A Simple Central Seven-Membered BOPYIN: Synthesis, Structural, Spectroscopic Properties, and Cellular Imaging...

Area of Science:

• Organic Chemistry
• Materials Science
• Photophysics

Background:

• Borondifluoride complexes are valuable in various applications.
• Organoboron compounds with indole moieties are less explored.
• Understanding the structure-property relationships of novel boron heterocycles is crucial.

Purpose of the Study:

• To develop a facile synthetic route for seven-membered borondifluoride-3,3-dimethyl-2-[2-(2-pyrrolyl)ethenyl] indole (BOPYIN) ligands.
• To investigate the structural, photophysical, and electronic properties of the synthesized BOPYIN derivatives.
• To evaluate the potential of BOPYINs as biocompatible fluorophores for cell bioimaging.

Main Methods:

• Two-step, one-flask synthesis of BOPYIN ligands.
• Modification of electronic structure via indole substituents.
• X-ray crystallography for structural analysis.
• Spectroscopic measurements (absorption, emission) and TDDFT calculations.
• Lippert-Mataga analysis for dipole moment determination.

Main Results:

• Successful synthesis of novel BOPYIN ligands with tunable electronic structures.
• X-ray analysis revealed unique conformations of seven-membered BF2 complexes.
• BOPYIN derivatives demonstrated high fluorescence quantum yields, large Stokes shifts, and good molar absorptivity.
• Deviations from Kasha's rule observed in absorption and emission spectra.
• Demonstrated biocompatibility of BOPYINs as fluorophores in cell bioimaging.

Conclusions:

• A straightforward synthetic strategy for BOPYIN ligands has been established.
• The synthesized BOPYINs possess promising photophysical characteristics for fluorescent applications.
• The structural insights support Baeyer strain theory in organoboron complexes.
• BOPYINs are effective and biocompatible fluorophores for cellular imaging.