Modeling proton transfer in imidazole-like dimers: a density functional theory study

Area of Science:

• Computational Chemistry
• Materials Science

Background:

• Proton exchange membrane fuel cells (PEMFCs) are crucial for clean energy.
• Proton transfer in heterocyclic compounds is key to PEMFC performance.
• Imidazole, triazole, and tetrazole dimers are fundamental components of PEMs.

Purpose of the Study:

• To conduct a detailed theoretical study of proton transfer reactions in imidazole, triazole, and tetrazole dimers.
• To compare the efficacy of various density functional theory (DFT) approaches against post-Hartree-Fock (HF) methods.
• To investigate novel proton transfer mechanisms in tetrazole dimers.

Main Methods:

• Density Functional Theory (DFT) calculations.
• Post-Hartree-Fock (HF) methods for reference data.
• Benchmarking of DFT functionals, including a combined BMK//B3LYP model.

Main Results:

• No single DFT approach perfectly matched post-HF reference data.
• A combined BMK//B3LYP model demonstrated high accuracy for energetic and structural properties.
• Two new, more favorable proton transfer mechanisms were identified in tetrazole dimers.
• A direct correlation was found between proton transfer barriers and localized hydrogen charge.

Conclusions:

• Computational modeling of proton transfer in PEM components is challenging.
• The BMK//B3LYP model offers a reliable approach for studying these systems.
• New insights into proton transfer mechanisms in tetrazoles can advance PEM design.