# Autodesmotic reactions for general strain energy evaluation in polycyclic aromatic nanocarbons

## TL;DR

This paper introduces a new method called autodesmotic reactions to accurately evaluate strain energy in complex carbon nanomaterials using a single quantum calculation.

## Contribution

The novel autodesmotic reaction framework enables efficient and accurate strain energy evaluation in polycyclic aromatic nanocarbons.

## Key findings

- Autodesmotic reactions preserve molecular topology and ensure proper π-energy balance.
- The method is accurate and robust, validated across diverse carbon nanobelts and other structures.
- It reveals strain–structure–property relationships and requires only one quantum chemical calculation per molecule.

## Abstract

Strain energy fundamentally shapes the structure, stability, and reactivity of π-conjugated nanocarbons, making its accurate quantification essential for rational molecular design. However, existing approaches rely on arbitrary reference choices, overlook critical π-energy balance, or demand extensive computations, limiting their reliability and scope. Here we introduce autodesmotic reactions, a general and efficient framework that maps any strained π-conjugated nanocarbon onto an operationally defined single-molecule reference while preserving molecular topology and ensuring proper π-energy balance. This reference resides within a virtual chemical space constructed from physically motivated models trained on planar benzenoid hydrocarbons. Benchmarking across diverse carbon nanobelts confirms the accuracy and robustness of the method, and applications to circulenes, helicenes, bowl-shaped hydrocarbons, nanotubes, and fullerenes demonstrate its broad versatility and reveal insightful strain–structure–property relationships. By resolving the fundamental and computational limitations of established methods, autodesmotic reactions provide a rigorous, general, and highly efficient route to strain energy evaluation, requiring only a single quantum chemical calculation per molecule. As a conceptual advance linking topology, π-energy, and strain, this framework lays a foundation for accelerated design of strained aromatic nanocarbons and offers a platform readily extensible via emerging machine-learning strategies.

Understanding strain energy is crucial for the design of π-conjugated nanocarbons, yet current quantification methods are limited. Here, the author introduces autodesmotic reactions as a framework that accurately evaluates strain energy using only a single quantum chemical calculation per molecule, demonstrating application to nanobelts, circulenes, helicenes, bowl-shaped hydrocarbons, nanotubes, and fullerenes.