cfaed Seminar Series

Prof. Markus Lackinger , Deutsches Museum & Technische Universität München

On-Surface Synthesis of 2D polymers – the role of bond reversibility

02.02.2017 (Thursday) , 13:00 - 14:00
Seminar Room 115 (HAL) , Hallwachsstr. 3 , 01067 Dresden

The polymerization of organic monomers on solid surfaces is a promising and versatile
synthetic route for the bottom-up fabrication of 2D polymers. Various coupling reactions
are successfully employed for the on-surface synthesis of extended covalent
nanostructures that are inaccessible by other synthetic means. Yet, many important
reactions, as for instance Ullmann coupling, normally proceed irreversibly. Consequently,
the lack of error correction mechanisms during growth inevitably results in networks with
high defect densities.
In contrast, supramolecular self-assembly based on reversible intermolecular interactions
is well-known to yield networks with high structural quality. The presentation introduces
and discusses different concepts, how bond reversibility and non-covalent self-assembly
can also be utilized for the on-surface synthesis of covalent nanostructures: A more
obvious option is the use of coupling reactions that can proceed reversibly as for instance
boronic acid condensation. Yet, on the appropriate surface even a notoriously irreversible
reaction as Ullmann coupling can exhibit an organometallic intermediate featuring bond
reversibility. We will demonstrate that equilibration of these organometallic intermediates is
advantageous to improve the structural quality of covalent networks. Lastly, the most
elegant, but most specialized option is to firstly use non-covalent interactions for preassembling
an ordered structure, and to secondly induce covalent cross-linking while
maintaining this initial arrangement. A topochemical photopolymerization on a solid
surface will be discussed as an implementation of this principle.

Markus Lackinger studied physical engineering at the University of Applied
Sciences in Munich from 1994 to 2000. In his postgraduate studies he
specialized in the field of surface science and nano science. In 2003 he
obtained a PhD from the University of Technology in Chemnitz in experimental
physics. During the PhD thesis he had a research stay at Columbia University
with George W. Flynn. After his graduation he gained additional experience
through postdoctoral fellowships at the Ludwig-Maximilians-University (LMU)
with Prof. Wolfgang Heckl (03-05) and at the University of California at Irvine
(UCI) with Prof. Wilson Ho (05-06). Since 2006 Markus Lackinger leads a
research group focused on molecular nano-science on surfaces, initially at the
LMU, currently at the Deutsches Museum in cooperation with the Technical
University Munich.

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