Substituted adenine quartets: interplay between substituent effect, hydrogen bonding, and aromaticity.

Area of Science:

• Computational chemistry
• Molecular biology
• Supramolecular chemistry

Background:

• Adenine is a fundamental component of DNA and RNA.
• Adenine can form self-organizing structures called adenine quartets (A4) via hydrogen bonds.
• These structures are analogous to guanine quartets.

Purpose of the Study:

• To computationally investigate the impact of various substituents on 9H-adenine and its quartets.
• To analyze the electronic structure, hydrogen bond strength, and aromaticity of substituted adenine quartets.
• To understand how substituent properties and positions affect quartet stability and adenine's electronic characteristics.

Main Methods:

• Density Functional Theory (DFT) calculations were employed.
• The study examined adenine with substituents X = NO2, Cl, F, H, Me, and NH2.
• Analysis focused on A4-N1, A4-N3, and A4-N7 quartet types.

Main Results:

• Substituents significantly alter the electronic structure of adenine and its quartets.
• The electronic nature and position of substituents modulate hydrogen bond strength and quartet stability.
• Tetramer formation can induce changes in substituent electronic properties and adenine ring aromaticity.
• The effect of a substituent can be context-dependent, strengthening or weakening interactions based on its position.

Conclusions:

• The stability and electronic properties of adenine quartets are highly sensitive to substituent modifications.
• Remote substituents can influence the hydrogen-bonding capabilities of adenine.
• Understanding these structure-property relationships is crucial for designing novel adenine-based supramolecular systems.