Conjugated polymers with large effective Stokes shift: benzobisdioxole-based poly(phenylene ethynylene)s

Area of Science:

• Organic Chemistry
• Polymer Science
• Materials Science

Background:

• Conjugated copolymers are crucial for organic electronics.
• Understanding electronic structure is key to designing new materials.
• Benzo[1,2-d:4,5-d']bis[1,3]dioxole (BDO) is a functional unit for tuning electronic properties.

Purpose of the Study:

• To synthesize and characterize phenyleneethynylene-based conjugated copolymers incorporating BDO units.
• To investigate the electronic and optical properties of these novel copolymers.
• To understand the relationship between molecular structure and photophysical behavior.

Main Methods:

• Synthesis of phenyleneethynylene-based conjugated copolymers.
• Spectroscopic analysis (UV-Vis absorption, fluorescence).
• Computational modeling (DFT) to predict electronic structure and properties.

Main Results:

• The BDO unit induces a localized HOMO and delocalized LUMO, resulting in intramolecular charge transfer.
• The polymers exhibit a distinct lowest optical absorption band with significant charge transfer character.
• Large Stokes shifts observed in monomers are largely retained in the polymers due to constrained dihedral angles.

Conclusions:

• The incorporation of BDO units offers a new strategy for designing conjugated copolymers with tailored electronic and optical properties.
• The observed electronic structure and photophysical behavior are consistent with computational predictions.
• These findings contribute to the development of advanced organic materials for optoelectronic applications.