BODIPY-bridged push-pull chromophores for nonlinear optical applications

Area of Science:

• Organic Chemistry
• Materials Science
• Photophysics

Background:

• Development of novel organic dyes with tailored electronic properties is crucial for advanced optical applications.
• Push-pull systems, characterized by electron-donating and electron-accepting moieties, are fundamental for nonlinear optical (NLO) materials.
• BODIPY dyes offer a robust and versatile scaffold for constructing functional chromophores.

Purpose of the Study:

• To synthesize and characterize a series of linear and dissymmetric BODIPY-bridged push-pull dyes.
• To investigate the electrochemical, linear, and nonlinear optical properties of these novel dyes.
• To explore the potential of these dyes for applications in nonlinear optics, particularly focusing on their hyperpolarizability and responsiveness to external stimuli.

Main Methods:

• Synthesis of BODIPY-bridged push-pull dyes incorporating anisole and dialkylanilino donor groups and a 1,1,4,4-tetracyanobuta-1,3-diene (TCBD) acceptor group.
• Full characterization of synthesized dyes using spectroscopic and analytical techniques.
• Evaluation of electrochemical properties through cyclic voltammetry.
• Measurement of linear and nonlinear optical properties, including solvatochromism and hyperpolarizability (μβ) using electric-field-induced second-harmonic generation (EFISHG).

Main Results:

• Successful synthesis of novel BODIPY-bridged push-pull dyes with tunable electronic structures.
• Dialkylamino-substituted dyes exhibited strong solvatochromic behavior and significant spectral changes upon protonation.
• The TCBD-BODIPY dyes displayed diverse photochemistry and electrochemistry, including multiple reversible reduction waves for the TCBD moiety.
• Two TCBD-BODIPY dyes achieved exceptionally high hyperpolarizability values (μβ) of 2050 × 10⁻⁴⁸ and 5900 × 10⁻⁴⁸ esu.
• One dye demonstrated a high nonlinear optical contrast upon protonation-deprotonation of the donor group.

Conclusions:

• The synthesized TCBD-BODIPY dyes represent a promising class of materials for nonlinear optics.
• The observed tunability through structural modification and external stimuli (protonation) highlights their potential for smart optical devices.
• The high hyperpolarizability values indicate their suitability for applications requiring strong NLO responses.