N-Heteroaromatic Fused BODIPY Dimers: Ring-Size Effects from Five- to Six-Membered Rings

Area of Science:

• Organic Chemistry
• Materials Science
• Photophysics

Background:

• Boron-dipyrromethene (BODIPY) dyes are widely used in various applications due to their favorable photophysical properties.
• Functionalization of BODIPY units allows for fine-tuning of their electronic and optical characteristics.
• Fused heterocyclic systems offer unique structural motifs for modulating molecular properties.

Purpose of the Study:

• To synthesize novel BODIPY dimers incorporating five- and six-membered N-heterocycles.
• To investigate the impact of N-heterocycle size on the electronic delocalization and excited-state properties of BODIPY dimers.
• To explore structure-property relationships for developing advanced functional materials.

Main Methods:

• Synthesis of BODIPY dimers via nucleophilic aromatic substitution (SNAr) and C-H activation strategies.
• Characterization of the synthesized compounds using spectroscopic and electrochemical techniques.
• Computational modeling to understand electronic delocalization and charge-transfer characteristics.

Main Results:

• Successful synthesis of three BODIPY dimers fused with five- and six-membered N-heterocycles.
• The six-membered fused PP-di demonstrated panchromatic absorption, a reduced HOMO-LUMO gap, and enhanced intramolecular charge-transfer (ICT).
• The five-membered analogues, Cl-PL-di and PL-di, exhibited predominantly localized excited states.

Conclusions:

• N-heterocycle size is a critical factor in modulating the photophysical properties of BODIPY dimers.
• The PP-di derivative shows potential for applications requiring broad absorption and efficient charge separation.
• This study provides insights into the rational design of BODIPY-based materials with tailored electronic and optical properties.