Nano Chemistry - Laursen Group
The central role of chemistry in nanoscience is evident from the past 100 years of development of the chemical toolbox. Chemists today are capable of designing and synthesizing almost any imaginable compound; organic or inorganic.
Whereas chemistry has traditionally focused on basic understanding of relationship between structure and reaction, nanochemistry seeks to define and exploit the laws that govern self-assembly, quantum effects, and other fundamental nano scale phenomena.
In that way chemists can make a strong and very important contribution to the broad interdisciplinary field of Nanoscience because chemists can make new systems and study how properties change when the building blocks are changed in a systematic way.
This preparative approach towards elucidation of fundamental scientific questions has proven tremendously successful in the past.
The overall aim of the nanochemistry research is to extend this approach, combined with new structural, optical and electronic tools, to reveal secrets of nanoscale assemblies. In particular we wish to develop our understanding of fundamental principles of chemical and biological self-organization as well as the intrinsic properties of new nanosystems with intriguing chemical, biological, or physical properties.
If you are interested in doing a project at the NanoChemistry Group you are more than welcome to come over and talk to one of us. All the projects can be tuned to fit your interests, and you are part of that process.
Key areas of interest are: molecular electronics, fluorescence, optical sensors, graphene, and molecular self-assembly.
In the Nano Chemistry Group, our research targets the design, synthesis and properties of novel graphene, metallic, organic and f-block containing materials for: molecular electronics, molecular self-assembly, fluorescent probes, and optical sensors. We published our work in both leading general journals: Nature Chemistry, JACS, Chemical Sciences, Chem. Comm., and more specialized journals: ACS Nano, Langmuir, and Advanced Materials.
Our projects are highly interdisciplinary and involve collaboration with physicists, chemists, engineers, biologist as well as medical researchers locally in the NSC, in industry and at academic institutions across the globe. On the following two pages, you will find some examples of recent and on-going research in our group.
Luminescent molecules play a vital role in medical and biological research due to their ability to sense, track and visualize DNA, proteins and other important biomolecules. The development of new, functional and more sensitive sensor molecules is a key activity in the Nano Chemistry Group.
We have recently made two breakthroughs using our luminescent molecules. We were the first to demonstrate the use of near-infrared emission of lanthanide complexes to visualize objects in a confocal microscope (Chem Comm 2015). And we were the first to demonstrate intensity ratiometric sensing of oxygen, by using a molecular system with internal calibration (Chem Sci 2015).
Detailed experimental and theoretical studies of the fundamental photophysical properties of pH sensitive rhodamine dyes have lead us to suggest a new model explaining the function of these important fluorescent indicators (Chem Eur J 2015).
Self-assembly of cationic pi-systems
When organic dyes are packed closely together, their optical properties are strongly depending on the exact structure. In some cases, such materials may act as antennas guiding light energy from large areas to specific molecules or guests in the system, similarly to what happens in the natural photosynthetic machinery. We design and synthesize new dyes with the ability to self-assemble into well-defined nanostructures (e.g. thin films, micelles or nanotubes) and study the relationship between the nanostructure and energy transport.
Ultra-thin and flexible electrodes for molecular electronics
The ultimate goal of molecular electronic research is to make nanoscale electronic components, where molecules play the role of transistors, memory bits and rectifiers. A major challenge in the field is how to create reliable electronic contact to the molecules. When metal contacts are used, short-circuits or damage to the fragile molecular active layer occur frequently. We have developed a method for fabricating and placing a few-nanometer thick layer of a flexible and highly conducting graphene film on top of a single layer of molecules. The thin graphene film protects the molecules and prevent short-circuits from forming. In this way, a new type of molecular device with the soft graphene electrodes have been developed (Advanced Materials 2012, 24, 1333–1339). We have further demonstrated how the optical transparency of the graphene film allows light to reach the active molecules in the nanodevice. By incorporating a light switchable molecule we were able to modulate the electrical conductance by light (Advanced Materials 2013, 25, 4164–4170.). Using the same nanoelectronic device structure, we have recently made bias switchable junctions of organic polymers (Nature Comm. 2015).
We have been investigated a new anchoring group for molecular electronics, based on a triazatriangulene (TATA) platform system. We demonstrated that despite the presence of a sp3 hybridized carbon atom in the conduction path, the TATA platform displays a contact resistance only slightly larger than commonly used thiols (Langmuir 2014).
In collaboration with researchers from the Technical University of Denmark (DTU) and AU, the Nano Chemistry Group is partner in two large research projects with several industry partners on the use of graphene materials for industrial coatings and printed electronics. The projects have a total budget of DKK 65m(EUR 9m).
Since 2010, we have organized an annual international symposium on research and applications of carbon nanomaterials in collaboration with DTU Nanotech.
Ten selected publications
Dong Shi, Christian Schwall, George Sfintes, Erling Thyrhaug, Peter Hammershøj, Marite Cárdenas, Jens B. Simonsen, and Bo W. Laursen, “Counterions control whether self-assembly leads to formation of stable and well-defined unilamellar nanotubes or nanoribbons and nanorods”, Chemistry – A European Journal, 2014, 20, 6853-6856
Thomas Just Sørensen, Anders Ø. Madsen and Bo W. Laursen, “Synthesis and structure of N-alkyl-1,13-dimethoxy-chromeno[2,3,4-kl]acridinium (DMCA+) – the missing azaoxa-helicenium”, Chemistry – A European Journal, 2014, 20, 6391-6400.
Søren Petersen, Yudong He, Jiang Lang, Filippo Pizzocchero, Nicolas Bovet, Peter Bøggild, Wenping Hu, and Bo W. Laursen, “Stepwise reduction of immobilized monolayer graphene oxides”, Chemistry of Materials, 2013, 25 (24), 4839–4848.
Rui Wang, Shengnan Wang, Xiaowei Wang, Jakob A. S. Meyer, Per Hedegård, Bo W. Laursen, Zhihai Cheng and Xiaohui Qiu, “Charge Transfer and Current Fluctuations in Single Layer Graphene Transistors Modified by Self-Assembled C60 Adlayers”, Small,2013, 9, 2420-2426.
Fredrik Westerlund, Henrik Lemke, Tue Hassenkam, Jens Simonsen, Bo W. Laursen, "Self-Assembly and Near Perfect Macroscopic Alignment of Fluorescent Triangulenium Salt in Spin Cast Thin Films on PTFE", Langmuir, 2013, 29, 6728-6736.
Thomas Just Sørensen, Erling Thyrhaug, Mariusz Szabelski, Rafal Luchowski, Ignacy Gryczynski, Zygmunt Gryczynski, and Bo W. Laursen, “Azadioxatriangulenium: a long fluorescence lifetime fluorophore for large biomolecule binding assay”, Methods Appl. Fluorescence, 2013, 1, 025001 (6pp).
Søren Petersen, Magni Glyvradal, Peter Bøggild, Wenping Hu, Robert Feidenhans´l and Bo W. Laursen, “Graphene Oxide as a Mono Atomic Blocking Layer”, ACS Nano, 2012, 6, 8022–8029.
Peter Hammershøj, Thomas Just Sørensen, Bao-Hang Han, and Bo W. Laursen, “Base Assisted One-Pot Synthesis of N,N’,N’’-triaryltriazatriangulenium Dyes – Enhanced Fluorescence Efficiency by Steric Constraints”, Journal of Organic Chemistry, 2012, 77, 5606-5612.
Tao Li, Jonas Rahlf Hauptmann, Zhongming Wei, Søren Petersen, Nicolas Bovet, Tom Vosch, Jesper Nygård, Wenping Hu, Yunqi Liu, Thomas Bjørnholm, Kasper Nørgaard, and Bo W. Laursen, “Solution-Processed Ultrathin Chemically Derived Graphene Films as Soft Top Contacts for Solid-State Molecular Electronic Junctions”, Advanced Materials, 2012, 24, 1333–1339.
Fredrik Westerlund, Jonas Elm, Jacob Lykkebo, Nils Carlsson, Erling Thyrhaug, Björn Åkerman, Thomas Just Sørensen, Kurt V. Mikkelsen and Bo W. Laursen, “Direct probing of ion pair formation using a symmetric triangulenium dye”, Photochemical and Photobiological Sciences, 2011, 10, 1963-1973.
- Professor Bo W. Laursen
- Associate Professors Kasper Nørgaard and Thomas Just Sørensen
- 4 postdocs, 6 PhD students and 8 undergraduates
Nano Chemistry - Laursen Group
Nano-Science Center, Department of Chemistry, Universitetsparken 5, DK-2100 Copenhagen Ø
Bo W. Laursen
Phone: +45 3532 1881
Cell: +45 4043 3881