Structure-property relationships in quinazoline-based photoluminescent emitters

Area of Science:

• Materials Chemistry
• Computational Chemistry
• Photophysics

Background:

• Designing novel chromophores with predictable optical and photophysical properties remains a significant challenge.
• Quinazoline compounds are underexplored chromophores for materials chemistry, despite their potential for specific wavelength emission.

Purpose of the Study:

• To rationalize the optical and photophysical properties of six quinazoline compounds.
• To establish a predictive method for chromophore design by examining excited-state (anti)aromaticity.
• To explore structure-property relationships for developing new chromophores.

Main Methods:

• Examined S1 excited-state (anti)aromaticity using nuclear-independent chemical shift (NICS) indices.
• Investigated charge density accumulation and its effect on fluorescence yields.
• Correlated NICS indices with interatomic distance matrix differences between S1 and S0 states.
• Synthesized and studied three new quinazoline derivatives.

Main Results:

• Accumulation of charge density in S1 state π* levels diminishes fluorescence yields in solution without electron acceptors.
• Increased charge on the quinazoline core enhances antiaromaticity in the Franck-Condon geometry, promoting relaxation.
• NICS indices effectively predict the extent of core deformation during relaxation from Franck-Condon to S1 minimum.
• Established structure-property relationships for the studied quinazoline compounds.

Conclusions:

• The study demonstrates a method to predict and rationalize chromophore properties using NICS indices.
• Synergistic experimental and theoretical approaches are crucial for the rational design of novel chromophores.
• Findings facilitate the screening of promising quinazoline candidates for materials chemistry applications.