A perylene bisimide derivative with pyrene and cholesterol as modifying structures: synthesis and fluorescence...

Area of Science:

• Organic Chemistry
• Photophysics
• Materials Science

Background:

• Cholesteryl residue incorporation enhances solubility of organic compounds.
• Perylene bisimide (PBI) and pyrene (Py) are known chromophores with distinct photophysical properties.

Purpose of the Study:

• To synthesize and characterize a novel perylene bisimide derivative (C-PBI-Py) with intra-molecular energy transfer capabilities.
• To investigate the photophysical properties, aggregation behavior, and energy transfer mechanisms of C-PBI-Py.
• To explore the potential of C-PBI-Py in developing new environment-sensitive fluorophores.

Main Methods:

• Synthesis of C-PBI-Py and reference compounds.
• UV-vis absorption and steady-state fluorescence spectroscopy.
• Cyclic voltammetry and theoretical calculations.
• Time-resolved and temperature-dependent emission spectroscopy.
• Concentration-dependent (1)H NMR spectroscopy.

Main Results:

• C-PBI-Py exhibits distinct PBI and Py chromophores with efficient intra-molecular energy transfer from Py to PBI.
• The PBI moiety forms aggregates, leading to H-type and J-type excimer emissions.
• Excimer formation occurs via Birks' or pre-formed schemes due to strong π-π stacking.
• Energy transfer proceeds via an electron exchange mechanism (Dexter scheme).

Conclusions:

• The designed C-PBI-Py derivative demonstrates efficient intra-molecular energy transfer and aggregation-induced excimer emission.
• Understanding these photophysical processes is crucial for designing novel solvatochromic and environment-sensitive fluorophores.
• The cholesteryl residue effectively enhances solubility in organic solvents.