Two phases of trans-stilbene in a polystyrene matrix

Area of Science:

• Photophysics and molecular spectroscopy
• Solid-state chemistry
• Materials science

Background:

• The spectral properties of solid-state organic molecules, like trans-stilbene, are complex and influenced by conformation and environment.
• Understanding these properties is crucial for applications in materials science and optoelectronics.
• Variability in spectral characteristics under different conditions remains a challenge.

Purpose of the Study:

• To investigate the photophysical properties of trans-stilbene in a solid polystyrene matrix.
• To elucidate the influence of concentration on spectral behavior and phase characteristics.
• To explore the structural basis for observed spectroscopic phenomena.

Main Methods:

• Absorption and time-resolved fluorescence spectroscopy were employed.
• Ab initio calculations and molecular dynamics simulations were utilized.
• Analysis of spectral data in relation to sample concentration and phase behavior.

Main Results:

• Concentration-dependent quenching was observed at low trans-stilbene concentrations.
• At high concentrations, absorption and fluorescence spectra showed distinct phase separation.
• Absorption spectra correlated with single-molecule properties, while fluorescence spectra reflected micro-crystalline phases.
• Computational analyses revealed permanent twisting of the stilbene structure upon crystallization.

Conclusions:

• The study demonstrates spectroscopic phase separation in trans-stilbene/polystyrene solid solutions.
• Molecular twisting in the crystalline phase is a key factor driving this separation.
• These findings provide insights into controlling spectral properties of organic molecules in solid matrices.