Inhaltspezifische Aktionen

Project D - Controlling Reactions and Precursor Design

Coordinating PIs

Project PIs

  • Prof. Dr. André Schirmeisen

 

Background

In this subproject, methods of selective reaction control are to be developed in which precursor design and surface interaction interact synergistically. Synthetic-preparative chemistry strives for high selectivities in product formation under economic and ecological aspects. This applies increasingly to on-surface synthesis (OSS), since separation of by-products is at least more difficult here. Selective reaction control and atom economy are therefore particularly important here on the one hand, but on the other hand more difficult than in solution, since possibilities of selectivity control from solution chemistry are omitted. In this project, therefore, OSS-specific principles for selectivity control will be developed. In the limited parameter space of OSS, the following are available for this purpose: the structural design of the molecular precursors (precursor design), the interaction with the surface, coverage and temperature.

 

Scientific Goals

First, suitable structural principles to control the competitive formation of cyclic and linear products in one-dimensional (1D) oligo and polymerization, respectively, will be established. Molecular precursors for the Ullmann coupling (and related reactions) will be optimized on the basis of STM, XPS, NIXSW and NEXAFS measurements (as well as AFM - subproject A and theory - subproject F) so that a specific product occurs preferentially. Based on this, competitive reactions with periodic or fractal product formation will be investigated in the field of 2D polymerization. The second objective is the optimization of substrate influence on selectivity and is closely related to objective 1, using not only pure metal surfaces but also alloys and nanotemplated structures. The third objective is to optimize on-surface dehydrogenation and cyclodehydrogenation reactions as a function of the structure of the carbon skeleton (subproject E). The control of selectivity via the degree of coverage (dilution principle) and temperature represent the fourth project goal.