On the Intermolecular Interactions in Thiophene-Cored Single-Stacking Junctions.

Area of Science:

• Physical Chemistry
• Materials Science
• Quantum Chemistry

Background:

• Understanding electronic conductance in single-molecule junctions is crucial for molecular electronics.
• Density-functional theory (DFT) and experimental methods have been used to study pi-conjugated stacking junctions.

Purpose of the Study:

• To provide a reliable description of stacked configurations in thiophene-cored systems.
• To quantify intermolecular binding strength and investigate its physical origin.

Main Methods:

• Dispersion-corrected DFT for finding minimal structures.
• Coupled cluster method with singles, doubles, and perturbative triples [CCSD(T)] and complete basis set (CBS) extrapolation for interaction energies.
• DFT-based symmetry-adapted perturbation theory (SAPT) for investigating the physical origin of interactions.

Main Results:

• CCSD(T)/CBS interaction energies for S-Tn dimers increase linearly with the number of thiophene units (n ≤ 6).
• Significant conformational differences in flanking 2-thiophene groups of S-T1 and S-T2 were identified.
• SAPT/CBS computations elucidated the physical origins of intermolecular interactions.

Conclusions:

• High-level quantum chemical calculations offer reliable insights into the electronic properties of supramolecular junctions.
• The number of thiophene units and conformation significantly influence intermolecular binding and electronic conductance.
• These findings contribute to the design of materials for molecular electronics.