A Tethered Tolane: Twisting the Excited State

Area of Science:

• Organic Chemistry
• Photochemistry
• Materials Science

Background:

• Bridged tolanes are complex organic molecules with unique structural and electronic properties.
• Understanding the photophysical behavior of twisted aromatic systems is crucial for developing new optical materials.

Purpose of the Study:

• To synthesize a novel doubly bridged tolane.
• To investigate the structural, optical, and photophysical properties of the synthesized molecule.
• To explore the emission characteristics in different states and temperatures.

Main Methods:

• A five-step synthesis starting from 2-amino-meta-xylene.
• Utilized Sandmeyer reaction, radical bromination, and Stille-type coupling.
• Employed double ring closing for target molecule formation.
• Characterized using optical spectroscopy and quantum chemical calculations.

Main Results:

• Successfully synthesized a crystalline doubly bridged tolane.
• Observed significant twisting of phenyl rings in both solution and solid states.
• Demonstrated emission from the twisted state in solution and solid states.
• Detected strong phosphorescence at cryogenic temperatures.

Conclusions:

• The doubly bridged tolane maintains a twisted conformation in both ground and excited states.
• The twisted structure dictates the molecule's unique photophysical behavior, including emission properties.
• The observed phosphorescence at low temperatures suggests potential applications in optoelectronics.