Paper TF+EM+SS-ThA6
Attachment of Conjugated Diruthenium Alkynyl Compounds by Click Chemistry
Thursday, November 1, 2012, 3:40 pm, Room 10
| Session: |
Applications of Self-Assembled Monolayers and Layer-by-Layer Assemblies |
| Presenter: |
S. Pookpanratana, National Institute of Standards and Technology |
| Authors: |
S. Pookpanratana, National Institute of Standards and Technology
S.P. Cummings, Purdue University
T. Ren, Purdue University
C.A. Richter, National Institute of Standards and Technology
C.A. Hacker, National Institute of Standards and Technology
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| Correspondent: |
Click to Email |
Attaching electrochemically-active molecules to a variety of different surfaces is of particular interest for applications in photovoltaic devices, catalysis, and molecular electronics. The family of diruthenium 2-anilinopyridinate (ap) molecules is redox active [1], which makes it an ideal candidate to incorporate on surfaces for molecular catalysis, photoelectrochemical cells for water splitting, and as an active component in molecular electronic devices. Often times, the attachment of a tailored-molecule requires the additional design challenge to incorporate a specific anchoring group (e.g., thiol). Click chemistry has been demonstrated as an effective method to incorporate bulky and complex molecules to a variety of surfaces [2-6]. This route has introduced numerous possibilities of tailoring molecular surfaces.
Here, we have employed a Cu-catalyzed azide-alkyne cycloaddition (CuAAC) click reaction to attach Ru2(ap)4-(C≡C-C6H4-C≡CH), (henceforth referred to as Ru2-alkynyl) to Au and SiO2 surfaces. First, we form an azide-terminated monolayer on Au and SiO2 by using azidoundecanethiol and azidoundecyl trimethoxysilane, respectively. Next, the Ru2-alkynyl is linked to the azide-containing monolayers via a CuAAC reaction (adapted from Ref. 4). The clicked-on Ru2-alkynyl molecule was physically characterized by X-ray photoelectron spectroscopy (XPS) and infrared (IR) spectroscopy. The formation of the azide monolayer on Au and SiO2 surfaces is confirmed by IR measurements. After the CuAAC click reaction of the Ru2-alkynyl to the azide-treated surfaces, there is a reduction of the azide stretch in the IR which indirectly confirms the progress of the click reaction. The incorporation of Ru2-alkynyl is confirmed by XPS, where we estimate the Ru2-alkynyl covers about 10% of the azide sites.
The formation of molecular electronic junctions (Au/Ru2-alkynyl/Si structures) by flip-chip lamination [7] for electrical and backside IR [8] characterizations is currently ongoing. With these results, we are able to obtain a thorough picture linking electrical properties with physical and chemical structure of the diruthenium molecular junctions.
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