Defining a Chemical Space of π-Conjugated Hydrocarbons by Unit-Based Construction

Area of Science:

• Materials Science
• Organic Chemistry
• Computational Chemistry

Background:

• π-Conjugated hydrocarbons are essential building blocks in materials science.
• Current methods for designing and discovering these molecules lack systematic frameworks, limiting exploration of their chemical space.
• Ensuring structural validity during generation is a key challenge.

Purpose of the Study:

• To introduce CARBOT, a unit-based molecule generation framework specifically designed for π-conjugated hydrocarbons.
• To provide a systematic and computationally efficient approach for exploring the chemical space of these molecules.
• To facilitate the design and discovery of novel functional π-conjugated materials.

Main Methods:

• Development of CARBOT, a framework utilizing a minimal set of chemically rational unit transformations (vinyl- and ethynyl-group addition, cyclization).
• Inclusion of composite transformations to accelerate access to aromatic frameworks.
• Application of depth-first search and substructure-matching scores for molecule generation and validation.
• Demonstration of scalability to large molecules (up to C200H100).

Main Results:

• CARBOT is proven sound and complete for neutral Kekulé hydrocarbons (sp and sp² hybridized carbons).
• The framework successfully rediscovers diverse π-conjugated hydrocarbons, including nonplanar nanographenes, carbon nanobelts, and Möbius hydrocarbons.
• The generation process is efficient and scalable, handling large molecular structures.

Conclusions:

• CARBOT offers a systematic foundation for the design and discovery of π-conjugated hydrocarbons.
• The framework addresses limitations in exploring chemical space while ensuring structural validity.
• CARBOT is expected to accelerate the development of new functional carbon-based materials.