ~2 and 6nm. AFM shows that the molecules protrude above the n-dodecanethiol layer by ~0.9 nm, while by STM,apparent heights of only ~0.5 nm were observed, suggesting limited tunneling efficiency. Stochastic switchingof the porphyrin molecules was also observed during STM measurements in the mixed monolayer and islikely associated with conformational changes within the monolayer since these molecules tended to insertnear defects within the SAM.