Giving substance to the Losanitsch series

Area of Science:

• Organic Chemistry
• Stereochemistry
• Spectroscopy

Background:

• Oligoparaxylene compounds are valuable model systems for studying complex molecular architectures.
• Atropisomerism, a form of chirality arising from hindered rotation around a single bond, is crucial in molecular design.
• Understanding the stereochemical diversity of these systems is essential for predicting their properties.

Purpose of the Study:

• To synthesize a series of oligoparaxylene model compounds with varying numbers of paraxylene units (two to six).
• To analyze the resulting mixtures of atropisomers, which possess one to five axes of chirality.
• To determine if the number of observed atropisomers conforms to known mathematical series.

Main Methods:

• Synthesis of oligoparaxylene model compounds.
• Analysis of atropisomer mixtures using dynamic proton nuclear magnetic resonance ((1)H NMR) spectroscopy.
• Comparison of experimental results with theoretical series.

Main Results:

• Successfully synthesized oligoparaxylene model compounds with two to six paraxylene units.
• Identified and quantified mixtures of atropisomers with one to five axes of chirality.
• The number of atropisomers observed in the synthesized compounds was found to be part of the Losanitsch series.

Conclusions:

• The study successfully synthesized and characterized oligoparaxylene model compounds.
• Dynamic (1)H NMR spectroscopy effectively analyzed the complex atropisomeric mixtures.
• The observed number of atropisomers aligns with the Losanitsch series, validating its applicability to these systems.