Intermolecular chiral recognition probed by enantiodifferential excited-state quenching kinetics

Area of Science:

• Chemical Kinetics
• Photochemistry
• Supramolecular Chemistry

Background:

• Chirality plays a crucial role in molecular recognition and biological processes.
• Studying enantioselective interactions in solution is vital for understanding chemical and biological systems.
• Luminescent coordination complexes offer sensitive probes for molecular interactions.

Purpose of the Study:

• To investigate chirality-dependent excited-state quenching processes in aqueous solutions.
• To explore the kinetics of chiral discrimination between luminophores and quenchers.
• To understand how molecular structure influences enantioselective quenching.

Main Methods:

• Utilizing time-resolved chiroptical luminescence (TR-CL) spectroscopy.
• Employing racemic mixtures of chiral luminophores (Eu(dpa)3(3-) or Tb(dpa)3(3-)) and chiral quenchers (Cr/Rh-ATP complexes).
• Monitoring differential decay kinetics of excited-state enantiomers (lambda L* and delta L*).

Main Results:

• Demonstrated that chiral quenchers can differentiate between lambda and delta enantiomers of luminophores.
• Observed diverse enantiodifferential quenching kinetics across 21 luminophore-quencher systems.
• Showed that quenching preference is governed by quencher's electronic and stereochemical properties.

Conclusions:

• Chiral recognition and discrimination are highly sensitive to subtle changes in molecular structure.
• TR-CL is a powerful technique for probing enantioselective interactions in solution.
• Molecular design of quenchers can tune the degree and sense of chiral discrimination.