Noncovalent Mg···N Interactions as Tunable Electronic Perturbations in Pyridine-Based Single-Molecule Junctions

Area of Science:

• * Molecular interactions and supramolecular chemistry.
• * Quantum chemistry and condensed matter physics.
• * Nanoscale electronics and molecular devices.

Background:

• * Noncovalent interactions are crucial for molecular assembly and function.
• * Understanding electron transport in single-molecule junctions is key for molecular electronics.
• * Pyridine derivatives offer tunable electronic properties for molecular devices.

Purpose of the Study:

• * To investigate magnesium-to-nitrogen (Mg···N) noncovalent interactions in substituted pyridine-MgH2 complexes.
• * To explore the impact of these interactions on single-molecule electron transport.
• * To establish a molecular framework for single-electron transistor-like behavior.

Main Methods:

• * Comprehensive theoretical investigation using geometry optimization, binding-energy analysis, AIM, NBO, and SAPT calculations.
• * Density Functional Theory-Non-Equilibrium Green's Function (DFT-NEGF) simulations of molecular junctions.
• * Analysis of quantum interference and Coulomb staircase phenomena in I-V responses.

Main Results:

• * Mg···N interactions are electrostatically dominated, with strengths modulated by pyridine substituents.
• * Complex formation reduces the HOMO-LUMO energy gap by 1-2.5 eV.
• * Mg···N bonding significantly alters transmission characteristics, leading to quantized charge transport and Coulomb staircase behavior.

Conclusions:

• * Mg···N noncovalent interactions act as tunable electronic perturbations in molecular junctions.
• * These interactions can effectively modulate conductance in pyridine-based single-molecule systems.
• * The studied complexes provide a feasible molecular framework for exploring single-electron transistor-like behavior.