Non-conventional Hydrogen Bonding and Aromaticity: A Systematic Study on Model Nucleobases and Their Solvated...

Area of Science:

• Computational Chemistry
• Supramolecular Chemistry
• Organic Chemistry

Background:

• Aromaticity is key to understanding heterocycle structure and behavior.
• Sulfur/selenium-centered hydrogen bonds (S/SeCHBs) are explored in relation to aromaticity.
• Models of nucleobases, including 2-Pyridone (2PY) and its sulfur (2TPY) and selenium (2SePY) analogs, are used.

Purpose of the Study:

• To investigate the interconnection between aromaticity and S/SeCHBs in heterocyclic systems.
• To analyze the impact of replacing oxygen with sulfur or selenium on aromaticity.
• To explore how S/SeCHBs influence aromaticity in dimers, heterdimers, and hydrated clusters.

Main Methods:

• Computational chemistry methods were employed.
• Nucleus-independent chemical shift (NICS) was calculated.
• Gauge induced magnetic current density (GIMIC) was utilized.

Main Results:

• Replacing oxygen with sulfur or selenium in heterocycles initially reduced aromaticity.
• Significant aromaticity enhancement was observed in 2TPY and 2SePY dimers linked by S/SeCHBs (57% and 80% increase, respectively).
• Aromaticity enhancement was also found in 1:1 hydrogen-bonded complexes, micro hydrated clusters, and bulk hydration.

Conclusions:

• S/SeCHBs can significantly enhance aromaticity in heterocyclic systems.
• Incorporating sulfur and selenium into heterocycles offers a route to design novel supramolecular building blocks.
• This work provides insights into the interplay between hydrogen bonding and aromaticity in sulfur and selenium-containing heterocycles.