Topological Ring Currents in Open-Shell Homologues of Clar's Goblet and Triangulene
Timothy K Dickens1, Roger B Mallion1
1Peterhouse, Cambridge CB2 1RD, England, United Kingdom.
The Journal of Physical Chemistry. A
|December 8, 2025
Summary
The Hückel-London-Pople-McWeeny (HLPM) formalism now calculates ring currents in open-shell systems. This study analyzes trends in diradicals and polyradicals, comparing HLPM results with advanced computational methods.
Area of Science:
- Quantum Chemistry
- Theoretical Chemistry
- Organic Electronics
Background:
- The Hückel-London-Pople-McWeeny (HLPM) formalism is a method for calculating topological ring currents.
- Previous limitations excluded open-shell π-electron-conjugated systems from HLPM analysis.
- Recent advancements enabled the extension of HLPM to these systems.
Purpose of the Study:
- To investigate quantitative trends in topological ring currents for various diradicals and polyradicals.
- To apply the extended HLPM formalism to Clar's goblet, its homologues, and triangulene derivatives.
- To compare HLPM-derived ring current patterns with those from advanced computational methods.
Main Methods:
- Extension of the Hückel-London-Pople-McWeeny (HLPM) formalism to open-shell systems using Configurational State Averaging (CSA).
- Calculation of topological ring currents for Clar's goblet, its homologues, and triangulene derivatives.
- Comparison of HLPM results with pictorial current maps from pseudo-π and ab initio calculations.
Main Results:
- The extended HLPM formalism successfully calculates topological ring currents in open-shell conjugated systems.
- Quantitative trends in ring currents were identified for various diradicals and polyradicals.
- HLPM results show good agreement with advanced computational methods, validating the approach.
Conclusions:
- The modified HLPM formalism provides a valuable tool for studying electronic properties of open-shell conjugated systems.
- This approach allows for detailed analysis of topological ring currents in complex radical structures.
- The findings contribute to a deeper understanding of electronic delocalization in conjugated organic molecules.
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