Mathias Senge

@mathiassenge.bsky.social

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Chair of Organic Chemistry - TCD, Alumnus Hans Fischer Senior Fellow - TU Munich. Organic synthesis, light, structures, porphyrins in all shapes and historical settings

Porphyrin atropisomerism is an outstanding tool for the accessibility of shape specific molecules, yet over twenty years after the unusual rotational barriers of nonplanar porphyrins was observed, a quantitative relationship remains at large. There is a growing need to control this phenomenon in nonplanar porphyrin systems due to the mounting interest in these systems as enzyme-mimics and organocatalysts. Hence, in this work the influence of steric bulk on the stability of nonplanar 5,10,15,20-tetraaryl-2,3,7,8,12,13,17,18-octaethyl-porphyrin atropisomers was explored. The library of atropisomeric porphyrins synthesized herein emphasizes the delicate balance that must be achieved between steric bulk without inducing an undesired amount of macrocycle flexibility to obtain an atropisomer with a predictable rotational barrier. To overcome this challenge, a stabilization strategy was devised by exploiting metal coordination to the peripheral porphyrin functionalities, leading to an atroposelective superstructure formation.
Bicyclo[1.1.1]pentane is a rigid aliphatic hydrocarbon with a three-dimensional (3D), propeller-like shape and a molecular size which makes it a targeted bioisosteric replacement for phenylene and acetylene groups in medicinal chemistry. For the pharmaceutical application of BCP, simple, efficient, and cost-effective synthetic tools are required to enable the exploration of BCP’s potential as a bioisostere across a broad chemical space. The synthesis of BCP mono- and diketones remains a challenging task, limited by both substrate scope and expensive photocatalysts. Here we present a protocol for Friedel-Crafts acylation of (hetero)aromatic hydrocarbons with BCP acyl chlorides; in particular, the first method to access diaromatic BCP 1,3-diketones. Reaction optimization, substrate scope, and reactivity of the products are discussed. 35 mono- and diketones are reported accompanied by 7 examples of post-synthetic modifications. The synthesis of a BCP analogue of fenofibrate is reported.
A direct headspace injection method is presented and optimized for the analysis of volatile organic compounds (VOCs) using dielectric barrier discharge ionization-mass spectrometry (DBDI-MS), incorporating an intermediate vial in which the sample headspace is injected. The setup is built of commonly available, cheap consumable parts and easily enables the incorporation of different gases for generating different ionization atmospheres. The method can be fully automated by using standard GC autosamplers, and its rapid analysis time is suitable for high-throughput applications. We show that this method is suitable for both profiling analysis of complex samples such as biofluids and quantitative measurements for real-time reaction monitoring. Our optimized method demonstrated improved reproducibility and sensitivity, with detection limits for compounds tested in the high nanomolar to the low micromolar range, depending on the compound. Key parameters for method optimization were identified such as sample vial volume, headspace-to-liquid ratio, incubation temperature, and equilibration time. These settings were systematically evaluated to maximize the signal intensity and improve repeatability between measurements. Two use cases are demonstrated: (i) quantitative measurement of ethanol production by a metal–organic framework from CO2 and (ii) profiling of biofluids following the consumption of asparagus.
Bimanes, a class of molecules based on the 1H,7H-pyrazolo[1,2-a]pyrazole-1,7-dione scaffold, were first introduced by E. M. Kosower in 1978. In this study, we report the topochemical cycloaddition of diethyl 2,6-dichloro-1,7-dioxo-1H,7H-pyrazolo[1,2-a]pyrazole-3,5-dicarboxylate (Cl2B), initiated by visible light. Crystal structure analysis confirmed that the reactive double bonds are parallel and coplanar, in line with the Schmidt criteria for topochemical cycloaddition. Additionally, two other bimane derivatives with different substitution patterns were synthesized and investigated. Our findings suggest that functionalizing bimanes to redshift their absorption maxima into the visible-light spectrum provides a promising strategy for synthesizing substituted cyclobutanes without the need for ultraviolet irradiation.
The growing demand for energy and the excessive use of fossil fuels represents one of the main challenges for humanity. Storing solar energy in the form of chemical bonds to generate solar fuels or value-added chemicals without creating additional environmental burdens is a key requirement for a sustainable future. Here we use biomimetic artificial photosynthesis and present a dPCN-224(H) MOF-based photocatalytic system, which uses reactive oxygen species (ROS) to activate and convert CO2 to ethanol under atmospheric conditions, at room temperature and in 2-5 h reaction time. The system provides a CO2-to-ethanol conversion efficiency (CTE) of 92%. Furthermore, this method also allows the conversion of CO2 through direct air capture (DAC), making it a rapid and versatile method for both dissolved and gaseous CO2.
#Crystal structure of an intercalated #porphyrin dimer which is stable in solution.