Ketoprofen Recognition and Sensing by Zn(II) Complexes with Fluorogenic Triamine Receptors

Area of Science:

• Coordination Chemistry
• Supramolecular Chemistry
• Fluorescent Sensors

Background:

• Fluorescent polyamine receptors often suffer from fluorescence quenching via photoinduced electron transfer (PET).
• Designing ligands that modulate PET is crucial for developing effective fluorescent sensors and drug delivery systems.

Purpose of the Study:

• To synthesize and characterize novel ligands (L1 and L2) incorporating triamine moieties and anthracene fluorophores.
• To investigate the coordination behavior of these ligands with Zn(II) ions.
• To explore the influence of Zn(II) binding and subsequent ketoprofen (KP) complexation on the fluorescence properties of the ligands.

Main Methods:

• Synthesis of diethylenetriamine (L1) and dipropylenetriamine (L2) based ligands.
• Formation and characterization of Zn(II) complexes.
• Spectroscopic studies (fluorescence) to analyze metal ion and drug binding.
• Computational modeling including ab initio calculations and molecular dynamics simulations.

Main Results:

• Stable 1:1 Zn(II) complexes with L1 and L2 were formed, with metal coordination by all ligand nitrogens.
• Zn(II) binding to L1 enhanced fluorescence by inhibiting PET; Zn(II) binding to L2 caused quenching due to cation π interactions.
• Ternary complexes with ketoprofen ([KPZnL]+ and [(KP)2ZnL]) were formed.
• Ketoprofen binding enhanced L2 fluorescence but slightly reduced L1 fluorescence, again attributed to cation π contacts.

Conclusions:

• Ligand structure dictates the photophysical response upon Zn(II) and ketoprofen binding.
• The interplay between PET inhibition and cation π interactions governs fluorescence modulation.
• These findings offer insights into the design of responsive fluorescent materials for sensing and potential therapeutic applications.