Chalcogen Atom Size: A Key Parameter in Modulating Carbonyl Compound Properties.

Area of Science:

• Organic Chemistry
• Computational Chemistry
• Materials Science

Background:

• Carbonyl groups (C=O) are fundamental in organic chemistry.
• Tuning electronic properties of conjugated systems is crucial for advanced applications.
• Electronegativity and energy gaps influence molecular behavior and reactivity.

Purpose of the Study:

• To investigate the effect of replacing carbonyl oxygen with sulfur or selenium on molecular properties.
• To explore the underlying reasons for observed changes in electronegativity and energy gaps.
• To highlight potential applications of this chemical modification.

Main Methods:

• Quantum-chemical calculations were employed to analyze molecular electronic structures.
• Comparative studies of C=O, C=S, and C=Se containing π-conjugated systems.
• Analysis focused on electronegativity, HOMO-LUMO energy gaps, and steric effects.

Main Results:

• Substitution of oxygen with sulfur or selenium in C=X groups unexpectedly enhanced electronegativity.
• The molecular π HOMO-LUMO energy gap was reduced by this substitution.
• Steric size of the chalcogen atom (X) was identified as the primary cause for these counterintuitive effects.

Conclusions:

• Varying the chalcogen atom in C=X bonds provides a novel method for tuning electronic properties of conjugated molecules.
• This chalcogen-based tuning offers significant potential in organocatalysis, supramolecular chemistry, and photo(electro)chemistry.
• The findings enable rational design of new functional organic materials.