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Synthesis of thioacetate-functionalized cobalt(II) porphyrins and their immobilization on gold surface - Characterization by X-ray photoelectron spectroscopy
Stockholm University, Sweden.
Stockholm University, Sweden.
Stockholm University, Sweden.
Stockholm University, Sweden.
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2006 (English)In: European Journal of Organic Chemistry, ISSN 1434-193X, no 5, p. 1193-1199Article in journal (Refereed) Published
Abstract [en]

Cobalt tetraarylporphyrins 1-Co and 2-Co with thioacetate-functionalized carbon chains on the aryl groups were synthesized. The cobalt porphyrin 2-Co was immobilized on a gold surface after deprotection of the S-acetyl group. The immobilized porphyrin was studied by X-ray Photoelectron Spectroscopy (XPS) and the results suggest that a complete monolayer of porphyrins is formed.

Place, publisher, year, edition, pages
2006. no 5, p. 1193-1199
National Category
Physical Chemistry
Identifiers
URN: urn:nbn:se:mdh:diva-4162DOI: 10.1002/ejoc.200500656ISI: 000235821600014Scopus ID: 2-s2.0-33644761874OAI: oai:DiVA.org:mdh-4162DiVA, id: diva2:121036
Available from: 2008-02-06 Created: 2008-02-06 Last updated: 2015-07-08Bibliographically approved
In thesis
1. Heterogenization of a Cobalt Porphyrin Catalyst Investigated by Scanning Probe Microscopy and X-Ray Photoelectron Spectroscopy: The Effect on Catalysis of Oxidation Reactions
Open this publication in new window or tab >>Heterogenization of a Cobalt Porphyrin Catalyst Investigated by Scanning Probe Microscopy and X-Ray Photoelectron Spectroscopy: The Effect on Catalysis of Oxidation Reactions
2008 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Construction of advanced materials through self-assembly on the molecular level is an important route to achieve novel functionality. Self-assembly of thiols onto gold has during the last decades shown greate promise in the creation of functional nanomaterials, such as sensors or catalysts, but for many applications silicon should be a better substrate since it offers semiconducting properties and better processing abilities in addition to being cheaper. This work describes an efficient novel method to incorporate reactive disulfide bonds onto a silica surface under mild reaction conditions. The reactive thiol groups introduced onto the silica surface will be oxidized but is then converted into highly reactive thiopyridyl groups, which can easily be utilized for further organic synthesis involving thiol-containing molecules.

Cobalt tetraarylporphyrins with thioacetate-functionalized carbon chains on the aryl groups were synthesized (CoTPP-L) and were used as a model system for investigating catalytic activity in homogeneous and heterogeneous oxidation catalysis. For heterogeneous catalysis CoTPP-L was immobilized onto gold surfaces through thiol-gold self-assembly, and onto silica surfaces by the above mentioned disulfide exchange method.

The properties of the molecular layers were characterized on the molecular level by means of X-ray photoelectron spectroscopy (XPS) and scanning probe microscopy (SPM). The immobilization on gold surfaces took place through the formation of multiple thiolate bonds and it could be controlled by varying the preparation scheme. More thiolate bonds form if the thioacetyl protective groups of the thiol linkers are cleaved off prior to immobilization. The CoTPP-L molecules were in all cases found to form stable disordered monolayers on gold surfaces. On silica surfaces the CoTPP-L forms patchwise multilayers.

The catalytic performance of the heterogenized systems (CoTPP-L immobilized onto gold or silicon wafers) was evaluated and it was found that the strong inactivation observed for their homogeneous congener was avoided. As a result, the turnover number per molecule in heterogeneous catalysis was at least 100 times higher than that of the corresponding homogeneous catalyst. It is thus demonstrated that the performance of these catalysts can be dramatically improved if the catalyst arrangement can be controlled on the molecular level. Work is ongoing to extend the system to high surface area materials.

Place, publisher, year, edition, pages
Akademin för hållbar samhälls- och teknikutveckling, 2008
Series
Mälardalen University Press Dissertations, ISSN 1651-4238 ; 57
National Category
Other Chemical Engineering
Research subject
Bioteknik/kemiteknik
Identifiers
urn:nbn:se:mdh:diva-492 (URN)978-91-85485-71-0 (ISBN)
Public defence
2008-03-07, Filen, Verktyget, Smedjegatan 37, Eskilstuna, 10:00
Opponent
Supervisors
Available from: 2008-02-06 Created: 2008-02-06

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