[QSAR and aromatic series: proposals for steric parameters]

Area of Science:

• Medicinal Chemistry
• Physical Organic Chemistry
• Quantitative Structure-Activity Relationships (QSAR)

Background:

• Steric parameters are crucial for understanding molecular interactions in chemical and biological systems.
• Existing steric parameters like molar refractivity (RM) and 1-octanol/water partition coefficient (Xv) have limitations in describing molecular shape.
• A need exists for a more precise steric descriptor for aromatic systems.

Purpose of the Study:

• To propose a novel steric parameter, sigma D, for characterizing aromatic molecules.
• To evaluate the efficacy of sigma D in comparison to established steric parameters.
• To determine the applicability of sigma D across diverse series of aromatic compounds.

Main Methods:

• Definition of sigma D as the perimeter of the molecule's efficacious section in the plane of the aromatic ring.
• Systematic comparison of sigma D with RM and 1Xv.
• Evaluation across six distinct series of aromatic molecules.

Main Results:

• The proposed sigma D parameter effectively quantifies steric properties of aromatic molecules.
• In most evaluated series, sigma D demonstrated superior performance compared to RM and 1Xv.
• The new parameter offers a potentially more accurate representation of molecular steric bulk.

Conclusions:

• Sigma D is a valuable new steric descriptor for aromatic systems.
• This parameter shows promise for improving QSAR models and understanding structure-property relationships.
• Further investigation into sigma D's applications in various chemical contexts is warranted.