Preparation and Characterization of Carbazole-Based Luminogen with Efficient Emission in Solid and Solution States

Area of Science:

• Organic Chemistry
• Materials Science
• Photophysics

Background:

• Organic luminescent materials with dual-state emission (DSE) are crucial for advanced applications.
• Developing novel DSE materials with high efficiency in both solution and solid states remains a key research area.

Purpose of the Study:

• To synthesize and characterize a new DSE luminogen based on carbazole.
• To investigate the photophysical properties, thermochromic, and mechanochromic behaviors of the novel material.
• To explore the potential application of the material in detecting hazardous substances.

Main Methods:

• Synthesis of 2-(4-(9H-carbazol-9-yl)phenyl)benzo[d]thiazole (CZ-BT).
• Photoluminescence spectroscopy to determine fluorescence quantum yields in solution and solid states.
• Thermogravimetric analysis and variable temperature spectroscopy for thermochromic studies.
• Grinding and heating experiments for mechanochromic property evaluation.
• Density Functional Theory (DFT) calculations for theoretical insights.

Main Results:

• CZ-BT demonstrated high fluorescence quantum yields: 70% (solution), 38% (amorphous solid), and 75% (crystalline solid).
• The material exhibited thermochromic properties in solution and mechanochromic properties in the solid state.
• Theoretical calculations revealed a small conformational difference between ground and excited states, low non-radiative transition probability, and high oscillator strength (1.0442).
• CZ-BT showed a low detection limit of 2.81 × 10⁻⁷ mol/L for picric acid.

Conclusions:

• CZ-BT is a novel organic luminogen with excellent dual-state emission properties.
• The observed properties can be attributed to its distorted molecular conformation and intramolecular hindrance.
• CZ-BT shows promise for applications in sensing hazardous substances like picric acid.