Probing Polar-π Interactions Between Tetrazoles and Aromatic Rings

Area of Science:

• Organic Chemistry
• Medicinal Chemistry
• Computational Chemistry

Background:

• Tetrazoles are vital heterocyclic compounds in medicinal chemistry, often replacing carboxylic acids.
• Understanding tetrazole noncovalent interactions with aromatic rings is key to their application.
• This study focuses on 2-arylphenyl-1H-tetrazoles to explore these interactions.

Purpose of the Study:

• To investigate the noncovalent interactions between tetrazole and aromatic rings.
• To correlate these interactions with the acidity (pK_a) and proton affinities of tetrazoles.
• To provide insights for the rational design of tetrazole-based pharmaceuticals and materials.

Main Methods:

• Synthesis and characterization of 2-arylphenyl-1H-tetrazoles.
• Spectroscopic and structural analyses.
• Quantum chemical calculations, including molecular orbital and energy decomposition analyses.

Main Results:

• pK_a values and proton affinities correlate with Hammett sigma values of aromatic ring substituents.
• Through-space NH-π and π-π interactions significantly contribute to acidity trends.
• Electrostatic interactions between tetrazole/tetrazolide and aromatic rings are identified as the primary drivers of acidity.

Conclusions:

• Noncovalent interactions, particularly electrostatic and π-based interactions, govern the acidity of 2-arylphenyl-1H-tetrazoles.
• These findings are crucial for the structure-based design of novel tetrazole-containing drugs and functional materials.
• The study deepens the understanding of tetrazole functional roles in chemical sciences.