Kekulé Institute of Organic Chemistry and Biochemistry

Current note

As of WS 2022/23, the courses will once again be held in person. However, hybrid or online events are also possible.

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© U. Weynand

Research topics

Biochemistry and natural products
Catalysis and sustainable chemistry
New methods in synthesis
Organo-electrochemistry
Organometallic compounds in synthesis
Organic materials
Polymer chemistry
Supramolecular chemistry and sensors

OC-News
Modular Bicyclophane-Based Molecular Platforms

Bicyclophane-based molecular platforms form extended 2D crystalline monolayers after adsorption from solution onto HOPG and contain orthogonal pillars that point towards the supernatant solution phase.

Nanoscale π-conjugated ladders

It is challenging to increase the rigidity of a macromolecule while maintaining solubility. Established strategies rely on templating by dendrons, or by encapsulation in macrocycles, and exploit supramolecular arrangements with limited robustness. Covalently bonded structures have entailed intramolecular coupling of units to resemble the structure of an alternating tread ladder with rungs composed of a covalent bond. We introduce a versatile concept of rigidification in which two rigid-rod polymer chains are repeatedly covalently associated along their contour by stiff molecular connectors. This approach yields almost perfect ladder structures with two well-defined π-conjugated rails and discretely spaced nanoscale rungs, easily visualized by scanning tunnelling microscopy. The enhancement of molecular rigidity is confirmed by the fluorescence depolarization dynamics and complemented by molecular-dynamics simulations. The covalent templating of the rods leads to self-rigidification that gives rise to intramolecular electronic coupling, enhancing excitonic coherence. The molecules are characterized by unprecedented excitonic mobility, giving rise to excitonic interactions on length scales exceeding 100 nm. Such interactions lead to deterministic single-photon emission from these giant rigid macromolecules, with potential implications for energy conversion in optoelectronic devices.

Subcomponent self-assembly of circular helical Dy6(L)6 and bipyramid Dy12(L)8 architectures

Subcomponent self-assembly gave access to Dy12(L)8 and Dy6(L)6 architectures via second-order template effects. The Dy6(L)6 assembly behaves as a single-molecule magnet exhibiting a high anisotropy barrier and butterfly-shaped magnetic hysteresis.

Structural Disorder as the Origin of Optical Properties and Spectral Dynamics in Squaraine Nano-Aggregates

In contrast to regular J- and H-aggregates, thin film squaraine aggregates usually have broad absorption spectra containing both J-and H-like features, which are favorable for organic photovoltaics. Despite being successfully applied in organic photovoltaics for years, a clear interpretation of these optical properties by relating them to specific excited states and an underlying aggregate structure has not been made. In this work, by static and transient absorption spectroscopy on aggregated n-butyl anilino squaraines, we provide evidence that both the red- and blue-shifted peaks can be explained by assuming an ensemble of aggregates with intermolecular dipole–dipole resonance interactions and structural disorder deriving from the four different nearest neighbor alignments - in sharp contrast to previous association of the peaks with intermolecular charge-transfer interactions. In our model, the next-nearest neighbor dipole-dipole interactions may be negative or positive, which leads to the occurrence of J- and H-like features in the absorption spectrum. Upon femtosecond pulse excitation of the aggregated sample, a transient absorption spectrum deviating from the absorbance spectrum emerges. The deviation finds its origin in the excitation of two-exciton states by the probe pulse. The lifetime of the exciton is confirmed by the band integral dynamics, featuring a single-exponential decay with a lifetime of 205 ps. Our results disclose the aggregated structure and the origin of red- and blue-shifted peaks and explain the absence of photoluminescence in squaraine thin films. Our findings underline the important role of structural disorder of molecular aggregates for photovoltaic applications.

 

Events
GDCh-Kolloquium Prof. Dr. Carole Duboc
Chemische Institute - ...
05:00 PM - 06:00 PM
Bio-inspired catalysts for clean H<sub>2</sub> production Hydrogen production through water splitting emerges as a pertinent solution in the long run for ...
KOPO 2024
Physikzentrum Bad Honnef
03:30 PM
KOPO 2024 CONJUGATED OLIGOMERS AND POLYMERS 12th Workshop May 26-29, 2024 Physikzentrum Bad Honnef More information coming soon

Working groups

                                                                                              

Jun. Prof. Dr. Bunescu
© A. Bunescu

Jun. Prof. Ala Bunescu

Transition Metal Catalysis
Organic Synthesis

Dickschat
© J. Dickschat

Prof. Dr. Jeroen Dickschat

Natural products chemistry
Biosynthesis, synthesis, structure elucidation

Engeser
© M. Engeser

PD Dr. Marianne Engeser

Mass spectrometry
Mechanism elucidation

AndreasGansäuerNeu
© Sophia Gansäuer

Prof. Dr. Andreas Gansäuer

Catalysis
Radical chemistry
Stereoselective synthesis

höger
© G. Hübl

Prof. Dr. Sigurd Höger

Organic chemistry
of complex systems

Lützen
© A. Lützen

Prof. Dr. Arne Lützen

Supramolecular chemistry
Organic synthesis
NMR spectroscopy

menche
© D. Menche

Prof. Dr. Dirk Menche                        

Natural products:
Characterization, total synthesis,
synthesis methods

Jester.png
© Jester

Dr. Stefan-Sven Jester

Junior Research Group
Supramolecular patterning of surfaces,
Scanning probe methods

von Krbek
© L. von Krbek

Dr. Larissa von Krbek

Junior Research Group
Fuel-driven supramolecular systems:
Synthesis, development and investigation

Chemistry minor

Courses for students of human medicine, dentistry and nutrition and food sciences

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© U. Weynand

Chemistry for physicians and dentists

Seminar, lecture and practical course

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© U. Weynand

Chemistry for nutrition and food scientists

Seminar, lecture and practical course

Departmental library

The Chemistry Department Library is a joint library of the Chemistry Department located in the building of the Kekulé Institute of Organic Chemistry and Biochemistry (EG). It consists of a collection of monographs, journals and series and is run as a reference library. A public photocopier is available in the library.

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