Cationic and Betaine-Type Boronated Acridinium Dyes: Synthesis, Characterization, and Photocatalytic Activity

Area of Science:

• Organic Chemistry
• Photochemistry
• Materials Science

Background:

• Acridinium dyes are known for their unique photophysical properties.
• Boron-containing organic compounds offer tunable electronic and optical characteristics.
• Developing efficient photocatalysts for visible-light reactions is a key area of research.

Purpose of the Study:

• To synthesize novel isomeric boronated acridinium dyes.
• To investigate the impact of boron group position on photophysical properties.
• To explore the photocatalytic activity of these dyes in organic transformations.

Main Methods:

• Synthesis of boronated acridinium dyes via functionalized acridanone derivatives and lithiated phenylboronic azaesters.
• Spectroscopic analysis (UV-vis absorption, fluorescence) to characterize photophysical properties.
• Cyclic voltammetry to study electrochemical behavior.
• Theoretical calculations to elucidate excitation processes.
• Testing photocatalytic activity in visible-light-promoted addition reactions.

Main Results:

• A series of isomeric boronated acridinium dyes were successfully synthesized.
• The position of the boronic group significantly influences photophysical properties.
• Conversion to betaine trifluoroborato compounds altered UV-vis absorption and fluorescence.
• Electrochemical studies showed distinct redox potentials and stability for cationic and betaine forms.
• Theoretical calculations revealed different charge transfer mechanisms based on the boron substituent.
• The synthesized dyes demonstrated photocatalytic activity in addition reactions.

Conclusions:

• The position and nature of boron substituents critically affect the photophysical and electrochemical properties of acridinium dyes.
• Boronated acridinium dyes, including betaine forms, are promising candidates for photocatalysis.
• These compounds can be utilized in visible-light-promoted organic transformations, offering a sustainable synthetic approach.